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Journal Cover Pest Management Science
  [SJR: 1.258]   [H-I: 86]   [4 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1526-498X - ISSN (Online) 1526-4998
   Published by John Wiley and Sons Homepage  [1592 journals]
  • Effects of seed mixture sowing with resistant and susceptible rice on
           population dynamics of target planthoppers and non-target stemborers and
    • Authors: Zhuo Li; Gui-jun Wan, Long Wang, Megha N. Parajulee, Zi-hua Zhao, Fa-jun Chen
      Abstract: BACKGROUNDThe widespread planting of insect-resistant crops has caused a dramatic shift in agricultural landscapes, thus raising concerns about the potential impact on both target and non-target pests worldwide. In this study, we examined the potential effects of six seed-mixture ratios of insect-resistant dominance (100%-R100, 95%-S05R95, 90%-S10R90, 80%-S20R80, 60%-S40R60, and 0%-S100) on target and non-target pests in a 2-year field trial in southern China.RESULTSThe occurrence of target pests, Nilaparvata lugens and Sogatella furcifera, decreased with the increased ratio of resistant rice, and the mixture ratios with ≥90% resistant rice significantly increased the pest suppression efficiency, with lowest occurrences of non-target pests, Sesamia inferens, Chilo suppressalis and Cnaphalocrocis medinalis, in S100 and S10R90 seed-mixture ratios. Furthermore, there were no significant differences in the 1000-grain dry weight and grain yield between R100 versus treatments with ≥80% resistant seed mixture (S20R80, S10R90 and S05R95).CONCLUSIONS10R90 resulted in good yield and provided the most effective control of both target and non-target pests, with potential to significantly reduce the application of chemical pesticides for integrated pest management in paddy fields. It is further presumed that the strategy of seed mixture with resistant and susceptible rice would be advantageous for rice yield stability.
      PubDate: 2018-01-13T02:40:20.785756-05:
      DOI: 10.1002/ps.4860
  • Testing a chemical series inspired by plant stress oxylipin signaling
           agents for herbicide safening activity
    • Authors: Melissa Brazier-Hicks; Kathryn M. Knight, Jonathan D. Sellars, Patrick G. Steel, Robert Edwards
      Abstract: BACKGROUNDHerbicide safening in cereals is linked to a rapid xenobiotic response (XR), involving the induction of glutathione transferases (GSTs). The XR is also invoked by oxidized fatty acids (oxylipins) released during plant stress, suggesting a link between these signaling agents and safening. To examine this relationship, a series of compounds modelled on the oxylipins 12-oxophytodienoic acid and phytoprostane 1, varying in lipophilicity and electrophilicity were synthesized. Compounds were then tested for their ability to invoke the XR in Arabidopsis and protect rice seedlings exposed to the herbicide pretilachlor, as compared with the safener fenclorim.RESULTSOf the 21 compounds tested, three invoked the rapid GST induction associated with fenclorim. All compounds possessed two electrophilic carbon centres and a lipophilic group characteristic of both oxylipins and fenclorim. Minor effects observed in protecting rice seedlings from herbicide damage positively correlated with the XR, but did not provide functional safening.CONCLUSIONThe design of safeners based on the characteristics of oxylipins proved successful in deriving compounds that invoke a rapid XR in Arabidopsis but not in providing classical safening in a cereal. The results further support a link between safener and oxylipin signaling, but also highlight species-dependent differences in the responses to these compounds.
      PubDate: 2018-01-13T02:30:20.348617-05:
      DOI: 10.1002/ps.4859
  • The Mechanism of Diflufenican Resistance and its Inheritance in Oriental
           Mustard (Sisymbrium orientale L.) from Australia
    • Authors: Hue Thi Dang; Jenna Moira Malone, Peter Boutsalis, Gurjeet Gill, Christopher Preston
      Abstract: BACKGROUNDAn oriental mustard population (P3) collected near Quambatook, Victoria was identified resistant to diflufenican by screening with the field rate (200 g a.i. ha-1) of the herbicide. The mechanism (s) of diflufenican resistance and its inheritance in this population was therefore investigated.RESULTSDose-response experiment confirmed population P3 was 140-fold more resistant to diflufenican as determined by the comparison of LD50 values with the susceptible populations. The phytoene desaturase gene was sequenced from 5 individuals each of the S1 (S) and P3 (R) populations with a substitution of valine for leucine at position 526 (Leu-526-Val) detected in the all 5 individuals of P3, but not in the S1 population. Inheritance studies showed that diflufenican-resistance is encoded on the nuclear genome and is dominant, as the response to diflufenican at 200 g a.i. ha-1 of F1 families were equivalent to the resistant biotype. The segregation of F2 phenotypes fitted a 3:1 inheritance model. Segregation of 42 F2 individuals by genotype sequencing fitted a 1:2:1 (ss:Rs:RR) ratio.CONCLUSIONResistance to diflufenican in oriental mustard is conferred by Leu-526-Val mutation in the PDS gene. Inheritance of resistance is managed by a single gene with high levels of dominance.
      PubDate: 2018-01-13T02:15:21.222633-05:
      DOI: 10.1002/ps.4858
  • Dissipation, pre-harvest interval estimation, and dietary risk assessment
           of carbosulfan, dimethoate, and their relevant metabolites in greenhouse
           cucumber (Cucumis sativus L.)
    • Authors: Yue Geng; Linjie Jiang, Yanwei Zhang, Zeying He, Lu Wang, Yi Peng, Yuehua Wang, Xiaowei Liu, Yaping Xu
      Abstract: BACKGROUNDThe dissipation behavior, pre-harvest interval estimation, and dietary risk assessment of carbosulfan, dimethoate, and their relevant metabolites were investigated in greenhouse cucumber in Tianjin, northern China, to ensure raw consumption safety.RESULTSCarbosulfan was metabolized to carbofuran, dibutylamine, 3-hydroxycarbofuran, 3-ketocarbofuran as well as dimethoate was degraded to omethoate in cucumber fruits and leaves. The dissipation of carbosulfan, carbofuran, 3-hydroxycarbofuran, and dimethoate fitted first-order kinetics well with R2 ranged from 0.912 to 0.992, their half-lives were 2.6, 2.7, 2.4, 5.2 days in cucumber fruits and 2.8, 3.0, 4.6, 2.5 days in leaves. The estimated daily intakes of the active ingredients and their relevant metabolites utilized 0.1-4% of the corresponding acceptable daily intake. The acute oral exposure of carbofuran (a metabolite of carbosulfan) utilized 367% of acute reference dose (ARfD) for 1-6 years Chinese children and 227% for general Chinese population.CONCLUSIONThe minimum pre-harvest interval of 12 days for carbosulfan is proposed to ensure safe consumption of cucumber. The slow dissipation rate of omethoate in cucumber reveals longer pre-harvest interval (≥ 27 days) is necessary to protect dietary risk when dimethoate is applied to cucumber.
      PubDate: 2018-01-12T02:50:33.005995-05:
      DOI: 10.1002/ps.4857
  • Coexistence of Bt-transgenic and conventional rice affects insect
           abundance and plant fitness in fields
    • Authors: Yuyong Liang; Fang Liu, Junsheng Li, Zhengxin Cheng, Hongfan Chen, Xuming Wang, Nengwen Xiao, Yongbo Liu
      Abstract: BACKGROUNDAs genetically modified (GM) crops have been cultivated worldwide, concerns emerge over ecological consequences because of the coexistence of transgenic and non-transgenic crops in fields. We first conducted field experiments using insect-resistant Bt-transgenic rice expressing Bacillus thuringiensis and its counterpart conventional rice (Oryza sativa L.) with or without insecticide spraying in 2013 and 2014. In 2015 and 2016, Bt-transgenic and conventional rice were employed in the pure and mixed cages, with an infestation of target insect (Chilo suppressalis) and insecticide spraying as the control treatment to prevent target insects.RESULTSBt-transgenic rice decreased the abundance of target insects but did not affect the non-target insects and predators in fields. Compared to conventional rice, Bt-transgenic rice showed more empty seeds but comparable seed production in cages. Infestation of target-insects significantly decreased the plant fitness of conventional rice in pure cages, but did not affect them when conventional rice coexisted with Bt rice. In mixed cages, the presence of Bt-transgenic rice decreased the abundance of target insects and the percentage of dead sheath in conventional rice.CONCLUSIONThe presence of Bt-transgenic rice benefits the growth and reproduction of non-transgenic rice in fields because of a decreased abundance of target insects.
      PubDate: 2018-01-09T21:46:43.176559-05:
      DOI: 10.1002/ps.4856
  • One-pot synthesis of anilides, herbicidal activity and molecular docking
    • Authors: Suélen K Sartori; Elson S Alvarenga, Cristiane A Franco, Danielle S Ramos, Denilson F Oliveira
      Abstract: BACKGROUNDConsidering the demand for more efficient herbicides, the present work aimed at synthesizing anilides via simple methods, and evaluate their herbicidal activities through seed germination assays. In silico studies were carried out to identify the enzymatic target sitein the plants for the most active anilides.RESULTSA total of eighteen anilides were prepared via one-pot reaction in yields which varied from 36 to 98% through reactions of anilines with sorbic chloride and hexanoic anhydride. According to seed germination assays against three dicotyledonous and one monocotyledonous plant species, the most active anilides presented root and shoot growth inhibition superior to Dual (S-metolachlor). In silico studies showed histone deacetylase as the probable enzymatic target site in plants for these substances. The affinities of the most active anilides for the binding sites of this enzyme were equal to or higher than those calculated for its inhibitors.CONCLUSIONAnilides 4d, 4e, 4g, and 4h are promising candidates for the development of novel herbicides. According to in silico studies they inhibit histone deacetylase in plants, which can be exploited for the development of new weed control methods.
      PubDate: 2018-01-09T21:31:47.794091-05:
      DOI: 10.1002/ps.4855
  • Antiphytoviral toxins of Actinidia chinensis root bark (ACRB) extract:
           laboratory and semi-field trials
    • Authors: XiuYun Zhang; Yu Zhou, ZhiPing Wei, Jing Shen, LongKun Wang, ZhiQing Ma, Xing Zhang
      Abstract: BACKGROUNDActinidia chinensis Planch, distributed only in China, has been used to treat hepatitis and cancer. The objective of the present work was to illustrate the antiviral active ingredient of A. chinensis root bark (ACRB).RESULTSBioassay-guided isolation of the most active fraction, EtOAc extract, led to seven compounds, (+)-catechins-7-phytol (1), 5-methoxy-coumarin-7-β-D-glycosidase (2), (+)-catechins (3), fupenzic acid (4), spathodic acid-28-O-β-D-glucopyranoside (5), 3-oxo-9 (11),12 -diene-30-oic acid (6), and 3-β-(2-carboxy benzoyloxy) oleanolic acid (7). Of them, 5-methoxy-coumarin-7-β-D-glycosidase (2) possessed the highest anti-viral activity, followed by spathodic acid-28-O-β-D-glucopyranoside (5). Thus, compounds (2) and (5) were the main active constituents, showing the potential for their further development as biological antiviral agents.CONCLUSIONThe results suggested that ACRB possess great potential value for developing an antiviral agent to control phytoviral diseases.
      PubDate: 2018-01-09T21:09:49.272168-05:
      DOI: 10.1002/ps.4854
  • Evidence for activation of nitenpyram by a mitochondrial cytochrome P450
           in Drosophila melanogaster
    • Authors: Thomas W.R. Harrop; Shane Denecke, Ying Ting Yang, Janice Chan, Phillip J. Daborn, Trent Perry, Philip Batterham
      Abstract: BACKGROUNDNitenpyram is a member of the economically important neonicotinoid class of insecticides. The in vivo metabolism of nitenpyram is not well characterised, but cytochrome P450 activity is the major mechanism of resistance to neonicotinoids identified in insect pests, and P450s metabolise other neonicotinoids including imidacloprid.RESULTSHere, we used the GAL4/UAS system to direct RNAi against the cytochrome P450 redox partners to interrupt P450 functions in specific tissues in Drosophila melanogaster. RNAi of the mitochondrial redox partner dare in the digestive tissues reduced nitenpyram mortality, suggesting an activation step in the metabolism of nitenpyram carried out by a mitochondrial P450. RNAi of the mitochondrial P450 Cyp12a5, which is expressed in the digestive tissues, resulted in the same phenotype, and transgenic overexpression of Cyp12a5 increased nitenpyram sensitivity.CONCLUSIONThese results suggest that in vivo metabolism of nitenpyram by the mitochondrial P450, CYP12A5, results in the formation of a product with higher toxicity than the parent compound.
      PubDate: 2018-01-09T11:08:59.568699-05:
      DOI: 10.1002/ps.4852
  • Antifeedant effect of polygodial and drimenol derivatives against
           Spodoptera frugiperda and Epilachna paenulata and Quantitative Structure
           -Activity analysis
    • Authors: Iván J. Montenegro; Soledad del Corral, Georgina N. Diaz Napal, María C. Carpinella, Marco Mellado, Alejandro M. Madrid, Joan Villena, Sara M. Palacios, Mauricio A. Cuellar
      Abstract: BACKGROUNDThe antifeedant activity of 18 sesquiterpenoids of the drimane family (polygodial, drimenol and derivatives) was investigated. The results of this study against two insect species, Spodoptera frugiperda and Epilachna paenulata showed that polygodial, drimanic and nordrimanic derivatives exert antifeedant effects in these pests of agronomic interest indicating that they have potential as a biopesticide agent.RESULTSAmong the 18 compounds tested, the epoxynordrimane compound (11) and isonordrimenone (4) showed itself the highest activity (EC50 = 23.28 and 25.63 nmol/cm2, respectively against S. frugiperda; and 50.50 and 59.00 nmol/cm2, respectively against E. paenulata).CONCLUSIONThe results of the present study suggest that drimanic compounds against could arise as new agents for the treatment of S. frugiperda and E. paenulata. A QSAR analysis of the whole series, supported by electronic studies suggest drimanic compounds have structural features necessary for increasing the antifeedant activity namely a C-9 carbonyl group and epoxide at C-8 and C-9 group.
      PubDate: 2018-01-08T11:05:23.078269-05:
      DOI: 10.1002/ps.4853
  • Pesticides & passive dispersal: acaricide- and starvation-induced take-off
           of the predatory mite Neoseiulus baraki
    • Authors: Vaneska Barbosa Monteiro; Vanessa Farias Silva, Debora Barbosa Lima, Raul Narciso Carvalho Guedes, Manoel Guedes Correa Gondim
      Abstract: BACKGROUNDAn understanding of the causes and consequences of dispersal is vital for managing populations. Environmental contaminants, such as pesticides, provide potential environmental context-dependent stimuli for dispersal of targeted and non-targeted species, which may occur not only for active but also for passive dispersal, although such a possibility is frequently neglected. Here, we assessed the potential of food deprivation and acaricides to interfere with the take-off for passive (wind) dispersal of the predatory mite Neoseiulus baraki.RESULTSWind tunnel bioassays indicated that starvation favoured the take-off for wind dispersal by the mite predator, which also varied with wind velocity, and dispersal increased at higher velocities within the 1–7 m/s range tested. For the acaricides tested, particularly the biopesticide azadirachtin but also abamectin and fenpyroximate, predator take-off for dispersal increased, which further increased with wind velocity up to 7 m/s. Such responses were associated with changes in the predator behavioural preparation for wind-mediated passive dispersal, with greater incidence of the standing posture that permitted take-off.CONCLUSIONSThe take-off for passive dispersal by N. baraki increased with food deprivation and exposure to the residues of agriculture acaricides. Azadirachtin exposure resulted in a particularly strong response, although abamectin and fenpyroximate also stimulated dispersal.
      PubDate: 2018-01-08T10:45:21.836676-05:
      DOI: 10.1002/ps.4851
  • Cover Image, Volume 74, Issue 2
    • Authors: Chenxi Wu; Adam S Davis, Patrick J Tranel
      Abstract: The cover image, by Chenxi Wu et al., is based on the Research Article Limited fitness costs of herbicide-resistance traits in Amaranthus tuberculatus facilitate resistance evolution,
      DOI : 10.1002/ps.4706. Photo Credit: Chenxi Wu.The cover image, by Chenxi Wu et al., is based on the Research Article Limited fitness costs of herbicide-resistance traits in Amaranthus tuberculatus facilitate resistance evolution,
      DOI : 10.1002/ps.4706. Photo Credit: Chenxi Wu.
      PubDate: 2018-01-05T03:27:31.89489-05:0
  • QSAR analysis of plant-derived compounds with larvicidal activity against
           Zika Aedes aegypti (Diptera: Culicidae) vector using freely available
    • Authors: Laura M. Saavedra; Gustavo P. Romanelli, Pablo R. Duchowicz
      Abstract: BACKGROUNDWe develop a QSAR model for predicting the larvicidal activity of 60 plant-derived molecules against Aedes aegypti L. (Diptera: Culicidae), vector of several diseases such as, dengue, yellow fever, chikungunya and Zika virus. The balanced subsets method (BSM) based on k-means cluster analysis (k-MCA) is employed to split the data set. The replacement method (RM) variable subset selection technique coupled with multivariable linear regression (MLR) proves to be successful for exploring 18,326 molecular descriptors and fingerprints calculated with PaDEL, Mold2 and EPI Suite open-source software.RESULTSA robust QSAR model (Rtrain2=0.84, Strain = 0.20 and Rtest2=0.92, Stest = 0.23) involving five non-conformational descriptors is established. The model is validated and tested through the use of an external test set of compounds, the leave-one-out (LOO) and leave-more-out (LMO) cross-validation methods, the Y-randomization and applicability domain (AD) analysis.CONCLUSIONThe QSAR model surpasses previously published ones based on geometrical descriptors; thereby representing a suitable tool for predicting larvicidal activity against A. aegypti vector using a conformation-independent approach.
      PubDate: 2018-01-04T07:05:26.635514-05:
      DOI: 10.1002/ps.4850
  • Semiochemicals to enhance herbivory by Diorhabda carinulata aggregations
           in saltcedar (Tamarix spp.) infestations
    • Authors: Alexander M. Gaffke; Sharlene E. Sing, Tom L. Dudley, Daniel W. Bean, Justin A. Russak, Agenor Mafra-Neto, Paul A. Grieco, Robert K. D. Peterson, David K. Weaver
      Abstract: BACKGROUNDSemiochemicals for monitoring, attracting or repelling pest and beneficial organisms are increasingly deployed in agricultural and forest systems for pest management activities. However, the use of aggregation pheromones and host plant attractants for the express purpose of increasing the efficacy of classical biological control agents of weeds has not been widely reported. Therefore, we conducted field-based assays to determine if a specialized wax based matrix impregnated with an aggregation pheromone of the northern tamarisk beetle Diorhabda carinulata (Desbrochers) or host plant volatiles could increase the efficacy of D. carinulata.RESULTSThe aggregation pheromone and host plant volatiles were formulated for field application using a wax based matrix. Reported release rates suggest this matrix is a viable formulation for enhancing D. carinulata aggregations under field conditions. Pheromone-treated saltcedar plants (Tamarix spp.) not only had higher densities of adult and larval D. carinulata, but also sustained greater levels of foliar damage than control plants. Increased damage from the focused feeding of D. carinulata caused an increase in foliar dieback and decrease in live canopy volume of semiochemical-treated plants.CONCLUSIONField deployment of these semiochemical formulations could be useful in directing populations of D. carinulata for increased impact on Tamarix spp.
      PubDate: 2018-01-03T11:11:29.06911-05:0
      DOI: 10.1002/ps.4848
  • AHAS Trp-574-Leu substitution in Raphanus sativus L.: screening, enzyme
           activity and fitness cost
    • Authors: Roman B Vercellino; Claudio E Pandolfo, Gabriela Breccia, Miguel Cantamutto, Alejandro Presotto
      Abstract: BACKGROUNDFeral radish (Raphanus sativus L.) is a problematic weed that has become resistant to AHAS (acetohydroxyacid synthase) inhibitor herbicides due to the Trp-574-Leu mutation. AHAS gene mutation that causes herbicide resistance may present negative pleiotropic effects on plant fitness. This study reports the effects of the Trp-574-Leu mutation on AHAS activity and reproductive traits of R. sativus.RESULTSEight out of 17 feral radish accessions presented resistant individuals to metsulfuron-methyl from 0.5 to up to more than 90.0 % and all the resistant individuals analyzed showed the Trp-574-Leu mutation. Without herbicide selection, the AHAS activity of a susceptible accession was 3.2-fold higher than the resistant one. The resistant accession was> 9000-fold more resistant to metsulfuron-methyl and imazethapyr than the susceptible one. Under low intraspecific competition during two growing seasons, the AHAS resistant feral radish accessions showed 22 – 38 and 21 – 47 % lower seed number and yield per plant than the susceptible ones.CONCLUSIONThis is the first report of fitness cost associated with the AHAS Trp-574-Leu mutation in R. sativus populations. This fitness cost could reduce the frequency of the resistant allele without the herbicide selection.
      PubDate: 2018-01-03T07:50:26.41774-05:0
      DOI: 10.1002/ps.4849
  • Binding targets of termiticidal lectins from the bark and leaf of
           Myracrodruon urundeuva in the gut of Nasutitermes corniger workers
    • Authors: Thâmarah A. Lima; Leonardo P. Dornelles, Ana Patrícia S. Oliveira, Caio C.S. Guedes, Sueden O. Souza, Roberto A. Sá, Russolina B. Zingali, Thiago H. Napoleão, Patrícia M.G. Paiva
      Abstract: BACKGROUNDLectins, carbohydrate-binding proteins, from the bark (MuBL) and leaf (MuLL) of Myracrodruon urundeuva are termiticidal agents against Nasutitermes corniger workers, and have been shown to induce oxidative stress and cell death in the midgut of these insects. In this study, we investigated the binding targets of MuBL and MuLL in the gut of N. corniger workers by determining the effects of these lectins on the activity of digestive enzymes. In addition, we used mass spectrometry to identify peptides from gut proteins that adsorbed to MuBL-Sepharose and MuLL-Sepharose columns.RESULTSExoglucanase activity was neutralized in the presence of MuBL and stimulated by MuLL. α-L-Arabinofuranosidase activity was not affected by MuBL, but was inhibited by MuLL. Both lectins stimulated α-amylase activity and inhibited protease and trypsin-like activities. Peptides with homology to apolipophorin, trypsin-like enzyme, and ABC transporter substrate-binding protein were detected from proteins that adsorbed to MuBL-Sepharose, while peptides from proteins that bound to MuLL-Sepharose shared homology with apolipophorin.CONCLUSIONThis study revealed that digestive enzymes and transport proteins found in worker guts can be recognized by MuBL and MuLL. Thus, the mechanism of their termiticidal activity may involve changes in the digestion and absorption of nutrients.
      PubDate: 2018-01-03T06:30:22.583274-05:
      DOI: 10.1002/ps.4847
  • Remarkably efficient production of a highly insecticidal Chrysodeixis
           chalcites nucleopolyhedrovirus (ChchNPV) isolate in its homologous host
    • Authors: A Bernal; O Simón, T Williams, D Muñoz, P Caballero
      Abstract: BACKGROUNDA Chrysodeixis chalcites nucleopolyhedrovirus from the Canary Islands (ChchNPV-TF1) has proved to be effective for control of this pest on banana crops. Commercialization of this virus as a bioinsecticide requires an efficient production system.RESULTSThe most suitable larval instar for virus production was the sixth instar (L6), which produced 1.80x1011 occlusion bodies (OBs)/larva and showed a lower prevalence of cannibalism (5.4%) than fourth (L4) or fifth (L5) instars. Inoculation of L6 at 24 h post-molting produced six times more OBs (5.72x1011 OBs/larva) than recently molted L6 larvae (1.00x1011 OBs/larva). No significant differences were recorded in mean time to death (165-175 h) or OB production per larva (3.75x1011 to 5.97x1011 OBs) or per mg of larval weight (1.30x1011 to 2.11x109 OBs), in larvae inoculated with a range of inoculum concentrations (LC50 - LC90). Groups of infected L6 larvae reared at a density of 150 larvae/container produced a greater total number of OBs (8.07x1013 OBs/container), than lower densities (25, 50 and 100), and a similar number to containers with 200 inoculated larvae (8.43x1013 OBs/container).CONCLUSIONThe processes described here allow efficient production of sufficient OBs to treat ~40 ha of banana crops using the insects from a single container.
      PubDate: 2018-01-03T06:20:29.796566-05:
      DOI: 10.1002/ps.4846
  • Issue Information
    • Pages: 257 - 262
      PubDate: 2018-01-05T03:27:33.913864-05:
      DOI: 10.1002/ps.4681
  • Obituary: Professor Toshio Fujita
    • Authors: Yoshiaki Nakagawa; Guy Smagghe
      Pages: 263 - 263
      PubDate: 2018-01-05T03:27:36.949362-05:
      DOI: 10.1002/ps.4769
  • Reduced translocation in 2,4-D resistant oriental mustard populations
           (sisymbrium orientale L.) from Australia
    • Authors: Hue Thi Dang; Jenna M. Malone, Peter Boutsalis, Mahima Krishnan, Gurjeet Gill, Christopher Preston
      Abstract: BACKGROUNDTwo oriental mustard populations (P2 and P13) collected from Port Broughton, South Australia were identified as resistant to 2,4-D. The level of resistance, mechanism and the mode of inheritance for 2,4-D resistance in these populations were investigated.RESULTSPopulations P2 and P13 were confirmed to be resistant to 2,4-D at the field rate (600 g a.e. ha-1). The P2 and P13 were 81 and 67-fold more resistant compared to the susceptible populations (S1 and S2) at the LD50 level, respectively. No predicted amino acid modification was detected in sequences of potential target-site genes (ABP, TIR1 and AFB5). The resistant populations had reduced 2,4-D translocation compared to the susceptible populations, with 77% of [14C]2,4-D retained in the treated leaf vs 32% at 72 HAT. Resistance to 2,4-D is encoded on the nuclear genome and is dominant, as the response to 2,4-D of all F2 individuals were similar to the resistant biotypes. The segregation of F2 phenotypes fitted a 3:1 (R:S) inheritance model.CONCLUSIONResistance to 2,4-D in oriental mustard is likely due to reduced translocation of 2,4-D out of the treated leaf. Inheritance of 2,4-D resistance is conferred by a single gene with a high level of dominance.
      PubDate: 2017-12-29T09:45:23.141575-05:
      DOI: 10.1002/ps.4845
  • Thiocarbamate fungicides - Reliable tools in resistance management and
           future outlook
    • Authors: Tarlochan S Thind; Derek W Hollomon
      Abstract: Amongst contact fungicides, dithiocarbamates have remained successful fungicides and are used worldwide. These organic sulphur fungicides viz. mancozeb, maneb, zineb, ziram, thiram, metiram and propineb have helped growers manage several economically important plant diseases. Their multi-site mode of action and broad-spectrum disease control make them some of the most common mixture partners with a number of single-site fungicides as part of resistance management strategies. Indeed, it was the part played by ethylene-bis-dithiocarbamates such as mancozeb in delaying the evolution of phenylamide resistance in several oomycete phytopathogens that laid the groundwork for mixture strategies to become a cornerstone of anti-resistance management in plant disease control. Dithiocarbamates, however, do not have systemic action and are only surface protectants, and have to be applied prior to pathogen infection. Dithiocarbamates will likely continue play a key role as reliable resistance management tools to prolong the efficacy of single-site fungicides. The primary metabolite ethylene thiourea produced by some of these fungicides is considered to be reproductive and endocrine disrupter in animals. Therefore, dithiocarbamates need to be used at reduced rates or in slow release formulations.
      PubDate: 2017-12-29T09:25:26.50228-05:0
      DOI: 10.1002/ps.4844
  • Impact of sensor-controlled variable-rate fungicide application on yield,
           senescence and disease occurrence in winter wheat fields
    • Authors: Maria Tackenberg; Christa Volkmar, Michael Schirrmann, Antje Giebel, Karl-Heinz Dammer
      Abstract: BACKGROUNDField experiments related to target-oriented variable-rate fungicide spraying were performed in 2015 and 2016. The spray volume was adapted in real time to the local green coverage level of winter wheat (Triticum aestivum L.), which was detected by a camera sensor.RESULTSDepending on the growth heterogeneity in the three strip trials in 2015, the fungicide savings in the sensor sprayed strip compared to the adjacent uniformly sprayed strip were 44 %, 45 % and 1 %. In the field trial 2016, the saving was 12 %. There was no higher senescence or disease occurrence and no yield losses in the camera-controlled variable-rate sprayed strips compared to the adjacent uniformly sprayed strips.CONCLUSIONSFrom an ecological and economical point of view, the sensor-controlled variable-rate spraying technology, which uses the green crop coverage level as plant parameter for adapting the spray volume locally, can be an alternative to the common practice of uniform spraying.
      PubDate: 2017-12-28T11:05:27.686535-05:
      DOI: 10.1002/ps.4843
  • Development of an attract-and-kill co-formulation containing Saccharomyces
           cerevisiae and neem extract attractive towards wireworms
    • Authors: Pascal Humbert; Marina Vemmer, Frauke Mävers, Mario Schumann, Stefan Vidal, Anant V Patel
      Abstract: BACKGROUNDWireworms (Coleoptera: Elateridae) are major insect pests of world-wide relevance. Due to the progressive phasing-out of chemical insecticides, there is a great demand for innovative control options. This study reports on the development of an attract-and-kill co-formulation based on Ca-alginate beads, which release CO2 and contain neem extract as a bioinsecticidal compound. Our objectives were to figure out, (i) whether neem extract can be efficiently immobilized, (ii) whether CO2-releasing Saccharomyces cerevisiae and neem extract are suitable for co-encapsulation, and (iii) whether co-encapsulated neem extract affects the attractiveness of CO2-releasing beads towards wireworms.RESULTSNeem extract was co-encapsulated together with S. cerevisiae, starch and amyloglucosidase with a high encapsulation efficiency of 98.6% (based on the measurement of azadirachtin A as main active ingredient). Even in enhanced concentrations, neem extract allowed growth of S. cerevisiae and beads containing neem extract exhibited a comparable CO2-emission as beads without neem extract. When applied into the soil, the beads established a CO2 gradient spanning more than 15 cm. The co-formulation containing neem extract showed no repellent effects and was attractive for wireworms within the first 24 h after exposure.CONCLUSIONCo-encapsulation of S. cerevisiae and neem extract is a promising approach for the development of attract-and-kill formulations for the control of wireworms. This study offers new options for the application of neem extracts in soil.
      PubDate: 2017-12-27T08:31:46.586385-05:
      DOI: 10.1002/ps.4842
  • Assessing the current and future biological control potential of
           Trichogramma ostriniae on its hosts Ostrinia furnacalis and Ostrinia
    • Authors: Li-Hsin Wu; Matthew P. Hill, Linda J. Thomson, Ary A. Hoffmann
      Abstract: BACKGROUNDUnderstanding interactions between biocontrol agents and their pest hosts under climate change should assist implementation of biocontrol strategies, by identifying appropriate biocontrol agents for release or determining the optimal timing of releases. Species Distribution Models (SDMs) are applied to evaluate the distributions of Trichogramma ostriniae and its native host, Ostrinia furnacalis, in southeastern Asia, and a non-native host, Ostrinia nubilalis, in a novel range, North America, using MAXENT and CLIMEX modelling approaches.RESULTSBoth models led to similar predictions about the expected distribution of the two species in Asia, and emphasized likely mismatches between host and natural enemy. Trichogramma ostriniae was predicted to occur in the summer corn region of China, with distribution limits linked to its sensitivity to cold, seasonality of radiation and precipitation. Modelled Ostrinia nubilalis distribution overlaps with the main corn production areas of northeastern United States and Canada; temporary/seasonal suitable habitat was predicted across southeastern states as well. Climate change scenarios are predicted to favor T. ostriniae over its hosts in northeastern China and North America.CONCLUSIONSThe modelling approaches used here proved useful for assessing environmental factors linked to an egg parasitoid and its lepidopteran hosts and identifying areas potentially suitable for inundative releases.
      PubDate: 2017-12-27T02:00:23.579725-05:
      DOI: 10.1002/ps.4841
  • First evidence of resistance to pyrethroid insecticides in Italian Aedes
           albopictus populations after 26 years since invasion
    • Authors: Verena Pichler; Romeo Bellini, Rodolfo Veronesi, Daniele Arnoldi, Annapaola Rizzoli, Riccardo Paolo Lia, Domenico Otranto, Fabrizio Montarsi, Sara Carlin, Marco Ballardini, Elisa Antognini, Marco Salvemini, Emanuele Brianti, Gabriella Gaglio, Mattia Manica, Pietro Cobre, Paola Serini, Enkelejda Velo, John Vontas, Ilias Kioulos, Joao Pinto, Alessandra della Torre, Beniamino Caputo
      Abstract: BACKGROUNDAedes albopictus has spread during the last decades all over the world. This has increased significantly the risk of exotic arbovirus transmission (e.g. Chikungunya, Dengue, and Zika) also in temperate areas, as testified by the Chikungunya 2007- and 2017-outbreaks in north-east and central Italy. Insecticides represent a main tool for limiting the circulation of these mosquito-borne viruses. The aim of the present study is to start filling the current gap of knowledge on pyrethroid insecticide resistance of European Ae. albopictus populations focusing on populations from Italy, Albania and Greece.RESULTSBioassays for resistance to permethrin (0.75%), α-cypermethrin (0.05%) or deltamethrin (0.05%) were performed according to WHO protocols and showed reduced susceptibility (
      PubDate: 2017-12-26T10:50:23.285849-05:
      DOI: 10.1002/ps.4840
  • Factors driving public tolerance levels and information seeking behaviour
           concerning insects in the household environment
    • Authors: Bruce Schoelitsz; P. Marijn Poortvliet, Willem Takken
      Abstract: BACKGROUNDThe public's negative attitudes towards household insects, drive tolerance for these insects and their control. Tolerance levels are important in IPM, as are pest knowledge and information. The Risk Information Seeking and Processing (RISP) model describes the relationships between personal factors and information seeking behaviour. We combined IPM and RISP to determine important relationships between factors driving insect tolerance levels and information seeking behaviour through an online survey and tested whether this model is valid and generally applicable.RESULTSRelationships between variables from both IPM and RISP models were tested for seven insect species. Tolerance levels were measured with two factors: (1) willingness to pay for pest control and (2) whether insects are tolerated. Willingness to pay for control was positively affected by age, experience, risk perception, insect characteristics, and negative emotions and affected behavioural intention by influencing information sufficiency, and information seeking behaviour. Tolerability is influenced by perception of insect characteristics and determines whether control measures are taken.CONCLUSIONIt was possible to combine the RISP and IPM models. Relevant driving factors were a person's age, experience, risk perception, negative affective responses, tolerance levels, relevant channel beliefs of online forums, information sufficiency and information seeking behaviour. There is, however, variation in important factors between different insects.
      PubDate: 2017-12-23T01:25:22.052015-05:
      DOI: 10.1002/ps.4839
  • Zoophytophagous mirids provide pest control by inducing direct defences,
           antixenosis and attraction to parasitoids in sweet pepper plants
    • Authors: Sarra Bouagga; Alberto Urbaneja, José L. Rambla, Víctor Flors, Antonio Granell, Josep A. Jaques, Meritxell Pérez-Hedo
      Abstract: BACKGROUNDIn addition to their services as predators, mirid predators are able to induce plant defences by phytophagy. However, whether this induction occurs in sweet pepper and whether it could be an additional benefit to their role as biological control agent in this crop remains unknown. Here, these questions are investigated in two model insects, the mirids Nesidiocoris tenuis and Macrolophus pygmaeus.RESULTSPlant feeding behaviour was observed in both N. tenuis and M. pygmaeus on sweet pepper and occupied 33% and 14% of total time spent on the plant respectively. The punctures caused by mirid plant feeding induced the release of a blend of Volatile Organic Compounds (VOCs) which repelled the herbivore pests Frankliniella occidentalis and Bemisia tabaci and attracted the whitefly parasitoid Encarsia formosa. The repellent effect on B. tabaci was observed for at least 7 days after initial exposure of the plant to N. tenuis, and attraction of E. formosa remained functional for 14 days.CONCLUSIONFeeding induced plant defences by mirid predators, their subsequent effects on both pests and natural enemy behaviour, and the persistence of these observed effects open the door to new control strategies in sweet pepper crop. Further application of this research is discussed, such as the vaccination of plants by zoophytophagous mirids in the nursery before transplantation.
      PubDate: 2017-12-23T00:30:35.410916-05:
      DOI: 10.1002/ps.4838
  • The Y137H mutation in the FgCYP51B protein confers reduced sensitivity to
           tebuconazole in Fusarium graminearum
    • Authors: Hengwei Qian; Juan Du, Mengyu Chi, Xiaomei Sun, Wenxing Liang, Jinguang Huang, Baodu Li
      Abstract: BACKGROUNDFusarium graminearum is the main pathogen of Fusarium Head Blight (FHB), a worldwide plant disease and one of the most significant wheat diseases in China. Demethylation inhibitor (DMI) fungicides, such as tebuconazole (TEC), are widely used to control FHB, but long-term use leads to low efficacy against FHB. Earlier studies showed that DMI resistance is associated with the fungal sterol 14α-demethylase (CYP51) gene, and that point mutations in the CYP51 gene are the primary mechanism of resistance to DMI fungicides. The aims of this study were to clarify the molecular mechanisms of resistance to TEC and identify the binding sites on the FgCYP51B protein.RESULTSSite-directed mutagenesis was used to change the FgCYP51B gene of wide-type strain PH-1 from tyrosine to histidine at residue 137 (Y137H) to generate mutant transformant, which was confirmed to be resistant to TEC compared to the parental strains. A three-dimensional FgCYP51B model was constructed, and molecular docking simulation studies were conducted to identify the optimum binding mode with TEC. The wild-type FgCYP51B protein displayed stronger affinity to TEC than that of the mutational FgCYP51B in the molecular docking analysis.CONCLUSIONThese results indicate that a Tyr137 amino acid mutation in the FgCYP51B gene could lead to resistance to TEC and that Y137 forms part of the tebuconazole binding pocket.
      PubDate: 2017-12-23T00:11:03.583524-05:
      DOI: 10.1002/ps.4837
  • Reducing Drosophila suzukii emergence through inter-species competition
    • Authors: Bethan Shaw; Philip Brain, Herman Wijnen, Michelle T Fountain
      Abstract: BACKGROUNDDrosophila suzukii has dispersed widely from its native Asian range since 2008. Its arrival in the UK is resulting in economic losses in soft- and stone-fruit crops caused by larvae feeding on the flesh of ripening fruit. Although a large amount of research has been directed at controlling this pest, it is presently unknown how this invasive species interacts with native Drosophila species.RESULTSIn the work reported here Drosophila suzukii or Drosophila melanogaster adults were introduced to substrates, pre-inoculated with the eggs of the same or other species in a laboratory choice assay. D. melanogaster adult emergence was not affected by the pre-inoculation of D. suzukii. D. suzukii was significantly lower from media pre-inoculated by D. melanogaster than from blank media. In a following experiment, significantly more D. suzukii eggs were laid in blank media than in D. melanogaster pre-inoculated media.CONCLUSIONThe presence of D. melanogaster in a substrate significantly reduced D. suzukii emergence and egg laying. This study opens future research questions on how this reduction mechanism is driven and how it could be exploited as part of future Integrated Pest Management practices.
      PubDate: 2017-12-20T04:05:23.318962-05:
      DOI: 10.1002/ps.4836
  • Characterisation of imidacloprid resistance in the bird cherry-oat aphid,
           Rhopalosiphum padi, a serious pest on wheat crops
    • Authors: Kang Wang; Meng Zhang, Yanna Huang, Zhuolin Yang, Sha Su, Maohua Chen
      Abstract: BACKGROUNDRhopalosiphum padi is a destructive insect pest of wheat worldwide. Studies have shown that R. padi has developed resistance to different insecticides, including imidacloprid. We studied the mechanisms conferring resistance to imidacloprid at the biochemical and molecular levels.RESULTSAn R. padi imidacloprid-resistant (IM-R) strain and a susceptible strain (SS) were established. Fitness analysis using life-tables showed that the IM-R strain had obvious disadvantages in several parameters, indicating reduced fitness. Cross-resistance profiles of IM-R and SS to seven insecticides were detected. Both synergistic and enzyme activity data suggested that P450 plays role in resistance. Furthermore, the mRNA expression levels of CYP6CY3-1 and CYP6CY3-2 were significantly increased in the IM-R strain. No target-site mutation within the nicotinic acetylcholine receptor (nAChR) subunits was detected in the IM-R strain. Interestingly, the expression levels of the nAChR α1, α2, α3, α7-2, and β1 subunit genes were significantly decreased, suggesting that down-regulation of these subunits may be involved in resistance.CONCLUSIONMultiple mechanisms confer imidacloprid resistance in R. padi.
      PubDate: 2017-12-19T21:45:57.347794-05:
      DOI: 10.1002/ps.4834
  • Occurrence of target-site resistance to neonicotinoids in the aphid Myzus
           persicae in Tunisia, and its status on different host plants
    • Authors: Kamel Charaabi; Sonia Boukhris-Bouhachem, Mohamed Makni, Ian Denholm
      Abstract: BACKGROUNDThe R81T mutation conferring target site resistance to neonicotinoid insecticides in Myzus persicae was first detected in France and has since spread across much of southern Europe. In response to recent claims of control failure with neonicotinoids in Tunisia, we have used a molecular assay to investigate the presence and distribution of this target site mutation in samples collected from six locations and six crops attacked by M. persicae.RESULTSThe resistance allele containing R81T was present at substantial frequencies (32-55%) in aphids collected between 2014 and 2016 from northern Tunisia but was much rarer further south. It occurred in aphids collected from the aphid's primary host (peach) and four secondary crop hosts (potato, pepper, tomato and melon). Its absence in aphids from tobacco highlights complexities in the systematics of M. persicae that require further investigation.CONCLUSIONThis first report of R81T from North Africa reflects a continuing expansion of its range around the Mediterranean Basin although it remains unrecorded elsewhere in the world. Loss of efficacy of neonicotinoids presents a serious threat to the sustainability of aphid control.
      PubDate: 2017-12-19T21:17:09.653515-05:
      DOI: 10.1002/ps.4833
  • Soybean seed coat chitinase as a defense protein against stored product
           pest Callosobruchus maculatus
    • Authors: Nadia C. M. Silva; Jamile G. Conceição, Kayan Eudorico Ventury, Leonardo F. R. De Sá, Eduardo A. G. Oliveira, Izabela S. Santos, Valdirene M. Gomes, Monique N. Costa, Andre T. S. Ferreira, Jonas Perales, Jose Xavier-Filho, Kátia V. S. Fernandes, Antonia E. A. Oliveira
      Abstract: BACKGROUNDChitinases (EC are enzymes involved in the breaking of β-1,4-glycosidic linkages of chitin. In insects, chitin is present mainly in cuticle and in peritrophic membranes and peritrophic gel. Enzymes with the potential to damage peritrophic membranes and gel, such as chitinase, have been related to plant defense systems. Identification and characterisation of seed coat chitinase as a plant defensive molecule may indicate a more effective target for manipulation strategies, which may lead to the preventive consumption of embryonic tissues by the larvae and consequently the minimization of the seed damage.RESULTSWe studied the efficiency of soybean seed coat chitinase as a defense molecule against Callosobruchus maculatus insect. The seed coat chitinase was isolated and identified by mass spectrometry, immunoreacted with an anti-chitinase antibody and showed activity against chitin azure and 4-Methylumbelliferyl β-D-N,N′,N′′- triacetylchitotrioside. A chitinase fraction incorporated in artificial cotyledons at 0.1 % reduced larval survival about 77 % and at 0.5 %, the larval weight loss was 60 %. Chitinase FITC-labeled was detected in gut and feces of larvae. At 25 % in tick artificial seed coats chitinase showed a high toxicity to larvae, with mortality of 90 % and reduction of larval mass of 87 %.CONCLUSIONSeed coat chitinase is an important seed defensive molecule not only in the cotyledons, but also in the seed coats, acting as a part of the array of defense against Callosobruchus maculatus.
      PubDate: 2017-12-18T02:20:55.631028-05:
      DOI: 10.1002/ps.4832
  • Protein identification before and after glyphosate exposure in Lolium
           multiflorum genotypes
    • Authors: Arthur AM Barroso; Marilia G de S Costa, Nelson J Neto, Juciléia I dos Santos, Tiago S Balbuena, Caio A Carbonari, Pedro LCA Alves
      Abstract: BACKGROUNDWeeds reduce crop yields, and among the methods used to control these plants, chemical use is preferred. However, the repeated application of herbicides with the same mechanism of action selects for resistant populations. The aim of this study was to evaluate glyphosate resistance in Lolium multiflorum (Lam.) and relate the resistance to protein expression in the absence and presence of the herbicide using a metabolic-proteomic approach.RESULTSGlyphosate resistance was confirmed, with a sevenfold difference in resistance between susceptible and resistant genotypes. Among the possible mechanisms affecting resistance, mutations in the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), herbicide differential translocation and overexpression of EPSPS are suggested. Susceptible plants had higher growth than did resistant plants in the absence of the herbicide, in addition to greater expression of protein groups related to photosynthesis and to tolerance to biotic and abiotic stresses. With application of glyphosate, resistant plants maintained their metabolism and began to express EPSPS and other candidate proteins related to herbicide resistance.CONCLUSIONSIn the absence of glyphosate, the susceptible plants would replace the resistant plants over time, and abiotic or biotic stresses would accelerate this process. Resistance in plants resulted from a combination of target-site and non-target-site resistance mechanisms. We identified several candidate proteins that could be investigated in future studies on glyphosate resistance.
      PubDate: 2017-12-18T01:30:46.879279-05:
      DOI: 10.1002/ps.4831
  • Dynamics of Bed Bug Infestations in Three Low-Income Housing Communities
           with Various Bed Bug Management Programs
    • Authors: Changlu Wang; Amanda Eiden, Narinderpal Singh, Chen Zha, Desen Wang, Richard Cooper
      Abstract: BACKGROUNDInfestations of the common bed bug, Cimex lectularius L., have become common in low-income communities in the United States over the last 15 years. We evaluated community-based integrated pest management (IPM) programs for reducing bed bug infestations. Two housing authorities (Bayonne and Hackensack) implemented bed bug IPM programs. A third housing authority (Paterson) was used as the control site. Building-wide surveys were conducted in all communities, three times, to evaluate the effectiveness of the IPM programs.RESULTSFrom 0 mo to 24 mo, the infestation rate at Bayonne, Hackensack, and Paterson decreased by 49, 64, and 26%, respectively. The two sites that adopted IPM achieved faster bed bug elimination than the control site. The bed bug introduction rate over a 24 mo period at Bayonne, Hackensack, and Paterson was 7, 3, and 11%, respectively. The introduction rate was positively associated with the initial infestation rate. Residents from buildings enrolled in IPM programs were more satisfied with the bed bug control services than residents from the control site.CONCLUSIONIPM programs were more effective in reducing bed bug infestations than traditional pest control services, but many factors contributed to the lower than desired level of reduction in infestation rate.
      PubDate: 2017-12-15T05:34:16.373563-05:
      DOI: 10.1002/ps.4830
  • Insecticide susceptibility status of invasive Aedes albopictus across
           dengue endemic districts of Odisha, India
    • Authors: Animesha Rath; Ipsita Mohanty, Rupenangshu K Hazra
      Abstract: BACKGROUNDAedes albopictus is currently the most invasive mosquito species in the world. Keeping in view the wide emergence of insecticide resistance, it is imperative to focus on the current susceptibility status for various insecticides in Ae. albopictus. The present study is focused on understanding the insecticide resistance mechanism of Ae. albopictus collected from dengue endemic districts of Odisha.RESULTSInsecticide resistance was evaluated by using standardized bioassay kits (WHO) and biochemical analysis. Larval bioassays revealed the highest level of resistance from JP population with RR50 of 15.3 and LC50 of 1.177ppm compared to LC50 of 0.077 for the susceptible strain LabS. Results indicated the presence of DDT resistance in the majority of adult populations. Elevated activity of non specific esterases and P450s MFO indicated probable resistance to organophosphates and pyrethroids. Molecular screening for common insecticide target-site mutations confirmed the absence of the “knock down resistance” response for pyrethroid insecticide in Ae. albopictus population suggesting its continual effectiveness as the major insecticide of significant importance in future vector control programmes.CONCLUSIONThis is the first report of a kdr mutation in Ae. albopictus in India and highlights the need for intensive research on other unexplored target site mutations that might also contribute to pyrethroid resistance. Effective management and sustainable use of insecticides can be implemented by understanding resistance mechanisms and development of appropriate diagnostic tools.
      PubDate: 2017-12-14T07:20:30.849529-05:
      DOI: 10.1002/ps.4827
  • Without or without pheromone habituation: Possible differences between
           insect orders'
    • Authors: David Maxwell Suckling; Lloyd D Stringer, Alfredo Jiménez-Pérez, Gimme H. Walter, Nicola Sullivan, Ashraf M El-Sayed
      Abstract: BackgroundHabituation to sex pheromones is one of the key mechanisms in mating disruption, an insect control tactic. Male moths often show reduced sexual response after pre-exposure to female sex pheromone. Mating disruption is relatively rare in insect orders other than Lepidoptera.ResultsAs a positive control we confirmed habituation in a moth (Epiphyas postvittana) using 24 h pre-exposure to sex pheromone to reduce subsequent activation behaviour. We then tested the impact of pre-exposure to sex or trail pheromone on subsequent behavioural response with insects from three other orders. Similar pre-exposure for 24 h to either sex pheromone (Pseudococcus calceolariae (Homoptera) and apple leaf curling midge Dasineura mali (Diptera), or trail pheromone of Argentine ants (Linepithema humile (Hymenoptera)), followed by behavioural assay in clean air provided no evidence of habituation after pre-exposure in these latter cases.ConclusionsThe moths alone were affected by pre-exposure to pheromone. For pests without habituation, sustained attraction to a point source may make lure and kill more economical. Improved knowledge of behavioural processes should lead to better success in pest management and mechanisms should be investigated further to inform studies and practical efforts generally enhancing effectiveness of pheromone-based management.
      PubDate: 2017-12-14T06:20:28.810568-05:
      DOI: 10.1002/ps.4828
  • Inheritance and fitness costs of Spodoptera frugiperda (Lepidoptera:
           Noctuidae) resistance to spinosad in Brazil
    • Authors: Daniela M. Okuma; Daniel Bernardi, Renato J. Horikoshi, Oderlei Bernardi, Aline P. Silva, Celso Omoto
      Abstract: BACKGROUNDSpodoptera frugiperda is a pest of economically important crops in the South America. In Brazil, this species is considered the most destructive pest of maize. The use of spinosyn insecticides in Insect Resistance Management (IRM) has been one of the strategies to control this pest. In this study, we selected a resistant strain of S. frugiperda to spinosad and evaluated the inheritance and fitness costs of the resistance.RESULTSThe estimated LC50 values were 0.011 and 9.80 μg ai cm2 for the spinosad-susceptible (Sus) and -resistant (Spin-res) strains, respectively. This represents an 890-fold resistance ratio. The LC50 values for reciprocal crosses were 0.18 and 0.14 μg ai cm2, indicating that resistance to spinosad is an autosomal incompletely recessive trait. Backcrosses of the F1 progeny from reciprocal crosses with the parental Spin-res strain showed a polygenic effect. The estimated minimum number of independent segregations was approximately 2.45, indicating that resistance to spinosad is associated with multiple genes. In greenhouse assays, third instar larvae from Spin-res strain showed more than 92% survivorship on spinosad-treated maize. In contrast Sus and reciprocal crosses exhibited 0 and
      PubDate: 2017-12-14T06:05:50.917243-05:
      DOI: 10.1002/ps.4829
  • Chlorantraniliprole resistance and its biochemical and new molecular
           target mechanisms in laboratory and field strains of Chilo suppressalis
    • Authors: Sun Yang; Lu Xu, Chen Qiong, Wenjing Qin, Huang Shuijin, Houguo Qin
      Abstract: BackgroundThe rice striped stem borer (SSB), Chilo suppressalis (Walker), is one of the most economically important and destructive rice pests in China. To date, the efficiency of conventional insecticides has decreased greatly because of the development of high resistance. Since the introduction of chlorantraniliprole in 2008, SSB has presented resistance issues.ResultsIn this study, lab resistant strains R1 and R2 (RR of 38.8 and 110.4, respectively) were established and a field population HR (RR of 249.6) was collected. Synergists assessment and enzyme activity data suggested potential involvement of P450s and esterases in resistance mechanism. No target (ryanodine receptor, RyR) mutation was found in R1, but a novel mutation Y4667D was found in R2. At the same position of RyR in HR strain, Y4667D and Y4667C were observed at low frequencies. Besides, the conserved mutation I4758M was found with a frequency of 94.4%. RyR mRNA expression was significantly lower in R1, R2, and HR than in S. Treated with chlorantraniliprole, RyR mRNA expression in all four strains was downregulated to ~50%.ConclusionsA comprehensive analysis, including biochemical, target mutations, and target mRNA expression, was conducted trying to interpret chlorantraniliprole resistance mechanism in both lab and field SSB strains.
      PubDate: 2017-12-13T06:16:21.072955-05:
      DOI: 10.1002/ps.4824
  • Weed Resistance to Synthetic Auxin Herbicides
    • Authors: Roberto Busi; Danica E. Goggin, Ian Heap, Michael J. Horak, Mithila Jugulam, Robert A. Masters, Richard Napier, Dilpreet S. Riar, Norbert M. Satchivi, Joel Torra, Phillip Westra, Terry R. Wright
      Abstract: Herbicides classified as synthetic auxins have been most commonly used to control broadleaf weeds in a variety of crops and in non-cropland areas since the first synthetic auxin herbicide (SAH), 2,4-D, was introduced to the market in the mid-1940s. The incidence of weed species resistant to SAHs is relatively low considering their long-term global application with 29 broadleaf weed species confirmed resistant to date. An understanding of the context and mechanisms of SAH resistance evolution can inform management practices to sustain the longevity and utility of this important class of herbicides. A symposium was convened during the 2nd Global Herbicide Resistance Challenge (May 2017 in Denver, CO, USA) to provide an overview of the current state of knowledge of SAH resistance mechanisms including case studies of weed species resistant to SAHs and perspectives on mitigating resistance development in SAH-tolerant crops.
      PubDate: 2017-12-13T05:50:40.185203-05:
      DOI: 10.1002/ps.4823
  • Chimeric Mice with Humanized Liver as a Model for Testing Organophosphate
           and Carbamate Pesticide Exposure
    • Authors: Hiroshi Suemizu; Kenji Kawai, Norie Murayama, Masato Nakamura, Hiroshi Yamazaki
      Abstract: BACKGROUNDDiagnosis of acute intoxication with organophosphate (OP) or carbamate (CM) pesticides in humans is achieved by measuring plasma butyrylcholinesterase (BuChE) activity. However, BuChE activity is not an ideal biomarker in experimental animal models. The aim of this study was to establish an experimental mouse model for evaluating exposure to OP and CM pesticides by monitoring BuChE activity using chimeric mice in which the liver was reconstituted with human hepatocytes.RESULTSA single oral administration of acephate (300 mg/kg), chlorpyrifos (10 mg/kg), fenobucarb (300 mg/kg) or molinate (250 mg/kg) in chimeric mice led to inhibition of>95%,>95%, 28%, and 60% of plasma BuChE activity after 7 h, 0.5 h, 0.5 h, and 7 h, respectively. Dose-dependent decreases in plasma BuChE activity were also observed for acephate and chlorpyrifos. A 5-day repeated-dose study with 10 or 30 mg/kg acephate found a constitutive reduction in plasma BuChE activity to 80% and 70% of predose levels, respectively.CONCLUSIONChanges in plasma BuChE activity in chimeric mice with humanized liver clearly reflected the exposure levels of OP and CM pesticides. These results suggest that the humanized-liver mouse model may be a suitable model for estimating exposure levels to these pesticides in humans.
      PubDate: 2017-12-13T05:40:17.62812-05:0
      DOI: 10.1002/ps.4825
  • The Challenge of Herbicide Resistance Around the World: A Current Summary
    • Authors: Mark A. Peterson; Alberto Collavo, Ramiro Ovejero, Vinod Shivrain, Michael J. Walsh
      Abstract: Herbicide resistant weeds have been observed since the early years of synthetic herbicide development in the 1950's and 1960's. Since that time there has been a consistent increase in the number of herbicide resistance cases and the impact of herbicide resistant (HR) weeds. While the nature of crop production varies widely around the world, herbicides have become a primary tool for weed control in most areas. Dependence on herbicides continues to increase as global populations migrate away from rural areas into cities and the agricultural labor force declines. This increased use of herbicides and concurrent selection pressure has resulted in a rise in cases of multiple resistance leaving some farmers with few or no herbicide options for certain weed infestations. Global population and economic forces drive many farmer choices regarding crop production and weed control. The challenge is how to insert best management practices into the decision making process while addressing various economic and regulatory needs. This review endeavors to provide a current overview of herbicide resistance challenges in the major crop production areas of the world and discusses some research initiatives designed to address portions of the problem.
      PubDate: 2017-12-09T10:30:47.805316-05:
      DOI: 10.1002/ps.4821
  • Optimizing RNA-seq studies to investigate herbicide resistance
    • Authors: Darci A Giacomini; Todd Gaines, Roland Beffa, Patrick J Tranel
      Abstract: Transcriptomic profiling, specifically via RNA-seq, is becoming one of the more commonly used methods for investigating non-target site resistance (NTSR) to herbicides due to its high throughput capabilities and utility in organisms with little to no previous sequence information. A review of the weed science RNA-seq literature has revealed some basic principles behind generating quality data from these types of studies. First, studies that included more replicates per biotype and took steps to control for genetic background had significantly better control of false positives and, consequently, shorter lists of potential resistance genes to sift through. Pooling of biological replicates prior to sequencing was successful in some cases, but likely contributed to an overall increase in the false discovery rate (FDR). While the inclusion of herbicide-treated samples was common across most of the studies, it ultimately introduced difficulties in interpretation of the final results due to challenges in capturing the right sampling window after treatment and due to induction of stress responses in the injured herbicide-sensitive plants. RNA-seq is an effective tool for NTSR gene discovery, but careful consideration should be given to finding the most powerful and cost-effective balance between replicate number, sequencing depth, and treatment number.
      PubDate: 2017-12-09T10:10:57.373781-05:
      DOI: 10.1002/ps.4822
  • Contrasting Patterns of Variation in Weedy Traits and Unique Crop Features
           in Divergent Populations of US Weedy Rice (Oryza sativa sp.) in Arkansas
           and California
    • Authors: Kimberly L. Kanapeckas; Te-Ming Tseng, Cynthia C. Vigueira, Aida Ortiz, William C. Bridges, Nilda R. Burgos, Albert J. Fischer, Amy Lawton-Rauh
      Abstract: BACKGROUNDWeed evolution from crops involves changes in key traits, but it is unclear how genetic and phenotypic variation contribute to weed diversification and productivity. Weedy rice is a conspecific weed of rice (Oryza sativa) worldwide. We used principal component analysis and hierarchical clustering to understand how morphologically and evolutionarily distinct US weedy rice populations persist in rice fields in different locations under contrasting management regimes. Further, we used a representative subset of 15 sequence-tagged-site fragments of expressed genes from global Oryza to assess genome-wide sequence variation among populations.RESULTSCrop hull color and crop-overlapping maturity dates plus awns, seed (panicle) shattering (>50%), pigmented pericarp, and stature variation (30.2% of total phenotypic variance) characterize genetically less diverse California weedy rice. In contrast, wild-like hull color, seed shattering (>50%), and stature differences (55.8% of total phenotypic variance) typify genetically diverse weedy rice ecotypes in Arkansas.CONCLUSIONRecent de-domestication of weedy species—such as in California weedy rice—can involve trait combinations indistinguishable from the crop. This underscores the need for strict seed certification with genetic monitoring and proactive field inspection to prevent proliferation of weedy plant types. In established populations, tillage practice may affect weed diversity and persistence over time.
      PubDate: 2017-12-05T04:55:24.056109-05:
      DOI: 10.1002/ps.4820
  • Herbicide resistance costs: what are we actually measuring and why'
    • Authors: Roger D Cousens; Alexandre Fournier-Level
      Abstract: Despite the considerable research efforts invested over the years to measure the fitness costs of herbicide resistance, these have rarely been used to inform a predictive theory about the fate of resistance once the herbicide is discontinued. One reason for this may be the reductive focus on relative fitness of two genotypes as a single measure of differential performance. Although the extent of variation in relative fitness between resistant and susceptible plants has not been assessed consistently, we know enough about plant physiology and ecology not to reduce it to a single fixed value. Research must therefore consider carefully the relevance of the experimental environment, the life stage and the choice of metric when measuring fitness-related traits. The reason most often given for measuring the cost of resistance, prediction of the impacts of management options on population dynamics, cannot be addressed using arbitrary components of fitness or a fixed value of relative fitness. To inform management options, the measurement of traits that capture the relevant processes and the main causes of their variation are required. With an emphasis on the benefit of field experiments measured over multiple time points and seasons, we highlight examples of studies that have made significant advances in this direction.
      PubDate: 2017-12-05T03:45:52.215673-05:
      DOI: 10.1002/ps.4819
  • Foliar application of benzovindiflupyr shows non-fungicidal effects in
           wheat plants
    • Authors: Dmitry Kuznetsov; Alexandre Brice Cazenave, Odile Rambach, Philippe Camblin, Mafalda Nina, Jörg Leipner
      Abstract: BACKGROUNDThe fungicide benzovindiflupyr belongs to the class of succinate dehydrogenase inhibitors (SDHIs). Certain SDHIs have shown plant physiological effects, so-called secondary effects, that appeared to be related to the plant water status. Therefore, the effect of benzovindiflupyr on transpiration of leaves and whole wheat plants was studied under controlled conditions. Furthermore, wheat yield trials under controlled and natural drought stress in the field were conducted.RESULTSTranspiration of detached wheat leaves was reduced by benzovindiflupyr in a dose-dependent manner. Similarly, whole-plant transpiration decreased for several days following application of this fungicide. In 16 field trials under drought stress conditions that were classified as disease-free, treatment of wheat plants at the flag leaf stage or at heading with benzovindiflupyr showed a grain yield increase (+5.2%; P ≤ 0.01) that was partially attributed to an increased thousand-grain weight.CONCLUSIONSWater saving during pre-anthesis as a result of benzovindiflupyr application may be associated with better seed setting and filling under dry field conditions in wheat. The results of this research provide new insights into secondary effects of SDHIs that lead directly to yield improvements. © 2017 The
      Authors . Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.Secondary effects of the SDHI fungicide benzovindiflupyr were studied in wheat. The product decreased plant transpiration and increased grain yield in disease free field trials under drought stress.
      PubDate: 2017-12-04T20:26:18.083223-05:
      DOI: 10.1002/ps.4754
  • Synergistic interactions between a variety of insecticides and an
           ergosterol biosynthesis inhibitor fungicide in dietary exposures of bumble
           bees (Bombus terrestris L.)
    • Authors: Risto Raimets; Reet Karise, Marika Mänd, Tanel Kaart, Sally Ponting, Jimao Song, James E Cresswell
      Abstract: BACKGROUNDIn recent years, concern has been raised over honey bee colony losses, and also among wild bees there is evidence for extinctions and range contractions in Europe and North America. Pesticides have been proposed as a potential cause of this decline. Bees are exposed simultaneously to a variety of agrochemicals, which may cause synergistically detrimental impacts, which are incompletely understood. We investigated the toxicity of the fungicide imazalil in mixture with four common insecticides: fipronil (phenylpyrazoid), cypermethrin (pyrethroid), thiamethoxam, and imidacloprid (neonicotinoids). Ergosterol biosynthesis inhibitor (EBI) fungicides like imazalil can inhibit P450 detoxification systems in insects and therefore fungicide − insecticide co-occurrence might produce synergistic toxicity in bees. We assessed the impact of dietary fungicide − insecticide mixtures on the mortality and feeding rates of laboratory bumble bees (Bombus terrestris L.).RESULTSRegarding mortality, imazalil synergised the toxicity of fipronil, cypermethrin and thiamethoxam, but not imidacloprid. We found no synergistic effects on feeding rates.CONCLUSIONOur findings suggest that P450-based detoxification processes are differentially important in mitigating the toxicity of certain insecticides, even those of the same chemical class. Our evidence that cocktail effects can arise in bumble bees should extend concern about the potential impacts of agrochemical mixtures to include wild bee species in farmland. © 2017 Society of Chemical IndustryFungicide imazalil synergized with some of the used insecticides which led to significant increase in bumble bee mortality after 48 hours.
      PubDate: 2017-12-04T20:26:13.854303-05:
      DOI: 10.1002/ps.4756
  • Advocating a need for suitable breeding approaches to boost Integrated
           Pest Management: A European perspective
    • Authors: Jay Ram Lamichhane; Edward Arseniuk, Piet Boonekamp, Jerzy Czembor, Veronique Decroocq, Jérome Enjalbert, Maria R. Finckh, Małgorzata Korbin, Mati Koppel, Per Kudsk, Akos Mesterhazy, Danuta Sosnowska, Ewa Zimnoch-Guzowska, Antoine Messéan
      Abstract: Currently, European farmers do not have access to a sufficient number and diversity of crop species/varieties. This prevents them from designing more resilient cropping systems to abiotic and biotic stresses. Crop diversification is a key lever to reduce pest (pathogens, animal pests and weeds) pressures at all spatial levels from fields to landscapes. In this context, plant breeding should consist of: i) increased efforts in the development of new or minor crop varieties to foster diversity of cropping systems, and ii) focus on more resilient varieties showing local adaptation. This new breeding paradigm, called here “breeding for Integrated Pest Management (IPM)”, may boost IPM – through the development of cultivars with tolerance or resistance to key pests – with an ultimate goal of reducing reliance on conventional pesticides. At the same time, this paradigm has legal and practical implications for future breeding programs, including those targeting sustainable agricultural systems. By putting these issues into the context, this paper presents the key outcomes of a questionnaire survey as well as experts’ views expressed during an EU workshop entitled “Breeding for IPM in sustainable agricultural systems”.
      PubDate: 2017-12-04T02:20:24.09887-05:0
      DOI: 10.1002/ps.4818
  • Cucurbitacin B acts a potential insect growth regulator by antagonizing
           20-hydroxyecdysone activity
    • Authors: Chuanshan Zou; Guifen Liu, Suning Liu, Shumin Liu, Qisheng Song, Jian Wang, Qili Feng, Yunling Su, Sheng Li
      Abstract: BACKGROUND20-hydroxyecdysone (20E), a crucial insect steroid hormone, can bind to its cognate nuclear receptor composed of ecdysone receptor (EcR) and ultraspiracle (USP) to activate expression of 20E-response genes, enabling subsequent metamorphosis. In this study, we tried to find out the steroid-like compounds that are able to block insect metamorphosis effectively and to provide useful information for biopesticide study. For this purpose, we screened 126 steroid-like compounds for possible 20E antagonists using a dual-luciferase reporter assay with Drosophila melanogaster Kc and Bombyx mori Bm12 cells.RESULTSAmong 126 steroid-like compounds, three cucurbitacins (CucB, D and E) were identified as 20E antagonists in both Kc and Bm12 cells. Notably, CucB caused significant molting defects and mortality in both B. mori and D. melanogaster larvae, and it also dramatically hindered larval growth of Helicoverpa armigera by its anti-feeding activity.CONCLUSIONIn vivo and in vitro experiments demonstrate that CucB acts a potential insect growth regulator by antagonizing 20E activity and thus blocking molting and metamorphosis induced by 20E signaling.
      PubDate: 2017-12-04T02:00:23.973957-05:
      DOI: 10.1002/ps.4817
  • Agrochemical lead optimization by scaffold hopping
    • Authors: Clemens Lamberth
      Abstract: Scaffold hopping, the exchange of a specific portion of a potential active ingredient with another substructure with the aim of finding isofunctional molecular structures with significantly different molecular backbones, often offers the chance in lead discovery or optimization to mitigate problems related to toxicity, intellectual property, and insufficient potency or stability. Scaffold hopping tools such as isosteric ring replacement including 1,3 nitrogen shift and cyclic imine–amide isosterism, but also ring opening and ring closure approaches, functional group isosterism, reversion of functional groups, chain shortening, chain lengthening, and scaffolds delivered by natural products, have become a permanent fixture of the innovation and optimization process in crop protection research. Their appropriate use will be explained through examples of success stories in the field of agrochemistry. Analogies to, but also differences from, the main categories of scaffold hopping in medicinal drug discovery are discussed. © 2017 Society of Chemical IndustryThe successful application of scaffold hopping tools like isosteric ring replacement, ring opening, ring closure, functional group isosterism and functional group reversion to the discovery and optimization of agrochemicals is explained
      PubDate: 2017-12-01T08:00:39.756731-05:
      DOI: 10.1002/ps.4755
  • Synthesis, biological evaluation and SAR analysis of novel
           poly-heterocyclic compounds containing pyridylpyrazole group
    • Authors: Bao-Lei Wang; Hong-Wei Zhu, Zheng-Ming Li, Li-Zhong Wang, Xiao Zhang, Li-Xia Xiong, Hai-Bin Song
      Abstract: BACKGROUNDIn recent years, pyridylpyrazole derivatives, such as pyridylpyrazole-containing anthranilic diamide have attracted much attention by virtue of their useful insecticidal properties and unique action mode. Moreover, some pyridylpyrazole-containing compounds have also been found to possess significant fungicidal activities. With the aim of discovering new bioactive agrochemicals for crop protection, a series of poly-heterocyclic compounds containing pyridylpyrazole and aziridine, or β-lactam, or thiazolinone moieties were synthesized.RESULTSA series of pyridylpyrazole-containing poly-heterocyclic compounds were obtained, and confirmed through IR, 1H NMR, 13C NMR, HRMS and elemental analysis. The crystalline structure of 4-(3-bromo-1-(3-chloropyridin-2-yl)-1H-pyrazol-5-yl)-3-chloro-1-mesitylazetidin-2-one (compound 13f) was determined to further illustrate a trans- configuration of the β-lactam motif. In addition, bioassays showed that most of these new compounds exhibited modest insecticidal activity towards Mythimna separate Walker at 200 µg mL−1. Some of the compounds displayed excellent fungicidal activity towards some plant fungi, including Cercospora arachidicola (13j: EC50 = 14.5 µg mL−1), Physalospora piricola (12d and 13d: EC50 = 10.5 and 9.70 µg mL−1), Alternaria solani Sorauer (13j: EC50 = 7.29 µg mL−1), Puccinia sorghi Schw. (13d: control efficacy 99.0 ± 2.1% at 200 µg mL−1) and Erysiphe graminis (14d: control efficacy 95.0 ± 1.4% at 200 µg mL−1).CONCLUSIONCompounds 12b–12e, 13a, 13d, 13f, 13j, 13 k and 14d could be considered potential fungicidal lead compounds to do further structural optimization. The structure–activity relationship analysis in this study brings some new understanding to the biological activities of N-pyridylpyrazole-containing compounds, and provides important information for the research and development of novel agricultural fungicides with poly-heterocyclic structures. © 2017 Society of Chemical IndustryThere is a continuing need for the discovery and development of new agrochemicals for crop protection. This article presents synthesis and biological activity studies of novel pyridylpyrazole-containing poly heterocyclic compounds.
      PubDate: 2017-12-01T04:16:35.049611-05:
      DOI: 10.1002/ps.4770
  • Toxicity to and egg-laying avoidance of Drosophila suzukii (Diptera:
           Drosophilidae) caused by an old alternative inorganic insecticide
    • Authors: Felipe Andreazza; Henry E Vacacela Ajila, Khalid Haddi, Felipe Colares, Angelo Pallini, Eugênio E Oliveira
      Abstract: BACKGROUNDThe application of synthetic insecticides remains the most used tool for the management of spotted-wing drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). However, management of this pest in the organic production of soft-skinned fruits is a complex task due to the restricted number of registered products. Here, we assess the toxicity of lime sulfur and evaluate whether lime sulfur-treated strawberry plants affected the oviposition and development of D. suzukii.RESULTSLime sulfur exhibited adequate toxicity to D. suzukii (LC50 = 26.6 mL L−1) without phytotoxicity to strawberry plants. When D. suzukii females were exposed to lime sulfur-treated plants in no-choice bioassays, oviposition was significantly (t-test, P < 0.05) reduced compared with that on untreated plants. In free-choice bioassays, D. suzukii females laid significantly (paired t-test, P < 0.05) more eggs on untreated plants. Furthermore, in the free-choice bioassays, immature development was slower for adults that originated from eggs laid on lime sulfur-treated plants than from those laid on untreated plants.CONCLUSIONSLime sulfur showed adequate control and, therefore, has potential for use as a management tool against D. suzukii infestations in organic production systems. This old, alternative insecticide preparation not only caused adult fly mortality, but also reduced the number of eggs laid on lime sulfur-treated plants. © 2017 Society of Chemical IndustryThe present investigation assessed the toxicity of an old, alternative insecticide preparation (i.e., lime-sulfur) and evaluated whether lime-sulfur-treated strawberry plants affected the oviposition and development of Drosophila suzukii.
      PubDate: 2017-12-01T04:15:30.36692-05:0
      DOI: 10.1002/ps.4772
  • Sublethal effects of four insecticides on folding and spinning behavior in
           the rice leaffolder, Cnaphalocrocis medinalis (Guenée) (Lepidoptera:
    • Authors: Yajun Yang; Caiyun Wang, Hongxing Xu, Zhongxian Lu
      Abstract: BACKGROUNDThe rice leaffolder, Cnaphalocrocis medinalis, is an important rice pest. The sublethal effects of chlorpyrifos, chlorantraniliprole, emamectin benzoate and spinosad were investigated on the folding and spinning behaviors of third- to fifth-instar C. medinalis larvae (L3 − L5) after insecticidal exposure of the second instar.RESULTSA 25% lethal concentration (LC25) of chlorpyrifos prolonged the leaf selection time of L5, and reduced the number of binds per primary fold for L4 and L5. An LC10 of chlorantraniliprole reduced the number of binds per primary fold for L4 and increased the number of head swings per bind for L5. An LC10 of emamectin benzoate shortened the primary fold length for L5 and decreased the number of head swings per primary fold for L3 and L4 and the number of head swings per bind for L3, while an LC25 of emamectin benzoate shortened the fold length per 24 h for L5 and folding time for L3. An LC10 of spinosad lowered the fold length per 24 h and the number of head swings for L5. An LC25 of spinosad prolonged leaf selection time, and decreased primary fold length, binds per primary fold, binds per fold and fold length per 24 h in L5.CONCLUSIONEmamectin benzoate and spinosad exerted stronger sublethal effects on the folding and spinning behavior of C. medinalis than chlorpyrifos and chlorantraniliprole. These results provide better understanding of the sublethal effects of interactions of insecticides on C. medinalis. © 2017 Society of Chemical IndustryBehavior is an important trait for pests. This article presents the changes on folding and spinning behavior in Cnaphalocrocis medinalis after the treatments of sublethal concentrations of the four insecticides.
      PubDate: 2017-12-01T04:10:21.698404-05:
      DOI: 10.1002/ps.4753
  • Material properties determining the insecticidal activity of highly
           divided porous materials on the pharaoh ant (Monomorium pharaonis)
    • Authors: Heleen Van Den Noortgate; Bert Lagrain, Sreeprasanth Pulinthanathu Sree, Stef Kerkhofs, Tom Wenseleers, Johan A. Martens
      Abstract: BACKGROUNDHistorically, inert insecticidal powders such as diatomaceous earth were researched for pest management applications, revealing that these types of powders killed insects by desiccation. However, data on the critical material properties that affect their efficacy is sparse. The present study investigates the insecticidal effect of powdered materials on the pharaoh ant, a notorious domestic pest.RESULTSThe insecticidal activity of 24 porous materials was tested. 8 of these materials performed better than the benchmark, diatomaceous earth. Zeolite Y and carbon black II performed best, inducing 50% mortality within 40 minutes and 55 minutes respectively. Statistical analysis of 7 material properties revealed that macroporous surface area and BET specific surface area were most predictive of insecticidal activity. For zeolites and ordered mesoporous silica materials the most important parameters were respectively BET and large mesopore surface area. Finally, GC-MS analysis confirmed the adsorption of epicuticular hydrocarbons onto the zeolite powders.CONCLUSIONThis study shows clear potential for the use of environmentally friendly, inert porous materials as insecticides against the pharaoh ant and identified the key material properties influencing insecticidal activity. The GC-MS data supports the hypothesis that the mortality was caused by the removal of the protective epicuticular hydrocarbons.
      PubDate: 2017-12-01T02:00:25.278471-05:
      DOI: 10.1002/ps.4814
  • Overexpression of cytochrome P450 CYP6BG1 may contribute to
           chlorantraniliprole resistance in Plutella xylostella (L.)
    • Authors: Xiuxia Li; Ran Li, Bin Zhu, Xiwu Gao, Pei Liang
      Abstract: BACKGROUNDThe diamondback moth Plutella xylostella (L.) is the most widely distributed pest of cruciferous crops and has developed resistance to most commonly used insecticides, including chlorantraniliprole. Resistance to chlorantraniliprole is likely caused by mutations of the target, the ryanodine receptor, and/or mediated by an increase in detoxification enzyme activities. Although target-site resistance is documented in detail, the resistance mediated by increased metabolism has rarely been reported.RESULTSThe activity of cytochrome P450 was significantly higher in two resistant P. xylostella populations than that in a susceptible one. Among ten detected cytochrome P450 genes, CYP6BG1 was significantly overexpressed (over 80-fold) in a field-resistant population compared with expression in a susceptible one. Knockdown of CYP6BG1 by RNAi dramatically reduced the 7-ECOD activity of P450 by 45.5% and increased the toxicity of chlorantraniliprole toward P. xylostella by 26.8% at 48 h postinjection of dsRNA. By contrast, overexpression of CYP6BG1 in a transgenic Drosophila melanogaster line significantly decreased the toxicity of the insecticide to the transgenic flies.CONCLUSIONSOverexpression of CYP6BG1 may contribute to chlorantraniliprole resistance in P. xylostella. Our findings will provide new insights on understanding the mechanisms of resistance to diamide insecticides in other insect pests.
      PubDate: 2017-12-01T01:50:23.288759-05:
      DOI: 10.1002/ps.4816
  • Spinosad-mediated effects on the walking abilities, midgut, and Malpighian
           tubules of Africanized honey bee workers
    • Authors: Marcos Pereira Lopes; Kenner Morais Fernandes, Hudson Vaner Ventura Tomé, Wagner Gonzaga Gonçalves, Franciane Rosa Miranda, José Eduardo Serrão, Gustavo Ferreira Martins
      Abstract: BACKGROUNDThe global decline in Apis mellifera colonies is attributed to multiple factors, including pesticides. The bioinsecticide spinosad was initially recognized as safe for non-target organisms; however, its toxicity has been changing this concept. Here, we investigated the survival, behavioral changes, and structural changes in the midgut and Malpighian tubules of A. mellifera treated orally with a spinosad formulation.RESULTSThe field-recommended concentration of spinosad killed 100% of the bees. The concentrations (LC5 and LC50) of spinosad altered the behavioral activity, reducing the walking distance and velocity, and increasing the resting time in comparison to control. The LC50 caused disorganization of the epithelia of tested organs and induced a perceived oxidative stress and cell death.CONCLUSIONThe present work provides new insights into the debate about the role of bioinsecticides in the mortality of Africanized honey bees. Even at very low concentrations, the spinosad formulation is toxic for the vital organs midgut and Malpighian tubules and had adversely affected walking behavior. This detailed evaluation of the impact of the bioinsecticide on A. mellifera will contribute to the clarification of probable mediated disturbances caused by spinosad formulations, which can be used to develop more sustainable protocols in agriculture.
      PubDate: 2017-12-01T01:35:35.67869-05:0
      DOI: 10.1002/ps.4815
  • RNAi technology in crop protection against arthropod pests, pathogens and
    • Authors: Moises Zotti; Ericmar Avila dos Santos, Deise Cagliari, Olivier Christiaens, Clauvis Nji Tizi Taning, Guy Smagghe
      Abstract: Scientists have made significant progress to understand and unravel several aspects of dsRNA-mediated gene silencing during the last two decades. Now that the RNAi mechanism is well understood, it is time to point out some directions on how to transfer the acquired knowledge into useful applications for agriculture and crop protection. Some RNAi-based products are already available for farmers and more are expected to reach the market soon. The tailor-made dsRNA as an active ingredient for biopesticide formulations is considered a raw material that can be directed to diverse purposes, from pest control and bee protection against viruses to pesticide resistance management. The RNAi mechanism works at the mRNA level, exploiting a sequence-dependent mode of action, which makes it unique in potency and selectivity compared to conventional agrochemicals. Furthermore, the use of RNAi in crop protection can be achieved by plant-incorporated protectants through plant transformation, but also by non-transformative strategies such formulations of sprayable RNAs used as direct control agents, resistance factor repressors or developmental disruptors. In this review, RNAi is presented in an agricultural context (launched and upcoming), and we went beyond the classical presentation of successful examples of RNAi in pest-insect control and comprehensively explored its potential for the control of plant pathogens, nematodes and mites, and to fight against diseases and parasites in beneficial insects. Moreover, we also discussed its use as repressor for the management of pesticide-resistant weeds and insects. Finally, this review reports on the advances in non-transformative dsRNA delivery, the production costs of dsRNA and discusses environmental considerations.
      PubDate: 2017-11-30T06:15:30.274537-05:
      DOI: 10.1002/ps.4813
  • Metabolism of 2,4-dichlorophenoxyacetic acid contributes to resistance in
           a common waterhemp (Amaranthus tuberculatus) population
    • Authors: Marcelo R. A. Figueiredo; Lacy J. Leibhart, Zachary J. Reicher, Patrick J. Tranel, Scott J. Nissen, Philip Westra, Mark L. Bernards, Greg R. Kruger, Todd A. Gaines, Mithila Jugulam
      Abstract: BACKGROUNDSynthetic auxins such as 2,4-D have been widely used for selective control of broadleaf weeds since the mid-1940s. In 2009, an Amaranthus tuberculatus (common waterhemp) population with 10-fold resistance to 2,4-D was found in Nebraska, USA. The 2,4-D resistance mechanism was examined by conducting [14C] 2,4-D absorption, translocation and metabolism experiments.RESULTSNo differences were found in 2,4-D absorption or translocation between the resistant and susceptible A. tuberculatus. Resistant plants metabolized [14C] 2,4-D more rapidly than did susceptible plants. The half-life of [14C] 2,4-D in susceptible plants was 105 h, compared to 22 h in resistant plants. Pre-treatment with the cytochrome P450 inhibitor malathion inhibited [14C] 2,4-D metabolism in resistant plants and reduced the 2,4-D dose required for 50% growth inhibition (GR50) of resistant plants by 7-fold to 27 g ha-1, similar to the GR50 for susceptible plants in the absence of malathion.CONCLUSIONSOur results demonstrate that rapid 2,4-D metabolism is a contributing factor to resistance in A. tuberculatus, potentially mediated by cytochrome P450. Metabolism-based resistance to 2,4-D could pose a serious challenge for A. tuberculatus control due to the potential for cross-resistance to other herbicides.
      PubDate: 2017-11-30T05:55:21.525703-05:
      DOI: 10.1002/ps.4811
  • Deltamethrin is metabolized by CYP6FU1, a cytochrome P450 associated with
           pyrethroid resistance in Laodelphax striatellus
    • Authors: Mohammed Esmail Abdalla Elzaki; Mohammad Asaduzzaman Miah, Yingchuan Peng, Haomiao Zhang, Ling Jiang, Min Wu, Zhaojun Han
      Abstract: BACKGROUNDCytochrome P450s are known to play a major role in metabolizing a wide range compounds. CYP6FU1 has been over-expressed in a deltamethrin-resistant strain of Laodelphax striatellus. This study was conducted to express CYP6FU1 in Sf9 cell as a recombinant protein, to confirm its ability in metabolizing deltamethrin, chlorpyrifos, imidacloprid and traditional P450 probing substrates.RESULTSCarbon monoxide difference spectra analysis indicates that the intact CYP6FU1 protein was expressed in insect cell Sf9. Catalytic activity tests with four traditional P450 probing substrates revealed that the expressed CYP6FU1 preferentially metabolized p-nitroanisole and ethoxyresorufin, but not ethoxycoumarin and L-H EGE. The enzyme kinetic parameters were tested using p-nitroanisole. The Km and kcat values were 17.51 ± 4.29μM and Kcat 0.218 ± 0.001 per min, respectively. Furthermore, CYP6FU1 activity for degrading insecticides was tested by measuring substrate depletion and metabolite formation. The chromatogram analysis displayed obviously NADPH-dependent depletion of deltamethrin, and formation of the unknown metabolite. The molecular docking model shows that the metabolite was 4-hydroxy-deltamethrin. However, the recombinant CYP6FU1 could not metabolize imidacloprid and chlorpyrifos.CONCLUSIONThese results confirmed that the overexpressed CYP6FU1 contributes to deltamethrin resistance in L. striatellus, and p-nitroanisole might be a potential diagnostic probe for deltamethrin metabolic resistance detection and monitoring.
      PubDate: 2017-11-30T05:46:00.151064-05:
      DOI: 10.1002/ps.4808
  • Grafting on resistant interstocks reduces scion susceptibility to pear
           psylla, Cacopsylla bidens
    • Authors: Liora Shaltiel-Harpaz; Yoram Gerchman, Mwafaq Ibdah, Rike Kedoshim, Dor Rachmany, Kamel Hatib, Irit Bar-Ya'akov, Victoria Soroker, Doron Holland
      Abstract: BACKGROUNDPear psylla is a major obstacle to efficient integrated pest management in pear orchards in Israel and around the world. We used two accessions with natural resistance to pear psylla Cacopsylla bidens (Šulc) – Py.760-261 (760) and Py.701-202 (701), both apparently of Pyrus communis L. origin – as interstock grafts to confer psylla resistance to the commercially important ‘Spadona Estiva’ (Pyrus communis) scion (Spadona) cultivar. The interaction of the interstocks with quince (Cydonia oblong Mill.) and Pyrus betulifolia Bunge rootstocks was also tested.RESULTSUsage of Py.760-261 (760) and Py.701-202 (701) as interstocks for the psylla-sensitive Spadona resulted in a five-fold decrease in the C. bidens population, apparently as a consequence of antibiosis affecting nymph survival. Additionally, psylla survival was negatively correlated with the interstock length and amount of foliage. The yield and fruit quality of Spadona grafted on the ‘701’ interstock equaled or even exceeded those of the control in fruit quantity, fruit size and soluble solids content, especially on P. betulifolia rootstock.CONCLUSIONSusceptibility to pear psylla decreased significantly following grafting of commercial Spadona on resistant interstock. This is the first demonstration of increased resistance to pear psylla conferred by the use of resistant interstock in pear trees and among the few examples demonstrating transfer of resistance to insects from the interstock in fruit trees. © 2017 Society of Chemical IndustrySusceptibility to pear psylla decreased significantly following grafting of commercial Spadona on resistant interstock. This is the first demonstration of increased resistance to pear psylla conferred by the use of resistant interstock and among the few examples demonstrating transfer of resistance to insects from the interstock in fruit trees.
      PubDate: 2017-11-30T02:25:54.04662-05:0
      DOI: 10.1002/ps.4745
  • Overview of glyphosate-resistant weeds worldwide
    • Authors: Ian Heap; Stephen O Duke
      Abstract: Glyphosate is the most widely used and successful herbicide discovered to date, but its utility is now threatened by the occurrence of several glyphosate-resistant weed species. Glyphosate resistance first appeared in Lolium rigidum in an apple orchard in Australia in 1996, ironically the year that the first glyphosate-resistant crop (soybean) was introduced in the USA. Thirty-eight weed species have now evolved resistance to glyphosate, distributed across 37 countries and in 34 different crops and six non-crop situations. Although glyphosate-resistant weeds have been identified in orchards, vineyards, plantations, cereals, fallow and non-crop situations, it is the glyphosate-resistant weeds in glyphosate-resistant crop systems that dominate the area infested and growing economic impact. Glyphosate-resistant weeds present the greatest threat to sustained weed control in major agronomic crops because this herbicide is used to control weeds with resistance to herbicides with other sites of action, and no new herbicide sites of action have been introduced for over 30 years. Industry has responded by developing herbicide resistance traits in major crops that allow existing herbicides to be used in a new way. However, over reliance on these traits will result in multiple-resistance in weeds. Weed control in major crops is at a precarious point, where we must maintain the utility of the herbicides we have until we can transition to new weed management technologies. © 2017 Society of Chemical IndustryGlyphosate is the most successful herbicide discovered, but its utility is threatened by the appearance of glyphosate-resistant weed species. This article presents the current state of glyphosate-resistant weeds globally.
      PubDate: 2017-11-29T08:01:26.096334-05:
      DOI: 10.1002/ps.4760
  • Using SDS–PAGE gel fingerprinting to identify soft-bodied
           wood-boring insect larvae to species
    • Authors: Mark A O'Neill; Mia Denos, Daniel Reed
      Abstract: BACKGROUNDThis paper describes the progress that we have made in assessing the feasibility of ‘fingerprinting’ using imaged SDS–PAGE gels of haemolymph proteins, to identify soft-bodied wood-boring insect larvae such as the Asian longhorn beetle, Anoplophora glabripennis (Motscholsky, 1853) (Coleoptera: Cerambycidae). Because of stringent import restrictions and difficulty in obtaining licences to work with these organisms, we opted to work with four species of scarab beetle, Mecynorhina polyphemus (Fabricius, 1781), Pachnoda sinuata (Fabricius, 1775), Eucidella shiratica (Csiki, 1909) and Eucidella shultzeorum (Kolbe, 1906) which have near identical larval morphologies.RESULTSWe show that this technology when combined with an advanced pattern matching system (Digital Automated Identification SYstem - DAISY) can classify soft-bodied insect larvae that are almost identical morphologically to species at a level of accuracy is in excess of 98%. The study also indicates that the technology copes well with noisy data and small training sets.CONCLUSIONThe experience gained in undertaking this study gives us confidence that we will be able to develop a field deployable system in the medium term. We believe that as a high-throughput identification tool, this technology is superior to competitor technologies (e.g. fingerprinting of imaged DNA gels) in terms of speed, cost and ease of use; and therefore, is suitable for low-cost deployment in the field. © 2017 Society of Chemical IndustryThis article presents a field deployable system for the timely identification of insect pests. The technique described combines SDS-PAGE gel finger printing with advanced image recognition technology.
      PubDate: 2017-11-29T08:00:57.726246-05:
      DOI: 10.1002/ps.4766
  • First insights on insecticidal activity upon Aedes aegypti and partial
           biochemical characterization of a novel low molecular mass
           chymotrypsin-trypsin inhibitor purified from Lonchocarpus sericeus seeds
    • Authors: Luiz C P Almeida Filho; Pedro M S Tabosa, Denise C Hissa, Ilka M Vasconcelos, Ana F U Carvalho
      Abstract: BACKGROUNDArboviroses such as dengue, zika and chikungunya represent a serious issue in public health due to the absence of approved vaccine or specific antiviral drugs. One way to prevent these diseases is by combating the vector mosquito, Aedes aegypti (Diptera), which has serine proteases in the midgut. Protease inhibitors are molecules that can block enzyme activity impairing digestion and nutrition that can lead to death. Thus, we purified and characterized a novel chymotrypsin- trypsin inhibitor from Lonchocarpus sericeus (LsCTI) seeds and investigated its effect upon Ae. aegypti egg hatching, larval development and digestive proteases.RESULTSLsCTI showed a single protein band in SDS-PAGE, the molecular mass by MALDI-TOF-MS was 8,870.45 Da. Kinetics analyses revealed the noncompetitive type of inhibition and low Ki for chymotrypsin (8.24 x 10-8 M). The thermal resistance was remarkable, even at 100 °C for 180 min. The IC50 of LsCTI was 4.7 x10-7 M for Ae. aegypti midgut larvae enzymes. LsCTI did not affect egg hatchability at 0.3 mg.mL-1, but caused a high larval mortality rate (77%) and delayed development (37%).CONCLUSIONSLsCTI is a novel protease inhibitor with remarkable biochemical characteristics and a potential tool to control Ae. aegypti development.
      PubDate: 2017-11-28T23:38:03.335791-05:
      DOI: 10.1002/ps.4812
  • Inhibition of larval growth and adult fecundity in Asian Long-horned
           Beetle (Anoplophora glabripennis) exposed to azadirachtins under
           quarantine laboratory conditions
    • Authors: Dean G. Thompson; Amanda Tonon, Eduardo Beltran, Felix Hernandez
      Abstract: BACKGROUNDThe Asian Long-horned Beetle (ALB; Anoplophora glabripennis (Motschulsky)), is an invasive, wood-boring insect posing significant economic and ecological threats to the deciduous forests of North America. An efficacious and environmentally acceptable chemical control technique is a requirement of a comprehensive, integrated response strategy.RESULTSResults of this study demonstrate statistically significant, concentration-dependent effects of azadirachtins, a family of natural compounds derived from the neem tree, on both ALB larval and adult life-stages. Growth inhibitory effects on ALB larvae were greatest on early life stages. Significant effects on adults included inhibition of female feeding, oviposition effort and fecundity for adults exposed to azadirachtins via maturation feeding on systemically loaded twigs.CONCLUSIONSThese quarantine laboratory experiments verify multi-mechanistic, deleterious effects on both larval and adult life stages of ALB as an exotic, invasive insect pest of critical importance in North America. Field efficacy studies are required to further understand dose acquisition by larval and adult ALB life-stages following systemic injections to host trees under semi-operational use scenarios. Such studies could also be used to test postulates regarding optimal deployment strategies to meet objectives such as slowing the spread of this pest and protection of high value deciduous forest resources.
      PubDate: 2017-11-28T23:10:24.938679-05:
      DOI: 10.1002/ps.4810
  • Influence of no-tillage versus tillage system on common vole (Microtus
           arvalis) population density
    • Authors: Marta Heroldová; Radek Michalko, Josef Suchomel, Jan Zejda
      Abstract: BACKGROUNDWhile the ‘no-tillage’ management system generally improves soil properties and helps to control arthropod pests, it may also intensify crop infestation by the common vole (Microtus arvalis Pallas). In this study, we evaluated the impact of soil management (no-tillage, tillage), crop and previous crop (winter wheat, winter rape), and season (spring, autumn) on common vole density using data from the Common Vole Monitoring Programme undertaken by the Plant Protection Service of the Czech Republic between 2000 and 2009.RESULTSModels predicted low mean values of vole infestation across management types, crops, and seasons. The untilled fields hosted significantly more voles than the tilled fields in spring but not in autumn. More common voles were found in winter rape than in winter wheat during both seasons.CONCLUSIONRecent studies suggest that no-tillage management is more profitable than tillage management due to its positive impact on soil properties and pest control. During periods of high vole infestation, however, tillage may constitute an alternative strategy for reducing yield losses.
      PubDate: 2017-11-28T21:55:25.747337-05:
      DOI: 10.1002/ps.4809
  • Thermal plasticity potentially mediates the interaction between host Chilo
           partellus Swinhoe (Lepidoptera: Crambidae) and endoparasitoid Cotesia
           flavipes Cameron (Hymenoptera: Braconidae) under rapidly changing
    • Authors: Reyard Mutamiswa; Frank Chidawanyika, Casper Nyamukondiwa
      Abstract: BACKGROUNDIncreasing climatic average temperatures and variability elicit various insect physiological responses that affect fitness and survival and may influence subsequent trophic interactions in agroecosystems. In line with this background, we investigated short and long-term plastic responses to temperature of laboratory-reared stemborer, Chilo partellus and its larval endoparasitoid, Cotesia flavipes.RESULTSRapid cold- and -heat hardening effects in C. partellus larvae, pupae and adults and C. flavipes adults were highly significant (P ˂ 0.001). High temperature acclimation improved critical thermal limits and heat knock-down time in C. partellus larvae and C. flavipes adults respectively. However, low temperature acclimation enhanced supercooling point in C. flavipes and chill coma recovery time in both C. partellus larvae and C. flavipes adults.CONCLUSIONCurrent results suggest thermal plasticity may enhance these two species survival to lethal low and high temperatures. However, C. partellus appear more plastic compared to C. flavipes. Results have three major implications: 1) C. partellus may inhabit slightly warmer environments than C. flavipes suggesting potential mismatch in biogeography, 2) host-parasitoid relationships are complex and are likely trait dependent, and 3) host-parasitoid differential thermal plastic responses may offset biocontrol efficacy. These results may help inform biocontrol decision making under global change.
      PubDate: 2017-11-28T21:15:40.609985-05:
      DOI: 10.1002/ps.4807
  • Gene expression in response to glyphosate treatment in fleabane (Conyza
    • Authors: James P. Hereward; Jeff A. Werth, David F. Thornby, Michelle Keenan, Bhagirath Singh Chauhan, Gimme H. Walter
      Abstract: BACKGROUNDThis study takes a whole-transcriptome approach to assess gene expression changes in response to glyphosate treatment in glyphosate-resistant fleabane. We assessed gene expression changes in both susceptible and resistant lines so that the glyphosate death response could be quantified, and constitutively expressed candidate resistance genes identified. There are three copies of the glyphosate target site (5-enolpyruvylshikimate-3-phosphate; EPSPS) gene in Conyza and as Conyza bonariensis is allohexaploid there is a baseline 9 copies of the gene in any individual.RESULTSMany genes were differentially expressed in response to glyphosate treatment. Known resistance mutations are present in EPSPS2 but they are present in a glyphosate susceptible line as well as resistant lines and therefore not sufficient to confer resistance. EPSPS1 is expressed four times more than EPSPS2, further reducing the overall contribution of these mutations.CONCLUSIONWe demonstrate that glyphosate resistance in Conyza bonariensis is not the result of EPSPS mutations or overexpression, but due to a non-target-site mechanism. A large number of genes are affected by glyphosate treatment. We present a list of candidate non-target-site-resistance (NTSR) genes in fleabane for future studies into these mechanisms.
      PubDate: 2017-11-28T21:10:33.882686-05:
      DOI: 10.1002/ps.4804
  • F2 screen, inheritance and cross-resistance of field-derived Vip3A
           resistance in Spodoptera frugiperda (Lepidoptera: Noctuidae) collected
           from Louisiana, USA
    • Authors: Fei Yang; Graham P. Head, Chris Sansone, Fangneng Huang, Ryan T. Gilreath, David L. Kerns
      Abstract: BACKGROUNDFall armyworm, Spodoptera frugiperda, is a target pest of the Vip3A protein used in pyramided Bt corn and cotton in the U.S. In this study, we provide the first documentation of a resistance allele conferring Vip3A resistance in a field-derived population of S. frugiperda from U.S., and characterize its inheritance and cross-resistance.RESULTSAn F2 screen with 104 two-parent families generated from a field collection of S. frugiperda in Louisiana, U.S., resulted in one family carrying a Vip3A resistance allele. The Vip3A-resistant strain (RR) derived from the two-parent family showed a high level of resistance to Vip3A in both diet and whole plant bioassays, with a resistance ratio of>632.0-fold relative to a susceptible population (SS) based on diet-overlay bioassays. The inheritance of Vip3A resistance was monogenic, autosomal and recessive. Furthermore, the Vip3A resistance conferred no cross-resistance to Cry1F, Cry2Ab2 or Cry2Ae purified proteins, with resistance ratios of 3.5, 5.0 and 1.1, respectively.CONCLUSIONThese findings provide valuable information for characterizing Vip3A resistance, resistance monitoring, and developing effective resistance management strategies for the sustainable use of the Vip3A technology.
      PubDate: 2017-11-28T20:55:27.149433-05:
      DOI: 10.1002/ps.4805
  • Larvicidal and residual activity of imidazolium salts against Aedes
           aegypti (Diptera: Culicidae)
    • Authors: Emanuelle Goellner; Ademir Tramontini Schmitt, Júlia Lacerda Couto, Nicolas Drumm Müller, Harry Luiz Pilz Junior, Henri Stephan Schrekker, Carlos Eugenio Silva, Onilda Santos da Silva
      Abstract: BACKGROUNDAedes aegypti is an important species of mosquito, which can transmit several arboviruses such as Dengue fever, Yellow fever, Chikungunya, and Zika. As these mosquitoes are becoming resistant to most chemical insecticides used in the world, studies with new larvicides should be prioritized. Based on the known biological profile of imidazolium salts (IS), the objective of this study was to evaluate the potential of six IS as larvicides against Ae. aegypti, which was tested against Ae. aegypti larvae. The larvae mortality was measured after 24 and 48 h, and the residual larvicidal activity was also evaluated.RESULTSPromising results were obtained with aqueous solutions of the two IS 1-n-octadecyl-3-methylimidazolium chloride (C18MImCl) and 1-n-hexadecyl-3-methylimidazolium methanesulfonate (C16MImMeS), showing up to 90% mortality of larvae after exposition for 48 h. C18MImCl was more effective than C16mIMeS, causing mortality until the 15th day after larvae exposure. The application of C18MImCl that was left to dry under ambient conditions for at least two months, and dissolved in water, showed a more pronounced residual effect (36 days with 95% mortality and 80% mortality up to 78 days).CONCLUSIONThis is the first study to show the great potential of IS for the control of Ae. aegypti. Further studies are necessary to understand the mechanism of action of these compounds in the biological development of this mosquito species.
      PubDate: 2017-11-28T11:00:29.697954-05:
      DOI: 10.1002/ps.4803
  • Opportunities and challenges for harvest weed seed control in global
           cropping systems
    • Authors: Michael J. Walsh; John C. Broster, Lauren M. Schwartz-Lazaro, Jason K. Norsworthy, Adam S. Davis, Breanne D. Tidemann, Hugh J. Beckie, Drew J. Lyon, Neeta Soni, Paul Neve, Muthukumar V Bagavathiannan
      Abstract: The opportunity to target weed seeds during grain harvest was established many decades ago following the introduction of mechanical harvesting and the recognition of high weed seed retention levels at crop maturity; however, this opportunity remained largely neglected until more recently. The introduction and adoption of harvest weed seed control (HWSC) systems in Australia has been in response to widespread occurrence of herbicide-resistant weed populations. With diminishing herbicide resources and the need to maintain highly productive reduced tillage and stubble retention practices, growers began to develop systems that targeted weed seed during crop harvest. Research and development efforts over the last two decades have established the efficacy of HWSC systems in Australian cropping systems, where widespread adoption is now occurring. With similarly dramatic herbicide resistance issues now present across many of the world's cropping regions, it is timely for HWSC systems to be considered for inclusion in weed management programs in these areas. This review describes HWSC systems and establishing the potential for this approach to weed control in several cropping regions. As observed in Australia, the inclusion of HWSC systems can reduce weed populations substantially reducing the potential for weed adaptation and resistance evolution.
      PubDate: 2017-11-28T10:45:51.471508-05:
      DOI: 10.1002/ps.4802
  • The importance of trifluoromethyl pyridines in crop protection
    • Authors: Adam Burriss; Andrew J. F. Edmunds, Daniel Emery, Roger G. Hall, Olivier Jacob, Jürgen Schaetzer
      Abstract: The pyridine ring, substituted by a trifluoromethyl substituent has been successfully incorporated into molecules with useful biological properties. During the period 1990–2017 (September) fourteen crop protection products bearing a trifluoromethyl pyridine have been commercialized or proposed for an ISO common name, covering fungicides, herbicides, insecticides and nematicides. Chemical processes have been developed to provide trifluoromethyl pyridine intermediates, from non-fluorinated pyridine starting materials, at scale and with affordable costs of goods. These attractive starting materials were then readily adopted by research chemists, and elaborated through simple chemical modifications into new active ingredients. In a second approach, substituted trifluoromethyl pyridine rings have been constructed from acyclic, trifluoromethyl starting materials, which again has served to identify new active ingredients. Molecular matched pair analysis will reveal subtle, yet important differences in physico chemical and agronomic properties of trifluoromethyl pyridines compared with the phenyl analogues. This review will focus on the last 25 years, seeking to identify reasons behind the success of such research programs, and inspire the search for new crop protection chemicals containing the trifluoromethyl pyridine ring.
      PubDate: 2017-11-28T08:35:39.774258-05:
      DOI: 10.1002/ps.4806
  • Characterization of UDP-glucuronosyltransferase genes and their possible
           roles in multi-insecticide resistance in Plutella xylostella (L.)
    • Authors: Xiuxia Li; Haiyan Shi, Xiwu Gao, Pei Liang
      Abstract: BACKGROUNDUridine diphosphate-glucuronosyltransferases (UGTs), as multifunctional detoxification enzymes, play important roles in the biotransformation of various compounds. However, their roles in insecticide resistance are still unclear. This study presents a genome-wide identification of the UGTs in diamondback moth, Plutella xylostella (L.), a notorious insect pest of cruciferous crops worldwide. The possible roles of these UGTs in insecticide resistance were evaluated.RESULTSA total of 21 putative UGTs in P. xylostella were identified. Quantitative real-time polymerase chain reaction (PCR)-based analyses showed that all the UGT genes were expressed in all tested developmental stages and tissues. Bioassay results indicated that a field-collected population (BL) was resistant to 9 of 10 commonly used insecticides, and 10 of 21 UGT mRNAs were upregulated in the BL population. Exposure to the LC50 of each insecticide affected the expression of most UGT genes. Among these, the expression levels of UGT40V1, UGT45B1 and UGT33AA4 were induced by more than five insecticides, whereas indoxacarb and metaflumizone significantly repressed the expression of most UGT genes.CONCLUSIONUGTs may play important roles in the metabolism of commonly used insecticides in P. xylostella. These findings provide valuable information for further research on the physiological and toxicological functions of specific UGT genes in P. xylostella. © 2017 Society of Chemical IndustryUridine diphosphate-glucuronosyltransferases (UGTs) belong to multifunctional detoxification enzymes superfamily. This article identified 21 UGTs genes in Plutella xylostella and investigated their possible roles in multi-insecticides resistance.
      PubDate: 2017-11-28T04:33:37.842032-05:
      DOI: 10.1002/ps.4765
  • Influence of lipophilicity in O-acyl and O-alkyl derivatives of juglone
           and lawsone: a structure–activity relationship study in the search for
           natural herbicide models
    • Authors: Alexandra G Durán; Nuria Chinchilla, José MG Molinillo, Francisco A Macías
      Abstract: BACKGROUNDNaphthoquinones are known for their broad range of biological activities. Given the increasing demands of consumers in relation to food quality and growing concerns about the impact of synthetic herbicides, it is necessary to search for new agrochemicals. Natural products and allelopathy provide new alternatives for the development of pesticides with lower toxicity and greater environmental compatibility.RESULTSA structure–activity relationship to evaluate the effect of bioavailability was performed. A total of 44 O-acyl and O-alkyl derivatives of juglone and lawsone with different linear chain lengths were prepared. These compounds were tested on etiolated wheat coleoptiles, standard target species (STS) and four weeds, Echinochloa crus-galli L., Lolium rigidum Gaud., Lolium perenne L. and Avena fatua L. The results showed a strong influence of lipophilicity and, in most cases, the data fitted a logP-dependent quadratic mathematical model.CONCLUSIONThe effects produced were mostly stunting and necrosis caused by growth inhibition. The potential structure and activity behaviour is described. © 2017 Society of Chemical IndustryNew agrochemicals with lower toxicity and greater environmental compatibility are needed. Lipophilicity is a key factor of bioactive compounds. This work presents the effect of lipophilicity of different naphthoquinone derivatives with phytotoxicity evaluated.
      PubDate: 2017-11-27T08:51:22.198128-05:
      DOI: 10.1002/ps.4764
  • Resistance mechanism of Fusarium fujikuroi to phenamacril in the field
    • Authors: Yi-Ping Hou; Xiang-Pu Qu, Xue-Wei Mao, Jing Kuang, Ya-Bing Duan, Xiu-shi Song, Jian-Xin Wang, Chang-Jun Chen, Ming-Guo Zhou
      Abstract: BACKGROUNDRice bakanae disease, mainly caused by Fusarium fujikuroi, is an important disease of rice. Phenamacril has been used to control the disease for a few years in China. In 2016, nine phenamacril-resistant strains were found in the field in Zhejiang Province. The aim of the study was to clarify the mechanism of resistance of F. fujikuroi to phenamacril and the fitness of resistant strains.RESULTSThe nine F. fujikuroi strains examined were highly resistant to phenamacril. Eight of them had the point mutation TCA (Ser)  CCA (Pro) at codon 219 in the Myosin-5 protein, while the other had the point mutation TCA (Ser)  TTA (Leu) at codon 219. Myosin-5 replacement between resistant and sensitive strains confirmed that the point mutation in Myosin-5 caused the resistance of F. fujikuroi to phenamacril. Docking of phenamacril into the modeled binding pocket of Myosin-5 showed that the affinity between phenamacril and Myosin-5 decreased and a hydrogen bond could not be formed between phenamacril and the amino acid at codon 219 after it changed to Pro or Leu. There was no cross-resistance between phenamacril and other fungicides. The eight resistant strains containing the point mutation S219P had almost the same fitness as the sensitive strains, while the one resistant strain containing the point mutation S219 L showed decreased mycelial growth, sporulation and pathogenicity.CONCLUSIONIn the field, the point mutation S219P or S219 L in Myosin-5 conferred high resistance to phenamacril in F. fujikuroi. The point mutation S219P did not affect the fitness of F. fujikuroi, while the point mutation S219 L decreased its fitness. © 2017 Society of Chemical IndustryPoint mutation S219P/L in Myosin-5 conferred high resistance to phenamacril in F. fujikuroi. The point mutation S219P did not affect the fitness of F. fujikuroi while S219L decreased the fitness.
      PubDate: 2017-11-27T02:25:59.951442-05:
      DOI: 10.1002/ps.4742
  • Non-target site SDHI resistance is present as standing genetic variation
           in field populations of Zymoseptoria tritici
    • Authors: Masao Yamashita; Bart Fraaije
      Abstract: BACKGROUNDA new generation of more active succinate dehydrogenase (Sdh) inhibitors (SDHIs) is currently widely used to control Septoria leaf blotch in northwest Europe. Detailed studies were conducted on Zymoseptoria tritici field isolates with reduced sensitivity to fluopyram and isofetamid; SDHIs which have only just or not been introduced for cereal disease control, respectively.RESULTSStrong cross-resistance between fluopyram and isofetamid, but not with other SDHIs, was confirmed through sensitivity tests using laboratory mutants and field isolates with and without Sdh mutations. The sensitivity profiles of most field isolates resistant to fluopyram and isofetamid were very similar to a lab mutant carrying SdhC-A84V, but no alterations were found in SdhB, C and D. Inhibition of mitochondrial Sdh enzyme activity and control efficacy in planta for those isolates was severely impaired by fluopyram and isofetamid, but not by bixafen. Isolates with similar phenotypes were not only detected in northwest Europe but also in New Zealand before the widely use of SDHIs.CONCLUSIONThis is the first report of SDHI-specific non-target site resistance in Z. tritici. Monitoring studies show that this resistance mechanism is present and can be selected from standing genetic variation in field populations. © 2017 The
      Authors . Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.Succinate dehydrogenase inhibitors (SDHIs) are widely used for controlling Zymoseptoria tritici of wheat. This article shows resistance against SDHIs without target site mutations can be selected from standing genetic variations.
      PubDate: 2017-11-23T07:45:27.03672-05:0
      DOI: 10.1002/ps.4761
  • Measuring the effectiveness of management interventions at regional scales
           by integrating ecological monitoring and modelling
    • Authors: Robert P Freckleton; Helen L Hicks, David Comont, Laura Crook, Richard Hull, Paul Neve, Dylan Z Childs
      Abstract: BACKGROUNDBecause of site-specific effects and outcomes, it is often difficult to know whether a management strategy for the control of pests has worked or not. Population dynamics of pests are typically spatially and temporally variable. Moreover, interventions at the scale of individual fields or farms are essentially unreplicated experiments; a decrease in a target population following management cannot safely be interpreted as success because, for example, it might simply be a poor year for that species. Here, we argue that if large-scale data are available, population models can be used to measure outcomes against the prevailing mean and variance. We apply this approach to the problem of rotational management of the weed Alopecurus myosuroides.RESULTSWe derived density-structured population models for a set of fields that were not subject to rotational management (continuous winter wheat) and another group that were (rotated into spring barley to control A. myosuroides). We used these models to construct means and variances of the outcomes of management for given starting conditions, and to conduct transient growth analysis. We show that, overall, this management strategy is successful in reducing densities of weeds, albeit with considerable variance. However, we also show that one variant (rotation to spring barley along with variable sowing) shows little evidence for additional control.CONCLUSIONOur results suggest that rotational strategies can be effective in the control of this weed, but also that strategies require careful evaluation against a background of spatiotemporal variation. © 2017 The
      Authors . Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.Using large-scale data on the dynamics of weed population, local management can be benchmarked relative to the expected variance in outcomes. We apply this to the use of rotational management of resistant weeds.
      PubDate: 2017-11-23T07:25:41.739054-05:
      DOI: 10.1002/ps.4759
  • Nitrogen and water inputs to tomato plant do not trigger bottom-up effects
           on a leafminer parasitoid through host and non-host exposures
    • Authors: Yong-Cheng Dong; Peng Han, Chang-Ying Niu, Lucia Zappalà, Edwige Amiens-Desneux, Philippe Bearez, Anne-Violette Lavoir, Antonio Biondi, Nicolas Desneux
      Abstract: BACKGROUNDBottom-up and top-down forces are major components of biological control against pests in an agro-ecosystem. Understanding the multi-trophic interactions between plants and secondary consumers would help optimize pest control strategies. We manipulated nitrogen and/or water inputs to tomato plants (Solanum lycopersicum) to test whether these manipulations could trigger bottom-up effects on the parasitoid Necremnus tutae via host (Tuta absoluta) and/or non-host (Bemisia tabaci) exposures, and compared the control efficacy of N. tutae on T. absoluta in the presence and absence of B. tabaci.RESULTSThe results showed no cascading effects of plant nitrogen and/or water inputs on N. tutae via either host or non-host exposure. The bottom-up force was mitigated by chewing or sap-feeding insect consumers at the second energy level. By contrast, the top-down force on T. absoluta from parasitoids was enhanced by an additionally provided non-host, which could produce alternative food sources extending N. tutae longevity and enhancing the fitness of its offspring.CONCLUSIONOur results provided evidence for the combination of bottom-up and top-down approaches in tomato integrated pest management programs. © 2017 Society of Chemical IndustryIt's needed to recognize the basis of incorporating bottom-up and top-down forces on pest management. This article investigates the ecological consequences of stressed plants on parasitoids in a plant-herbivore-parasitoid model
      PubDate: 2017-11-22T07:20:41.478499-05:
      DOI: 10.1002/ps.4750
  • Novel use of aliphatic n-methyl ketones as a fumigant and alternative to
           methyl bromide for insect control
    • Authors: Jiwei Zhu; Anirudh Dhammi, Jaap B Kretschmar, Edward L Vargo, Charles S Apperson, R Michael Roe
      Abstract: BACKGROUNDFumigants like phosphine, methyl bromide and sulfuryl fluoride are highly effective for the control of structural, storage and agricultural arthropod pests. Unfortunately, many of these synthetic compounds are highly toxic to people, many pests have developed resistance to these compounds and methyl bromide, the ‘gold standard’ for fumigants, was de-registered because of its contribution to depletion of the stratospheric ozone layer. Alternative fumigant chemistry is needed.RESULTSSeveral plant species produce n-aliphatic methyl ketones to prevent plant herbivory. To examine the use of methyl ketones as a fumigant, structure–mortality studies were conducted using the red imported fire ant, Solenopsis invicta Buren, as a model. A new easy-to-use, inexpensive and disposable bioassay system was developed for this study. The LC50 values for heptanone, octanone, nonanone and undecanone were 4.27, 5.11, 5.26 and 8.21 µg/cm3 of ambient air, respectively. Although heptanone, octanone and nonanone were more effective than undecanone, subsequent research was conducted with 2-undecanone because this compound already has US Environmental Protection Agency (EPA) registration as a biopesticide. In dose–response field studies, 12.4 mL of undecanone injected into mounds was the lowest application rate that produced no ant activity in the mound with no re-establishment of ants. Reagent grade undecanone was more cost-effective than methyl bromide for fire ants, adult German cockroaches and tobacco budworm eggs, but slightly more expensive for adult flour beetles.CONCLUSIONThe naturally occurring methyl ketone undecanone has the potential to be an alternative to current fumigants for a variety of pest applications. © 2017 Society of Chemical IndustryCompounds 2-undecanone, 2-nonanone, 2-octanone and 2-heptanone were effective fire ant fumigants. Undecanone was shown to be effective against other insects and a potential cost-effective alternative for methyl bromide
      PubDate: 2017-11-22T07:01:07.527388-05:
      DOI: 10.1002/ps.4749
  • RNAi as an emerging approach to control Fusarium head blight disease and
           mycotoxin contamination in cereals
    • Authors: Ana Karla Machado; Neil A Brown, Martin Urban, Kostya Kanyuka, Kim E Hammond-Kosack
      Abstract: Fusarium graminearum is a major fungal pathogen of cereals worldwide, causing seedling, stem base and floral diseases, including Fusarium head blight (FHB). In addition to yield and quality losses, FHB contaminates cereal grain with mycotoxins, including deoxynivalenol, which are harmful to human, animal and ecosystem health. Currently, FHB control is only partially effective due to several intractable problems. RNA interference (RNAi) is a natural mechanism that regulates gene expression. RNAi has been exploited in the development of new genomic tools that allow the targeted silencing of genes of interest in many eukaryotes. Host-induced gene silencing (HIGS) is a transgenic technology used to silence fungal genes in planta during attempted infection and thereby reduces disease levels. HIGS relies on the host plant's ability to produce mobile small interfering RNA molecules, generated from long double-stranded RNA, which are complementary to targeted fungal genes. These molecules are transferred from the plant to invading fungi via an uncharacterised mechanism, to cause gene silencing. Here, we describe recent advances in RNAi-mediated control of plant pathogenic fungi, highlighting the key advantages and disadvantages. We then discuss the developments and implications of combining HIGS with other methods of disease control. © 2017 The
      Authors . Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.Fusarium Head Blight is a major fungal disease of cereals which contaminates the grain with harmful mycotoxins. Here we discuss the developments, advantages and concerns of RNAi for disease control.
      PubDate: 2017-11-22T02:38:02.152176-05:
      DOI: 10.1002/ps.4748
  • RNA interference of two glutathione S-transferase genes, Diaphorina citri
           DcGSTe2 and DcGSTd1, increases the susceptibility of Asian citrus psyllid
           (Hemiptera: Liviidae) to the pesticides fenpropathrin and thiamethoxam
    • Authors: Xiudao Yu; Nabil Killiny
      Abstract: BACKGROUNDThe Asian citrus psyllid, Diaphorina citri Kuwayama, is an important agricultural pest of citrus globally. Foliar application of chemical insecticides is the most widely used option for reducing D. citri populations. Knockdown of glutathione S-transferase (GST) in several insect species leads to increased susceptibility to insecticides; however, information about the detoxifying role of GST genes in D. citri is unavailable.RESULTSVia a sequence homology search, we isolated and characterized three DcGST genes (DcGSTd1, DcGSTe1 and DcGSTe2) from D. citri. Phylogenetic analysis grouped DcGSTd1 into the delta class of GST genes, whereas DcGSTe1 and DcGSTe2 were clustered in the epsilon clade. Gene expression analysis revealed that chlorpyrifos treatment increased the mRNA levels of DcGSTe1 and fenpropathrin enhanced the expression level of DcGSTd1, while DcGSTe2 was significantly up-regulated after exposure to thiamethoxam at a dose of 30% lethal concentration (LC30). RNA interference (RNAi) of DcGSTe2 and DcGSTd1 followed by an insecticide bioassay increased the mortalities of thiamethoxam-treated psyllids by 23.0% and fenpropathrin-treated psyllids by 15.0%. In contrast, knockdown of DcGSTe1 did not significantly increase the susceptibility of D. citri to any of these three insecticides. Further, feeding with double-stranded RNA (dsDcGSTe2-d1) interfusion co-silenced DcGSTe2 and DcGSTd1 expression in D. citri, and led to an increase of susceptibility to both fenpropathrin and thiamethoxam.CONCLUSIONThe findings suggest that DcGSTe2 and DcGSTd1 play unique roles in detoxification of the pesticides thiamethoxam and fenpropathrin. In addition, co-silencing by creating a well-designed dsRNA interfusion against multiple genes was a good RNAi strategy in D. citri. © 2017 Society of Chemical IndustryThe present article shows that larch extracts represent valid candidates for copper reduction in organic vineyards, and their development into a sustainable plant protection product is feasible.
      PubDate: 2017-11-22T02:35:45.898406-05:
      DOI: 10.1002/ps.4747
  • Origins and structure of chloroplastic and mitochondrial plant
           protoporphyrinogen oxidases: implications for the evolution of herbicide
    • Authors: Franck E Dayan; Abigail Barker, Patrick J Tranel
      Abstract: Protoporphyrinogen IX oxidase (PPO)-inhibiting herbicides are effective tools to control a broad spectrum of weeds, including those that have evolved resistance to glyphosate. Their utility is being threatened by the appearance of biotypes that are resistant to PPO inhibitors. While the chloroplastic PPO1 isoform is thought to be the primary target of PPO herbicides, evolved resistance mechanisms elucidated to date are associated with changes to the mitochondrial PPO2 isoform, suggesting that the importance of PPO2 has been underestimated. Our investigation of the evolutionary and structural biology of plant PPOs provides some insight into the potential reasons why PPO2 is the preferred target for evolution of resistance. The most common target-site mutation imparting resistance involved the deletion of a key glycine codon. The genetic environment that facilitates this deletion is apparently only present in the gene encoding PPO2 in a few species. Additionally, both species with this mutation (Amaranthus tuberculatus and Amaranthus palmeri) have dual targeting of PPO2 to both the chloroplast and the mitochondria, which might be a prerequisite to impart herbicide resistance. The most recent target-site mutations have substituted a key arginine residue involved in stabilizing the substrate in the catalytic domain of PPO2. This arginine is highly conserved across all plant PPOs, suggesting that its substitution could be equally likely on PPO1 and PPO2, yet it has only occurred on PPO2, underscoring the importance of this isoform for the evolution of herbicide resistance. © 2017 Society of Chemical IndustryEvolved resistance to PPO inhibitors involves mutations in the gene encoding mitochondrial PPO. Resistance to PPO inhibitors and PPO genes and enzyme structures are reviewed, and the importance of PPO2 dual targeting is considered
      PubDate: 2017-11-22T02:32:35.344223-05:
      DOI: 10.1002/ps.4744
  • Alternative control of Aedes aegypti resistant to pyrethroids: lethal and
           sublethal effects of monoterpenes bioinsecticides
    • Authors: Indira M. A. Silva; Gustavo F. Martins, Carlisson R. Melo, Alisson S. Santana, Ruan R. N. Faro, Arie F. Blank, Péricles B. Alves, Marcelo C. Picanço, Paulo F. Cristaldo, Ana Paula A. Araújo, Leandro Bacci
      Abstract: BACKGROUNDThe mosquito Aedes aegypti is intensely controlled because it is vector of viruses that cause innumerous diseases, especially in tropical regions. Due to the indiscriminate use of insecticides, populations from different regions have been resistant to pyrethroids. Here, we analyzed the lethal and sublethal effects of essential oil of Aristolochia trilobata and its major compounds on A. aegypti from susceptible and pyrethroid resistant populations.RESULTSOur results showed that the toxicity and behavioral changes to different compounds are dependent of the stage of the insect life cycle. The monoterpene ρ-cymene caused high mortality in both larvae and adult females of A. aegypti, including those from the pyrethroid resistant population. The monoterpenes limonene and linalool caused a sublethal effect in the larvae triggering changes in the swimming pattern.CONCLUSIONSThis study highlights the potential of the essential oil of A. trilobata, ρ-cymene and limonene to the control of A. aegypti and reveals the importance of analyzing the sublethal effects for the population dynamics of the A. aegypti mosquito.
      PubDate: 2017-11-21T04:55:59.99732-05:0
      DOI: 10.1002/ps.4801
  • Interactions of host-plant-resistance and seed treatments on soybean aphid
           (Aphis glycines Matsumura) and soybean cyst nematode (Heterodera glycines
    • Authors: Eric H. Clifton; Gregory L. Tylka, Aaron J. Gassmann, Erin W. Hodgson
      Abstract: BACKGROUNDSoybean cyst nematode, Heterodera glycines, and soybean aphid, Aphis glycines, are invasive, widespread and economically important pests of soybean, Glycines max, in North America. Management of these pests relies primarily on use of pesticides and soybean germplasm with genetic resistance. A three-year field study and complementary greenhouse experiment were conducted to determine the benefits of host-plant resistance (HPR) and pesticidal seed treatments for managing pest populations and preserving soybean yield.RESULTSHost-plant resistance significantly decreased the abundance of A. glycines and, in most study sites, suppressed H. glycines. Neonicotinoid seed treatment reduced A. glycines abundance on the cultivar that was susceptible to both aphids and nematodes, but abamectin nematicide seed treatment had no effect on H. glycines populations in the field or greenhouse.CONCLUSIONThese results suggest that the seed treatments included in our experiments may suppress pests, but not consistently for all soybean cultivars or study sites. Ultimately, HPR more consistently reduced pest numbers compared to the use of pesticidal seed treatments. The planting of HPR cultivars should be a primary tool for integrated pest management of both soybean pests.
      PubDate: 2017-11-21T04:35:23.084575-05:
      DOI: 10.1002/ps.4800
  • Horizontal transmission of Metarhizium anisopliae (Hypocreales:
           Clavicipitacea) and the effects of infection on oviposition rate in
           laboratory populations of Musca domestica (Diptera: Muscidae)
    • Authors: Dalton K. Baker; Steven J. Rice, Diana M. Leemon, Peter J. James
      Abstract: BACKGROUNDEffective control of house fly, Musca domestica (L.), populations currently relies on the use of chemical insecticides in most situations. Entomopathogenic fungi such as Metarhizium anisopliae (Metschn.) Sorokin may provide an alternative to chemicals and their efficacy may be enhanced by autodissemination amongst flies. This study assessed the capacity of M. anisopliae for transmission between adult M. domestica and the effects of infection on the fecundity of females.RESULTSMetarhizium anisopliae was transmitted between adult M. domestica flies with 91.67% - 100% mortality resulting across the three ratios of infected: non-infected flies tested (1:2, 1:5, 1:10). The mean lethal time (LT50) for female recipients mixed with infected male donor flies at the three ratios were 3.95, 4.79 and 5.65 days, respectively, whereas for male recipients mixed with infected female donors at the same ratios the LT50 were 4.98, 5.98 and 7.44 days, respectively. Infection with M. anisopliae significantly reduced the reproductive capacity of female flies during the first four days of infection with 25% less eggs oviposited by infected flies than those that were uninfected.CONCLUSIONAutodissemination among house flies and reduction in oviposition in the early stages of infection could contribute significantly to the effectiveness of M. anisopliae used in biocontrol programs.
      PubDate: 2017-11-21T04:21:17.799476-05:
      DOI: 10.1002/ps.4799
  • Reducing copper use in the environment: the use of larixol and larixyl
           acetate to treat downy mildew caused by Plasmopara viticola in viticulture
    • Authors: Barbara Thuerig; Emily E James, Hans-Jakob Schärer, Moses K Langat, Dulcie A Mulholland, Jonas Treutwein, Ina Kleeberg, Mathias Ludwig, Praveen Jayarajah, Oscar Giovannini, Emilia Markellou, Lucius Tamm
      Abstract: BACKGROUNDPlant extracts might provide sustainable alternatives to copper fungicides, which are still widely used despite their unfavourable ecotoxicological profile. Larch bark extract and its constituents, larixyl acetate and larixol, have been shown to be effective against grapevine downy mildew (Plasmopara viticola) under semi-controlled conditions. The aim of this study was to reduce the gap between innovation and the registration of a marketable product, namely to develop scalable extraction processes and to evaluate and optimise the performance of larch extracts under different conditions.RESULTSToxicologically and technically acceptable solvents like ethanol were used to extract the active compounds larixyl acetate and larixol from bark in sufficient amounts and their combined concentration could be increased by up to 39% by purification steps. The combined concentration of larixyl acetate and larixol from larch turpentine could be increased by up to 66%. The Minimal Inhibitory Concentration (MIC100) against P. viticola in vitro (6-23 µg mL-1) and the Effective Concentration (EC50) in planta under semi-controlled conditions (0.2-0.4 mg mL-1) were promising compared with other plant extracts. In vineyards, efficacies of larch extracts reached up to 68% in a stand-alone strategy and 84% in low-copper strategies.CONCLUSIONLarch extracts represent valid candidates for copper reduction in organic vineyards, and their development into a sustainable plant protection product might be feasible. © 2017 Society of Chemical IndustryThe present article shows that larch extracts represent valid candidates for copper reduction in organic vineyards, and their development into a sustainable plant protection product is feasible.
      PubDate: 2017-11-21T02:55:37.488429-05:
      DOI: 10.1002/ps.4733
  • Novel CYP6D1 and voltage gated sodium channel alleles of the house fly
           (Musca domestica) and their roles in pyrethroid resistance
    • Authors: Jing Pan; Chan Yang, Yan Liu, Qi Gao, Mei Li, Xinghui Qiu
      Abstract: BACKGROUNDThe house fly Musca domestica is an important disease vector. Point mutation mediated target-site insensitivity of the voltage gated sodium channel (VSSC) and increased detoxification mediated by CYP6D1 overexpression have been characterized to be two major mechanisms of pyrethroid resistance. In this study, genetic mutations in Vssc and CYP6D1 genes and their contribution to pyrethroid resistance were investigated.RESULTSTwelve lines of house flies homozygous for four genotypes were established. House flies carrying 1014F mutation and over-expressing CYP6D1 had higher resistance to pyrethroids than those carrying 1014F alone. The presence of the 15bp insert in the promoter region of CYP6D1 gene did not necessarily result in a significant increase of CYP6D1 mRNA and pyrethroid resistance level. A novel Vssc allele carrying two mutations (G1924D and G2004S) in combination with the classic 1014F and a novel CYP6D1 allele that is very similar to CYP6D1v1 were identified in Chinese house flies.CONCLUSIONThis work demonstrates the effect of genetic mutations in CYP6D1 and Vssc on the susceptibility of house flies to pyrethroids, and verifies that 15bp insert-containing CYP6D1 alleles have a single origin. These findings offer insights into the evolution of insecticide resistance and have implication for house fly control.
      PubDate: 2017-11-20T11:05:20.936227-05:
      DOI: 10.1002/ps.4798
  • Priming of cowpea volatile emissions with defense inducers enhances the
           plant's attractiveness to parasitoids when attacked by caterpillars
    • Authors: Islam S. Sobhy; Toby J. A. Bruce, Ted C. J. Turlings
      Abstract: BACKGROUNDThe manipulation of herbivore-induced volatile organic compounds (HI-VOCs) via the application of the inducers BTH [benzo (1,2,3) thiadiazole-7-carbothioic acid S-methyl ester] and Laminarin [β-1,3-glucan] is known to enhance the attractiveness of caterpillar-damaged cotton and maize plants to parasitoids. To test if this is also the case for legumes, we treated cowpea with these inducers and studied the effects on HI-VOC emissions and the attraction of three generalist endoparasitoids.RESULTSAfter applying the inducers and subjecting the plants to either real or mimicked herbivory by Spodoptera littoralis caterpillars, females of the parasitoids Campoletis sonorensis and Microplitis rufiventris showed a strong preference for BTH treated plants, whereas Cotesia marginiventris females were strongly attracted to both BTH and Laminarin treated plants with real or mimicked herbivory. Treated plants emitted more of certain HI-VOCs, but considerably less indole, linalool and several sesquiterpenes. Multivariate data analysis revealed that enhanced wasp attraction after treatment was correlated with high relative concentrations of nonanal, α-pinene, (E)-β-ocimene and DMNT, and with low relative concentrations of indole, (S)-linalool and (E)-β-farnesene. Inducer treatments had no significant effect on leaf consumption by the caterpillars.CONCLUSIONOur findings confirm that treating cowpea plants with inducers can enhance their attractiveness to biological control agents.
      PubDate: 2017-11-20T10:40:23.762919-05:
      DOI: 10.1002/ps.4796
  • Advantages of diapause in Trichogramma dendrolimi mass production via eggs
           of the Chinese silkworm, Antheraea pernyi
    • Authors: Jun-Jie Zhang; Xue Zhang, Lian-Sheng Zang, Wen-Mei Du, Yang-Yang Hou, Chang-Chun Ruan, Nicolas Desneux
      Abstract: BACKGROUNDTrichogramma dendrolimi Matsumura is widely used as biological control agent for lepidopteran agricultural pests control in China and can be successfully reared using the large eggs of the Chinese silkworm, Antheraea pernyi. In this study, biological parameters of diapaused, non-diapaused, and cold-stored T. dendrolimi were investigated for two generations on host eggs of A. pernyi under the laboratory conditions.RESULTSThe cold-stored T. dendrolimi performed poorer than diapaused and non-diapaused T. dendrolimi based on biological parameters. For F1 generation, the non-diapaused T. dendrolimi had higher emergence rate, longer longevity, and lower deformed proportion than diapaused T. dendrolimi. For F2 generation, the diapaused T. dendrolimi had lower proportion of unemerged parasitoids than those of non-diapaused. However, the diapaused T. dendrolimi had higher number of parasitized hosts than those of non-diapaused in both generations. For F1 generation, similar index of population trend (I) for diapaused (140.792) and non-diapaused (141.542) T. dendrolimi was found and it was approximately 3.4 times than that of cold-stored T. dendrolimi (41.698). For F2 generation, the diapaused T. dendrolimi showed the largest I (146.791), followed by non-diapaused (136.859) and cold-stored T. dendrolimi (59.607).CONCLUSIONIn a three-year augmentative field release from 2014 to 2016, diapaused Trichogramma showed effective parasitism on eggs of the Asian corn borer, Ostrinia furnacalis. These results indicated that diapaused T. dendrolimi can be an efficient and alternative method for mass rearing of T. dendrolimi for long-term cold storage.
      PubDate: 2017-11-20T10:35:29.652235-05:
      DOI: 10.1002/ps.4795
  • Discovery of Vg and VgR gene expression profiles related to host-plant
           suitability of Spodoptera exigua
    • Authors: Jing Zhao; Yang Sun, Liubin Xiao, Yongan Tan, Yiping Jiang, Lixin Bai
      Abstract: BACKGROUNDSpodoptera exigua, a worldwide phytophagous pest, causes considerable economic agricultural losses. Understanding the relationship between its fecundity and host plant is a basic and important component of early forecasting of beet armyworm. However, little is known about the molecular mechanism by which distinct hosts affect S. exigua fecundity.RESULTSIn this study, the key parameters of S. exigua grown on distinct hosts were investigated; host plants could be ranked as lettuce>shallot> tomato> celery in their order of suitability. Full-length SEVgR cDNA was cloned, with sex-, stage- and tissue-specific expression characteristics assessed. SEVg/SEVgR levels were markedly modulated by host nutrients (P
      PubDate: 2017-11-17T08:40:23.758459-05:
      DOI: 10.1002/ps.4794
  • Monitoring resistance of Cydia pomonella (L.) Spanish field populations to
           new chemical insecticides and the mechanisms involved
    • Authors: Dolors Bosch; Marcela A Rodríguez, Jesús Avilla
      Abstract: BACKGROUNDA widespread resistance of Cydia pomonella to organophosphates was demonstrated in populations from the Spanish Ebro Valley area that showed high levels of enzymatic detoxification. To determine the efficacy of new insecticides, neonate larvae bioassays were carried out on twenty field codling moth populations collected from three different Spanish apple production areas. Synergist bioassays were performed to detect the enzymatic mechanisms involved.RESULTSThe least active ingredients were methoxyfenozide, with 100% of the populations showing significantly lower mortality than the susceptible strain, and lambda-cyhalothrin, with very high resistant ratios (872.0 for the most resistant field population). Approximately 50% of the populations were resistant or tolerant to thiacloprid. By contrast, tebufenozide was very effective in all the field populations, as was chlorpyrifos-ethyl despite its widespread use during the last few years. Indoxacarb, spinosad and chlorantraniliprole also provided high efficacy, as did emamectin and spinetoram, which are not yet registered in Spain.CONCLUSIONThe resistant Spanish codling moth populations can be controlled using new reduced-risk insecticides. The use of synergists showed the importance of the concentration applied and the difficulty of interpreting the results in field populations that show multiple resistance to different active ingredients.
      PubDate: 2017-11-16T23:20:32.719938-05:
      DOI: 10.1002/ps.4791
  • Seasonal variation in effectiveness of the boar-operated system to deliver
           baits to wild boar
    • Authors: Francesco Ferretti; Julia Coats, Dave P Cowan, Stéphane Pietravalle, Giovanna Massei
      Abstract: BACKGROUNDWild boar and feral pig numbers are growing worldwide and have substantial economic and environmental impacts. Bait-delivered pharmaceuticals such as disease vaccines, toxicants and contraceptives are advocated to mitigate these impacts. Effective campaigns based on these pharmaceuticals rely on optimising the target species' bait uptake, which may differ between seasons. We investigated seasonal differences in the use of Boar-Operated Systems (BOSs) by wild boar and non-target species in an English woodland.RESULTSIn a pre-trial phase (BOS left open), wild boar, wild mammals, birds, livestock and companion animals fed on the peanuts and maize used as bait in the BOS. During the trial (BOS closed), only wild boar consumed the baits. Wild boar visited and fed from a larger number of BOSs in spring than in summer or winter. No aggressive intra-group interactions were recorded when wild boar fed from the BOSs but adult males were observed to monopolise two BOSs. Group size was highest in spring and bait uptake was lowest in winter.CONCLUSIONThe study confirmed the species-specificity of the BOS throughout the year and highlighted that, at least in this area, bait uptake by wild boar for baits delivered through the BOS would be maximised in spring. © 2017 Crown copyright. Pest Management Science © 2017 Society of Chemical Industry
      PubDate: 2017-11-16T03:20:33.944312-05:
      DOI: 10.1002/ps.4723
  • Effects of seasonal changes in cotton plants on the evolution of
           resistance to pyramided cotton producing the Bt toxins Cry1Ac and Cry1F in
           Helicoverpa zea
    • Authors: Yves Carrière; Ben A Degain, Gopalan C Unnithan, Virginia S Harpold, Shannon Heuberger, Xianchun Li, Bruce E Tabashnik
      Abstract: BACKGROUNDIn pests with inherently low susceptibility to Bacillus thuringiensis (Bt) toxins, seasonal declines in the concentration of Bt toxins in transgenic crops could accelerate evolution of resistance by increasing the dominance of resistance. Here, we evaluated Helicoverpa zea survival on young and old cotton plants that produced the Bt toxins Cry1Ac and Cry1F or did not produce Bt toxins.RESULTSUsing a strain selected for resistance to Cry1Ac in the laboratory, its parent strain that was not selected in the laboratory, and their F1 progeny, we showed that resistance to Cry1Ac + Cry1F cotton was partially dominant on young and old plants. On Cry1Ac + Cry1F cotton, redundant killing was incomplete on young plants but nearly complete on old plants. No significant fitness costs on non-Bt cotton occurred on young plants, but large recessive costs affected survival on old plants. Simulation models incorporating the empirical data showed that the seasonal changes in fitness could delay resistance to Cry1Ac + Cry1F cotton by inducing low equilibrium frequencies of resistance alleles when refuges are sufficiently large.CONCLUSIONOur results suggest that including effects of seasonal changes in fitness of pests on Bt crops and refuge plants can enhance resistance risk assessment and resistance management. © 2017 Society of Chemical Industry
      PubDate: 2017-11-15T07:45:26.427132-05:
      DOI: 10.1002/ps.4746
  • Genetically engineering better fungal biopesticides
    • Authors: Brian Lovett; Raymond John St. Leger
      Abstract: Microbial insect pathogens offer an alternative means of pest control with the potential to wean us off our heavy reliance on chemical pesticides. Insect pathogenic fungi play an important natural role in controlling disease vectors and agricultural pests. Most commercial products employ Ascomycetes in the genera Metarhizium and Beauveria. However, their utilization has been limited by inconsistent field results as a consequence of sensitivity to abiotic stresses and naturally low virulence. Other naturally occurring biocontrol agents also face these hurdles to successful application, but the availability of complete genomes and recombinant DNA technologies have facilitated design of multiple fungal pathogens with enhanced virulence and stress resistance. Many natural and synthetic genes have been inserted into entomopathogen genomes. Some of the biggest gains in virulence have been obtained using genes encoding neurotoxic peptides, peptides that manipulate host physiology and proteases and chitinases that degrade the insect cuticle. Prokaryotes, particularly extremophiles, are useful sources of genes for improving entomopathogen resistance to ultraviolet (UV) radiation. These biological insecticides are environmentally friendly and cost-effective insect pest control options. © 2017 Society of Chemical Industry
      PubDate: 2017-11-14T06:05:32.165531-05:
      DOI: 10.1002/ps.4734
  • Characterization of the mechanism of action of the fungicide fenpicoxamid
           and its metabolite UK-2A
    • Authors: David H Young; Nick X Wang, Stacy T Meyer, Cruz Avila-Adame
      Abstract: BACKGROUNDFenpicoxamid is a new fungicide for control of Zymoseptoria tritici, and is a derivative of the natural product UK-2A. Its mode of action and target site interactions have been investigated.RESULTSUK-2A strongly inhibited cytochrome c reductase, whereas fenpicoxamid was much less active, consistent with UK-2A being the fungicidally active species generated from fenpicoxamid by metabolism. Both compounds caused rapid loss of mitochondrial membrane potential in Z. tritici spores. In Saccharomyces cerevisiae, amino acid substitutions N31K, G37C and L198F at the Qi quinone binding site of cytochrome b reduced sensitivity to fenpicoxamid, UK-2A and antimycin A. Activity of fenpicoxamid was not reduced by the G143A exchange responsible for strobilurin resistance. A docking pose for UK-2A at the Qi site overlaid that of antimycin A. Activity towards Botrytis cinerea was potentiated by salicylhydroxamic acid, showing an ability of alternative respiration to mitigate activity. Fungitoxicity assays against Z. tritici field isolates showed no cross-resistance to strobilurin, azole or benzimidazole fungicides.CONCLUSIONFenpicoxamid is a Qi inhibitor fungicide that provides a new mode of action for Z. tritici control. Mutational and modeling studies suggest that the active species UK-2A binds at the Qi site in a similar, but not identical, fashion to antimycin A. © 2017 The
      Authors . Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
      PubDate: 2017-11-14T03:10:37.159934-05:
      DOI: 10.1002/ps.4743
  • Monitoring of Sesamia nonagrioides resistance to MON 810 maize in the
           European Union: lessons from a long-term harmonized plan
    • Authors: Gema P Farinós; Pedro Hernández-Crespo, Félix Ortego, Pedro Castañera
      Abstract: BACKGROUNDUse of MON 810 maize (Zea mays), which expresses the insecticidal protein Cry1Ab from Bacillus thuringiensis (Bt maize), is a highly effective method to control Sesamia nonagrioides (Lefèbvre), a key maize pest in Mediterranean countries. Monitoring programs to assess the potential development of resistance of target pests to Bt maize are mandatory in the European Union (EU). Here we report the results of the S. nonagrioides resistance monitoring plan implemented for MON 810 maize in the EU between 2004 and 2015 and reassess the different components of this long-term harmonized plan.RESULTSNo major shifts in the susceptibility of S. nonagrioides to the Cry1Ab protein have occurred over time. The reassessment of this long-term program has identified some practical and technical constraints, allowing us to provide specific recommendations for improvement: use reference strains instead of susceptibility baselines as comparators for field-collected populations; shift from dose–response bioassays to diagnostic concentrations; and focus monitoring on areas with high adoption rates, such as the Ebro basin in Spain.CONCLUSIONThere are no signs of field resistance of S. nonagrioides to the Cry1Ab protein of MON 810 maize. Specific recommendations for improvement are provided, based on the knowledge and experience accumulated through the implementation of this unique EU-wide harmonized plan. © 2017 Society of Chemical Industry
      PubDate: 2017-11-13T04:25:44.659945-05:
      DOI: 10.1002/ps.4735
  • Lowering treatment temperature reduces salmon mortality: a new way to
           treat with hydrogen peroxide in aquaculture
    • Authors: Kathy Overton; Francisca Samsing, Frode Oppedal, Lars H Stien, Tim Dempster
      Abstract: BACKGROUNDHydrogen peroxide (H2O2) baths are widely used to reduce numbers of salmon lice on farmed Atlantic salmon. Fish mortalities often occur after baths, with warmer temperatures increasing lethality. We tested whether mortality could be reduced and lice removal efficacy maintained by lowering bath temperatures relative to ambient temperatures. Post-smolt salmon infected with lice were held at 10, 13 or 16 °C, and treated with 1.5 g/L H2O2 for 20 min at equal or lower bath temperatures of 7, 10 or 13 °C.RESULTSSalmon mortality decreased as ambient and bath temperatures decreased. No mortality occurred when fish at 13 °C were treated at 7 °C. For ambient temperatures of 16 °C, the number of lice remaining was reduced by four-fold when treated at 7 °C compared with 13 °C. All treatments in which mortality was zero had similar efficacies regardless of bath temperature.CONCLUSIONWe took salmon from warmer to colder temperatures to determine the optimum bathing temperature to prevent mortality. A temperature of 7 °C was optimal when treating with 1.5 g/L of H2O2, as mortality was zero and pre-adult lice removal was unchanged. By manipulating temperature, we developed a new method of H2O2 bathing that reduces mortality. When ambient temperatures are>10 °C, we recommend that the industry decrease H2O2 bath temperatures. © 2017 Society of Chemical Industry
      PubDate: 2017-11-13T03:54:57.404207-05:
      DOI: 10.1002/ps.4751
  • Behavioral responses of pest mole crickets, Neoscapteriscus spp.
           (Orthoptera: Gryllotalpidae), to selected insecticides
    • Authors: Olga S Kostromytska; Michael E Scharf, Eileen A Buss
      Abstract: BACKGROUNDMole crickets (Neoscapteriscus spp.) consume turfgrasses and pasture grasses and uproot plants by their tunneling, which is detrimental to turf aesthetics and decreases forage quantity and quality. Insecticides are frequently used to prevent damage. In typical field trials, damage symptoms, not percent mortality or achieved level of control, are used to assess treatment efficacy. Here, however, laboratory tests assessed the direct effect of key insecticides on Neoscapteriscus mole cricket behavior.RESULTSMole crickets, Neoscapteriscus spp., were able to detect and avoid areas treated with fipronil [formulated product (FP)] and imidacloprid (FP). They tunneled less in sand treated with fipronil and avoided sand treated with fipronil and imidacloprid if given a choice. Mole crickets escaped areas treated with acephate, bifenthrin and fipronil. Bifenthrin and acephate caused increased tunneling during the first 90 min of observation. Fipronil and imidacloprid significantly reduced overall tunneling on treated areas.CONCLUSIONTested insecticides elicited two types of behavioral changes in Neoscapteriscus mole crickets: increased locomotory activity and tunneling [acephate (organophosphate) and bifenthrin (pyrethroid)] and reduced spatial movement [fipronil (phenylpyrazole) and imidacloprid (neonicotinoid)]. These behavioral responses resulted mainly from contact chemoreception and inherent neurotoxicity of the chemicals on Neoscapteriscus mole crickets. © 2017 Society of Chemical Industry
      PubDate: 2017-11-11T09:55:28.477892-05:
      DOI: 10.1002/ps.4732
  • Plant protection means used in organic farming throughout the European
    • Authors: Ewa Matyjaszczyk
      Abstract: Following the obligatory implementation of Integrated Pest Management in the European Union, the plant protection means suitable for application in organic agriculture attracted the attention of quite a wide group of potential users. In spite of the common rules of organic production, as well as the uniform principles of placing plant protection products on the market, the availability of products that can be legally used in organic crop protection differs significantly among the Member States.There is a uniform list of 10 basic substances that can be used in the protection of organic crops throughout the entire EU. Twelve Member States have official registers of plant protection products for use in organic agriculture, and the total number of qualified products per country varies from 11 in Lithuania to 576 in Italy. Some products that improve plant vigour or resistance and may be of use in protection of organic crops are placed on the market as biostimulants. They fall under the law that governs fertilisers and the systems of their registration vary widely among the Member States. In addition, there exists a number of products that have been legally introduced onto the market of some Member States without registration due to a loophole in the law. The use of unregistered products in organic agriculture raises some doubts, but currently it seems that there is no legal basis on which to explicitly prohibit the practice.
      PubDate: 2017-11-10T04:30:20.256462-05:
      DOI: 10.1002/ps.4789
  • High carbon dioxide concentration and elevated temperature impact the
           growth of weeds but do not change the efficacy of glyphosate
    • Authors: Khawar Jabran; Mehmed Nedim Doğan
      Abstract: BACKGROUNDGlobal climate changes may impact the growth and management of weed species. This work was aimed at evaluating the impact of recent climate changes on growth of weeds and herbicide efficacy. The effects of temperature, carbon dioxide (CO2), and herbicide on growth and control of Bromus tectorum L., Hordeum murinum L., and Lactuca serriola L. were studied. Treatments included: 1) Control or ambient environment (CO2=400-450 ppm; temperature 20/10 °C day/night); 2) Elevated temperature (CO2=400-450 ppm; temperature 25/15 °C day/night); 3) High CO2 and elevated temperature (CO2=800-900 ppm; temperature 25/15 °C day/night); 4) High CO2 (CO2=800-900 ppm; temperature 20/10 °C day/night).RESULTSHigh CO2-concentration and high CO2-concentration plus high temperature improved the biomass and growth parameters of weeds in the studies. In general, high temperature had either a neutral, negative or slightly positive effect on the growth of weed species. Climatic conditions did not affect the activity of glyphosate; its application provided equal and effective weed control under either of the CO2 or temperature levels or their combinations.CONCLUSIONSPositive effect of high CO2-concentration on growth of weeds does not impact the activity of glyphosate.
      PubDate: 2017-11-09T05:10:22.193299-05:
      DOI: 10.1002/ps.4788
  • Coarse and nano emulsions for effective delivery of natural pest control
           agent pulegone for stored grain protection
    • Authors: Gilad Golden; Elazar Quinn, Eli Shaaya, Moshe Kostyukovsky, Elena Poverenov
      Abstract: BACKGROUNDOne of the most significant contributors to the global food crisis is grain loss during storage mainly caused by pest insects. Currently, there are two main methods used for insect pest control: fumigation and grain protection by contact insecticides. Since some chemical insecticides can harm humans and environment, there is a global tendency to reduce their use by finding alternative eco-friendly approaches.RESULTSIn this paper, a natural pest-managing agent pulegone was encapsulated into coarse and nano emulsions. The emulsions were characterized by spectroscopic and microscopic methods and their stability and pulegone release ability were examined. The insecticidal activity of the prepared formulations against two stored product insects, rice weevil (Sitophilus oryzae L.) and red flour beetle (Tribolium castaneum Herbst) was demonstrated. The nano emulsion-based formulation offered significant advantages and provided powerful bioactivity, with high (> 90%) mortality rates for as long as 5 weeks for both insects, in comparison with coarse emulsions showing high efficacy for only one week.CONCLUSIONThe developed pulegone-based nano emulsions could serve as a model for an effective alternative method for pest control. Though being of a natural source, toxicological studies should be done before the widespread application of pulegone or pulegone-containing essential oils on dry food products.
      PubDate: 2017-11-09T04:00:41.980471-05:
      DOI: 10.1002/ps.4787
  • The interactions between gut microbiota and entomopathogenic fungi: a
           potential approach for biological control of Blattella germanica (L.)
    • Authors: Fan Zhang; Xiao X Sun, Xian C Zhang, Shuo Zhang, Jie Lu, Yong M Xia, Yan H Huang, Xue J Wang
      Abstract: BACKGROUNDMetarhizium anisopliae and Beauveria bassiana mainly infect insects through the cuticle; gut infection occasionally occurs. Micro-organisms existing in the gut may play a crucial role in the evolution and ecology of host defenses against fungal pathogens. To evaluate whether the gut bacteria participate in antifungal activity, and to determine their role in host protection, the interactions between gut bacteria and M. anisopliae and the diversity of gut microbiota in cockroaches were studied.RESULTSAn oral feeding test showed that the mortality of conventional cockroaches was significantly lower than that of germ-free cockroaches; both gut homogenates and aqueous fecal extracts showed antifungal activity, but the samples from germ-free cockroaches did not. Twenty-two bacterial strains with antifungal activity and siderophore-producing ability were isolated from the gut and feces of cockroaches. Using high-throughput sequencing techniques, a total of 23 different phyla and 212 genera were detected. The composition of the microbiota of the hindgut was vastly different from those of the foregut and midgut; higher diversity and abundance of Bacteroides and Pseudomonas were found in the hindgut.CONCLUSIONThe gut microbiota of German cockroaches may play a critical role in protecting cockroaches from fungal invasion and colonization. Removing certain bacteria from the B. germanica microbiota may facilitate microbial control using fungal pathogens. © 2017 Society of Chemical Industry
      PubDate: 2017-11-09T03:56:37.49644-05:0
      DOI: 10.1002/ps.4726
  • Tembotrione detoxification in HPPD-inhibitor resistant Palmer amaranth
           (Amaranthus palmeri S. Wats.)
    • Authors: Anita Küpper; Falco Peter, Peter Zöllner, Lothar Lorentz, Patrick J. Tranel, Roland Beffa, Todd A. Gaines
      Abstract: BACKGROUNDResistance to the 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide tembotrione in an Amaranthus palmeri population from Nebraska (NER) has previously been confirmed to be due to enhanced metabolism. The objective of this study was to identify and quantify the metabolites formed in susceptible (NES) and NER biotypes.RESULTSNER and NES formed the same metabolites. Tembotrione metabolism in NER differed from NES in that resistant plants showed faster 4-hydroxylation followed by glycosylation. The T50 value (time for 50% production of the maximum 4-hydroxylation product) was 4.9 and 11.9 h for NER and NES, respectively. This process is typically catalyzed by cytochrome P450 enzymes. Metabolism differences between NER and NES were most prominent under 28°C conditions and herbicide application at the four-leaf stage.CONCLUSIONFurther research on identifying the gene or genes responsible for conferring metabolic resistance to HPPD-inhibitors should focus on cytochrome P450s. Such research is important because non-target-site based resistance (NTSR) poses the threat of cross resistance to other chemical classes of HPPD-inhibitors, other herbicide modes of action, or even unknown herbicides.
      PubDate: 2017-11-03T04:51:13.848614-05:
      DOI: 10.1002/ps.4786
  • Tropical wood resistance to the West Indian drywood termite Cryptotermes
           brevis: If termites can't chew…
    • Authors: Lírio Cosme; Marcelo M Haro, Nelsa Maria P Guedes, Terezinha Maria C Della Lucia, Raul Narciso C Guedes
      Abstract: BACKGROUNDThe importance and impact of invasive species are usually considered based on their economic implications, particularly their direct damage. The West Indian drywood termite Cryptotermes brevis (Walker) is an example and concern in structural lumber, furniture, and other wood products. Despite its importance, its tropical wood preferences and wood physical characteristics contributing to resistance were not yet investigated. Here we developed wood testing units to allow the X-ray recording of termite colonization and then subsequently tested tropical wood resistance to the termite through free-choice and no-choice bioassays using these wood testing units. The relevance of wood density and hardness as determinants of such resistance was also tested, as was the termite mandible wear.RESULTSThe wood testing units used allowed the assessment of the termite infestation and wood area loss allowing subsequent choice bioassays. While pine (Pinus sp.), jequitiba (Cariniana sp.) and angelim (Hymenolobium petraenum) exhibited heavier losses and higher infestations, the opposite took place with cumaru (Dipteryx odorata), guariuba (Clarisia racemosa), and purpleheart (Peltogyne sp.); courbaril (Hymenaea courbaril), eucalyptus (Eucalyptus sp.), and tatajuba (Bagassa guianensis) exhibited intermediary results.CONCLUSIONWood hardness and mainly wood density were key determinants of wood resistance to the termites, which exhibited lower infestations associated with greater mandible wear when infesting harder high-density wood.
      PubDate: 2017-11-02T10:20:24.843125-05:
      DOI: 10.1002/ps.4785
  • Stability of strigolactone analog GR24 toward nucleophiles
    • Authors: Rostislav Halouzka; Petr Tarkowski, Binne Zwanenburg, Sanja Ćavar Zeljković
      Abstract: BACKGROUNDStrigolactones (SLs) are plant hormones that play various roles in plant development. The chemical stability of SLs depends on the solvent, pH, and the presence of nucleophiles. Hydrolysis leads to detachment of the butenolide ring, and plays a crucial role in the initial stages of the signal-transduction process occurring between the receptor and the SL signaling molecule.RESULTSTo date, two different mechanisms have been proposed for SL hydrolysis. Results obtained from kinetic, thermodynamic, and mass spectral data of the reaction between widely used synthetic strigolactone analog GR24 and seven different nucleophiles, demonstrate that the reaction proceeds via the Michael addition-elimination mechanism.CONCLUSIONSThis paper provides valuable information on the chemical stability of GR24 in different plant growing media and buffers. Such information is valuable for scientists using GR24 treatments to study SL-regulated processes in plants.
      PubDate: 2017-11-02T09:50:25.976691-05:
      DOI: 10.1002/ps.4782
  • Distribution of glyphosate-resistant Amaranthus spp. in Nebraska
    • Authors: Bruno C. Vieira; Spencer L. Samuelson, Guilherme S. Alves, Todd A Gaines, Rodrigo Werle, Greg R. Kruger
      Abstract: BACKGROUNDPalmer amaranth (Amaranthus palmeri S. Wats.), common waterhemp (Amaranthus tuberculatus var. rudis), and redroot pigweed (Amaranthus retroflexus L.) are major weeds occurring in fields throughout Nebraska with recurrent grower complaints regarding control with glyphosate. The objective of this study was to investigate the frequency and distribution of glyphosate-resistant Palmer amaranth, common waterhemp, and redroot pigweed populations in Nebraska. The study also aimed to investigate how agronomic practices influence the occurrence of glyphosate resistance in the three Amaranthus species.RESULTSGlyphosate resistance is widespread in common waterhemp (81% of the screened populations), few Palmer amaranth populations were glyphosate-resistant (6% of the screened populations), whereas no glyphosate-resistant redroot pigweed populations were identified in Nebraska. Weed species, geographic region within the state, and current crop were the most important factors predicting the occurrence of glyphosate resistance in fields infested with Amaranthus species in Nebraska.CONCLUSIONThe intensive glyphosate selection pressure exerted in soybean fields in eastern Nebraska is one of the major factors causing widespread occurrence of glyphosate resistance in common waterhemp in the state. The relatively low frequency of glyphosate-resistant Palmer amaranth in the state highlights the importance of the application timing and the adoption of multiple modes of action in weed management practices to delay the evolution of glyphosate resistance.
      PubDate: 2017-11-02T09:35:24.805049-05:
      DOI: 10.1002/ps.4781
  • The implications of spatially variable pre-emergence herbicide efficacy
           for weed management
    • Authors: Helen Metcalfe; Alice E Milne, Richard Hull, Alistair J Murdoch, Jonathan Storkey
      Abstract: BACKGROUNDThe efficacy of pre-emergence herbicides within fields is spatially variable due to soil heterogeneity. We quantified the effect of soil organic matter on the efficacy of two pre-emergence herbicides; flufenacet and pendimethalin, against A. myosuroides and investigated the implications of variation in organic matter for weed management using a crop-weed competition model.RESULTSSoil organic matter played a critical role in determining the level of control achieved. The high organic matter soil had more surviving weeds with higher biomass than the low organic matter soil. In the absence of competition, surviving plants recovered to produce the same amount of seed as if no herbicide were applied. The competition model predicted that weeds surviving pre-emergence herbicides could compensate for sub-lethal effects even when competing with the crop. The ED50 was higher for weed seed production than seedling mortality or biomass. This difference was greatest on high organic matter soil.CONCLUSIONThese results show that the application rate of herbicides should be adjusted to account for within-field variation in soil organic matter. The results from the modelling emphasised the importance of crop competition in limiting the capacity of weeds surviving pre-emergence herbicides to compensate and replenish the seedbank.
      PubDate: 2017-11-02T09:16:04.552318-05:
      DOI: 10.1002/ps.4784
  • Does multigenerational exposure to hormetic concentrations of imidacloprid
           precondition aphids for increased insecticide tolerance'
    • Authors: Rachel R Rix; G Christopher Cutler
      Abstract: BACKGROUNDHormetic preconditioning, whereby exposure to mild stress primes an organism to better tolerate subsequent stress, is well documented. It is unknown if exposure to hormetic concentrations of insecticide can trans-generationally prime insects to better tolerate insecticide exposure, or whether exposure to hormetic concentrations of insecticide can induce mutations in genes responsible for insecticide resistance. Using the aphid Myzus persicae (Sulzer) and the insecticide imidacloprid as a model, we examined if exposure to mildly toxic and hormetic concentrations of imidacloprid reduced aphid susceptibility to insecticides across four generations, and whether such exposures induced mutations in the imidacloprid binding site in post-synaptic nicotinic acetylcholine receptors.RESULTSChronic, multigenerational exposure of aphids to hormetic concentrations of imidacloprid primed offspring to better survive exposure to certain concentrations of imidacloprid, but not exposure to spirotetramat, an insecticide with a different mode of action. Exposure to hormetic and mildly toxic concentrations of imidacloprid did not result in mutations in any of the examined nicotinic acetylcholine receptor subunits.CONCLUSIONOur findings demonstrate that exposure to hormetic concentrations of insecticide can prime insects to better withstand subsequent chemical stress, but this is dependent upon the insecticide exposure scenario, and may be subtle over generations. © 2017 Society of Chemical Industry
      PubDate: 2017-11-02T09:10:25.6432-05:00
      DOI: 10.1002/ps.4731
  • Effects of fluorine-containing usnic acid and fungus Beauveria bassiana on
           the survival and immune–physiological reactions of Colorado potato
           beetle larvae
    • Authors: Vadim Yu Kryukov; Oksana G Tomilova, Olga A Luzina, Olga N Yaroslavtseva, Yuriy B Akhanaev, Maksim V Tyurin, Bahytzhan A Duisembekov, Nariman F Salakhutdinov, Viktor V Glupov
      Abstract: BACKGROUNDThe search for compounds that interact synergistically with entomopathogenic fungi is aimed at enhancing the efficacy and stability of biological products against pest insects, for example, against the Colorado potato beetle (CPB). We hypothesized that fluorine-containing derivatives of usnic acid (FUA) might be candidates for the development of multicomponent bio-insecticides. The aim of this study was to analyze the co-influence of FUA and Beauveria bassiana on the survival and immune–physiological reactions of CPB larvae.RESULTSSynergy between FUA and B. bassiana was observed after treatment of second, third and fourth larvae instars under laboratory conditions. Furthermore, synergy was observed in field trials in continental climate conditions in southeastern Kazakhstan. In a field experiment, the median lethal time was shortened three-fold, and cumulative mortality for 15 days increased by 36% in the combined treatment compared with a fungal infection alone. FUA treatment delayed larval development, decreased the total hemocyte count, and increased both the phenoloxidase activity in integuments and the detoxification enzyme rate in hemolymph. A combined treatment with fungus and FUA led to increases in the aforementioned changes.CONCLUSIONToxicosis caused by FUA provides a stable synergistic effect between FUA and B. bassiana. The combination can be promising for the development of highly efficient products against CPB. © 2017 Society of Chemical Industry
      PubDate: 2017-11-02T06:15:35.52696-05:0
      DOI: 10.1002/ps.4741
  • Development and relative fitness of Cry1C resistance in Chilo suppressalis
    • Authors: Hui Tang; Geng Chen, Fajun Chen, Lanzhi Han, Yufang Peng
      Abstract: BACKGROUNDChilo suppressalis is an important lepidopteran rice pest in the rice-growing areas of China, and the development of transgenic rice expressing the Cry1C insecticidal protein has provided a useful strategy for controlling this pest. However, insect resistance is a major threat to the durability of cry1C rice. Thus, evaluation of the risk of insect resistance before the commercial use of cry1C rice is crucial.RESULTSThis study investigated the development of C. suppressalis resistance to Cry1C protein and the relative fitness of Cry1C-resistant and -susceptible strains on different Bt rice lines. The LC50 value of the Cry1C-resistant strain increased 42.6-fold after 41 generations of selection, and the estimated realized heritability (h2) of Cry1C resistance was 0.096 in C. suppressalis. Moreover, the Cry1C-resistant strain displayed high fitness on the cry1C line, but not on the cry1Ab and cry1Ab + cry1C lines and was not cross-resistant to Cry1Ab.CONCLUSIONSThese findings suggest that C. suppressalis has the potential to develop resistance to Cry1C, although the rate of evolution is low. The pyramiding of the cry1A and cry1C genes in Bt rice is an effective strategy for delaying the evolution of resistance in C. suppressalis and sustainably maintaining the utility of Bt rice. © 2017 Society of Chemical Industry
      PubDate: 2017-11-02T03:45:48.728876-05:
      DOI: 10.1002/ps.4740
  • Insecticide susceptibilities of the two rice planthoppers Nilaparvata
           lugens and Sogatella furcifera in East Asia, the Red River Delta, and the
           Mekong Delta
    • Authors: Masaya Matsumura; Sachiyo Sanada-Morimura, Akira Otuka, Shoji Sonoda, Dinh Van Thanh, Ho Van Chien, Phan Van Tuong, Phung Minh Loc, Ze-Wen Liu, Zeng-Rong Zhu, Jian-Hong Li, Gang Wu, Shou-Horng Huang
      Abstract: BACKGROUNDThe two rice planthoppers, Nilaparvata lugens and Sogatella furcifera, have different life cycles in the regions of East Asia, the Red River Delta, and the Mekong Delta. The susceptibilities of these species to a range of insecticides have not previously been compared among the three regions over multiple years. Here, we describe the differences and similarities in insecticide susceptibilities of the two species among the three regions in 2006–2011.RESULTSIn all three regions in 2006 − 2011, N. lugens developed high and moderate levels of resistance to imidacloprid and thiamethoxam, respectively, but this species did not develop resistance to fipronil. In contrast, S. furcifera developed a high level of resistance to fipronil. The ranges in 50% lethal dose (LD50) values for N. lugens treated with both imidacloprid and thiamethoxam were similar over time between East Asia and the Red River Delta, and were different in the Mekong Delta.CONCLUSIONThe results support the idea that resistant populations migrate from the Red River Delta region to East Asia. Therefore, continuous monitoring of the susceptibility of N. lugens to insecticides in the Red River Delta is very important for insecticide resistance management in East Asia. © 2017 Society of Chemical Industry
      PubDate: 2017-11-02T03:45:40.421503-05:
      DOI: 10.1002/ps.4729
  • Comparison of a new air-assisted sprayer and two conventional sprayers in
           terms of deposition, loss to the soil and residue of azoxystrobin and
           tebuconazole applied to sunlit greenhouse tomato and field cucumber
    • Authors: Yanjie Li; Yifan Li, Xiang Pan, Qing X Li, Ronghua Chen, Xuesheng Li, Canping Pan, Jianli Song
      Abstract: BACKGROUNDPlant protection products (PPPs) are applied in China and many other developing countries with knapsack sprayers at high volumes with coarse spray quality, resulting in a high percentage of pesticide losses. In this study, a new air-assisted electric knapsack sprayer and two conventional knapsack sprayers were evaluated in terms of pesticide deposition, residues and loss into the soil. Artificial targets fixed to the upper side and underside of the leaf surface in six zones (at two depths and three heights) were used to collect the deposition, which were analyzed by liquid chromatography triple-quadrupole mass spectrometry.RESULTSThe air-assisted electric knapsack sprayer produced more deposition and better penetrability and uniformity than the two traditional spraying methods. In particular, the air-assisted electric knapsack sprayer reduced pesticide losses to the soil by roughly 37% to 75% and deposited 1.18 and 1.24 times more pesticide than the manual air-pressure and battery-powered knapsack sprayers, respectively. The residues of azoxystrobin and tebuconazole in tomato and cucumber were below the maximum residue limits (MRLs).CONCLUSIONIn general, use of the the air-assisted electric knapsack sprayer in tomato and cucumber crops could improve the effectiveness of PPPs, reduce the risk of contamination and protect food safety. © 2017 Society of Chemical Industry
      PubDate: 2017-11-02T02:55:52.646778-05:
      DOI: 10.1002/ps.4728
  • Novel HPPD inhibitors: triketone 2H-benzo[b][1,4]oxazin-3(4H)-one analogs
    • Authors: Hua-Bin Li; Lei Li, Jun-Xian Li, Ting-Feng Han, Jing-Li He, You-Quan Zhu
      Abstract: BACKGROUNDHerbicides that inhibit 4-hydroxyphenylpyruvate dioxygenase (HPPD, EC are very important for grass weed control. In order to discover novel HPPD herbicides, a series of triketone 2H-benzo[b] oxazin-3(4H)-one analogs was designed and synthesized.RESULTSIn comparison with the commercial triketone HPPD herbicide mesotrione (IC50 = 0.252 μM), some of these new triketone analogs displayed excellent HPPD inhibitory potency in vitro, for example B39 (IC50 = 0.172 μM) and B41 (IC50 = 0.156 μM). In addition, some of these compounds exhibited pre- and post-emergence herbicidal activity similar to mesotrione when applied at 375 g/ha.CONCLUSIONMany of the title compounds described in this paper could be important lead structures for the further development of novel HPPD herbicides. © 2017 Society of Chemical Industry
      PubDate: 2017-11-01T04:45:35.944914-05:
      DOI: 10.1002/ps.4739
  • Epigenetic regulation – contribution to herbicide resistance in
    • Authors: Catarine Markus; Ales Pecinka, Ratna Karan, Jacob N Barney, Aldo Merotto
      Abstract: Continuous use of herbicides has resulted in the evolution of resistance to all major herbicide modes of action worldwide. Besides the well-documented cases of newly acquired resistance through genetic changes, epigenetic regulation may also contribute to herbicide resistance in weeds. Epigenetics involves processes that modify the expression of specific genetic elements without changes in the DNA sequence, and play an important role in re-programming gene expression. Epigenetic modifications can be induced spontaneously, genetically or environmentally. Stress-induced epigenetic changes are normally reverted soon after stress exposure, although in specific cases they can also be carried over multiple generations, thereby having a selective benefit. Here, we provide an overview of the basis of epigenetic regulation in plants and discuss the possible effect of epigenetic changes on herbicide resistance. The understanding of these epigenetic changes would add a new perspective to our knowledge of environmental and management stresses and their effects on the evolution of herbicide resistance in weeds. © 2017 Society of Chemical Industry
      PubDate: 2017-11-01T02:40:27.910767-05:
      DOI: 10.1002/ps.4727
  • Grass Cell Walls Have a Role in the Inherent Tolerance of Grasses to the
           Cellulose Biosynthesis Inhibitor Isoxaben
    • Authors: Chad Brabham; Jozsef Stork, Michael Barrett, Seth DeBolt
      Abstract: BACKGROUNDCellulose biosynthesis inhibitors (CBIs) are pre-emergence herbicides that inhibit anisotropic cell expansion resulting in a severely swollen and stunted growth phenotype.Resistance to group 21 CBIs, such as isoxaben, is conferred by missense mutations in CELLOSE SYNTHASE A (CesA) genes required for primary cell wall synthesis, concluding that this is their in vivo target.RESULTSHerein, we show that grasses exhibit tolerance to group 21 CBIs and explore the mechanism of tolerance to isoxaben in the grass Brachypodium distachyon (L.). Comparative genomics failed to identify synonymous point mutations that have been found to confer isoxaben resistance in the dicot Arabidopsis thaliana (L.). Brachypodium did not metabolize 14C-isoxaben. We next explored the role of grass-specific non-cellulosic cell wall components, specifically the hemicellulose polysaccharide mix linkage glucans (MLG), as a potential tolerance mechanism by compensating for the loss of cellulose during cell elongation. A partial-transcriptional knockdown T-DNA insertion was found in a key MLG synthesis gene, Cellulose synthase-like F6 (CslF6) and this mutant was found to be 2.1 times more sensitive to isoxaben than wild-type plants.CONCLUSIONThese data suggest that the composition and compensatory response of grass cell walls may be a factor in conferring tolerance to group 21 CBIs.
      PubDate: 2017-10-31T07:35:19.681991-05:
      DOI: 10.1002/ps.4779
  • Increased Chalcone Synthase (CHS) expression is associated with dicamba
           resistance in Kochia scoparia
    • Authors: Dean J. Pettinga; Junjun Ou, Eric L. Patterson, Mithila Jugulam, Philip Westra, Todd A. Gaines
      Abstract: BACKGROUNDResistance to the synthetic auxin herbicide dicamba is increasingly problematic in Kochia scoparia. The resistance mechanism in an inbred dicamba-resistant K. scoparia line (9425R) was investigated using physiological and transcriptomics (RNA-Seq) approaches.RESULTSNo differences were found in dicamba absorption or metabolism between 9425R and a dicamba-susceptible line, but 9425R was found to have significantly reduced dicamba translocation. Known auxin-responsive genes ACC synthase (ACS) and indole-3-acetic acid amino synthetase (GH3) were transcriptionally induced following dicamba treatment in dicamba-susceptible K. scoparia but not in 9425R. Chalcone synthase (CHS), the gene regulating synthesis of the flavonols quertecin and kaemperfol, was found to have two-fold higher transcription in 9425R both without and 12 h after dicamba treatment. Increased CHS transcription co-segregated with dicamba resistance in a forward genetics screen using an F2 population.CONCLUSIONPrior work has shown that the flavonols quertecin and kaemperfol compete with auxin for intercellular movement and vascular loading via ATP-binding cassette subfamily B (ABCB) membrane transporters. The results of this study support a model in which constitutively increased CHS expression in the meristem produces more flavonols that would compete with dicamba for intercellular transport by ABCB transporters, resulting in reduced dicamba translocation.
      PubDate: 2017-10-30T09:20:24.620999-05:
      DOI: 10.1002/ps.4778
  • Early flowering and rapid grain filling determine early maturity and
           escape from harvesting in weedy rice
    • Authors: Can Zhao; Wenrong Xu, Xiaoling Song, Weimin Dai, Lei Dai, Zheng Zhang, Sheng Qiang
      Abstract: BACKGROUNDEarly maturity is an important trait that is essential to the survival of weedy rice. To explore the mechanism of early maturity in weedy rice, the reproductive development of a large sample of weedy rice accessions and cultivars was compared in a common garden study. A selected sample of both weedy and cultivated rice was sown at different dates in two years to study in more detail their flowering and grain-filling patterns.RESULTSThe weedy rice from three major cropping regions matured 7-8 days earlier than their associated cultivars. Representative weedy rice accessions planted on conventional sowing dates flowered 3-26 days earlier than cultivars; delayed sowing caused divergence in the flowering regimes in weedy rice. However, regardless of the sowing date, weedy rice filled its grain 7-21 days faster than cultivars in both study years. Vegetative and reproductive traits of weedy and cultivated rice have different patterns of variation with delayed planting.CONCLUSIONEarly maturity is an essential factor determining the persistence of weedy rice by contributing to the escape of its seed from being harvested with the rice crop. Both early flowering and shorter grain-filling stages determine early maturity, and flowering is more plastic than grain filling. © 2017 Society of Chemical Industry
      PubDate: 2017-10-27T04:21:56.195931-05:
      DOI: 10.1002/ps.4730
  • Multiple resistance to glyphosate, paraquat and ACCase-inhibiting
           herbicides in Italian ryegrass populations from California: Confirmation
           and mechanisms of resistance
    • Authors: Parsa Tehranchian; Vijay Nandula, Mithila Jugulam, Karthik Putta, Marie Jasieniuk
      Abstract: BACKGROUNDGlyphosate, paraquat and acetyl CoA carboxylase (ACCase)-inhibiting herbicides are widely used in California annual and perennial cropping systems. Recently, glyphosate, paraquat, and ACCase- and acetolactate synthase (ALS)-inhibitor resistance was confirmed in several Italian ryegrass populations from the Central Valley of California. This research characterized the possible mechanisms of resistance.RESULTSMultiple-resistant populations (MR1, MR2) are resistant to several herbicides from at least three modes of action. Dose–response experiments revealed that the MR1 population was 45.9, 122.7, and 20.5-fold, and the MR2 population was 24.8, 93.9, and 4.0-fold, less susceptible to glyphosate, sethoxydim and paraquat, respectively, than the Sus population. Accumulation of shikimate in herbicide-susceptible (Sus) plants was significantly greater than in MR plants 32 h after light pretreatments. Glyphosate resistance in MR plants was at least partially due to Pro106-to-Ala and Pro106-to-Thr substitutions at site 106 of 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). EPSPS gene copy number and expression level were similar in plants from the Sus and MR populations. An Ile1781-to-Leu substitution in ACCase of MR plants conferred a high level of resistance to sethoxydim and cross-resistance to other ACCase-inhibitors. Radiolabeled herbicide studies and phosphorimaging indicated that MR plants had restricted translocation of 14C-paraquat to untreated leaves compared to Sus plants.CONCLUSIONThis study shows that multiple herbicide resistance in Italian ryegrass populations in California, USA, is due to both target-site and non-target-site resistance mechanisms.
      PubDate: 2017-10-26T10:55:23.247403-05:
      DOI: 10.1002/ps.4774
  • Introduction of a putative biocontrol agent into a range of Phytoplasma-
           and Liberibacter-susceptible crop plants
    • Authors: Ofir Lidor; Orit Dror, Dor Hamershlak, Nofar Shoshana, Eduard Belausov, Tirtza Zahavi, Netta Mozes-Daube, Vered Naor, Einat Zchori-Fein, Lilach Iasur-Kruh, Ofir Bahar
      Abstract: BACKGROUNDPhytoplasma, the causative agent of bois-noir disease of grapevines, are vectored by the planthopper Hyalesthes obsoletus (Hemiptera: Cixiidae). A Dyella-like bacterium (DLB) isolated from H. obsoletus inhibits the growth of Spiroplasma melliferum, a cultivable relative of phytoplasma. Additional evidence suggests that DLB can reduce the symptoms of yellows disease in grapevine plantlets. The present aim was to test whether DLB could colonize a range of Phytoplasma- and Liberibacter-sensitive crop plants, and thus assess its potential agricultural use.RESULTSVitex agnus-castus – the preferred host plant of H. obsoletus was found to be a natural host of DLB, which was successfully introduced into a range of crop plants belonging to seven families. The most effective DLB application method was foliar spraying. Microscopy observation revealed that DLB aggregated on the leaf surface and around the stomata, suggesting this is its route of entry. DLB was also present in the vascular tissues of plants, indicating that it moved systemically through the plant.CONCLUSIONSDLB is a potential biocontrol agent and its broad spectrum of host plants indicates the possibility of its future use against a range of diseases caused by phloem-limited bacteria.
      PubDate: 2017-10-26T10:37:15.732905-05:
      DOI: 10.1002/ps.4775
  • Characterization of field-evolved resistance to Bacillus
           thuringiensis-derived Cry1F δ-endotoxin in Spodoptera frugiperda
           populations from Argentina
    • Authors: Desmi I. Chandrasena; Ana M. Signorini, Gustavo Abratti, Nicholas P. Storer, Magdalena L. Olaciregui, Analiza P. Alves, Clinton D. Pilcher
      Abstract: BACKGROUNDTransgenic maize (Zea mays L.) event TC1507 (Herculex® I insect protection), expressing Cry1F δ-endotoxin derived from Bacillus thuringiensis var. aizawai, was commercialized in 2003 in the Americas. Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) susceptibility to Cry1F was monitored annually across several regions in Argentina using diagnostic concentration bioassays. Reduced performance of TC1507 maize against S. frugiperda was reported in 2013. A resistant population was established in the laboratory and the dominance of Cry1F resistance was characterized. RESULTS: During 2012–2015, high-survivorship of several populations was observed in the resistance monitoring program. Reciprocal crosses of a Cry1F-resistant population with a Cry1F-susceptible population were evaluated to calculate effective dominance (DML) based on mortality levels observed at 100 µg/ml Cry1F. Two additional dominance levels (DLC and DEC) were calculated using lethal (LC50) or effective concentration (EC50) derived from concentration-response bioassays. Estimates indicated that Cry1F resistance in S. frugiperda in Argentina was either highly-recessive (DML=0.005) or incompletely recessive (DLC < 0.26 and DEC
      PubDate: 2017-10-26T10:26:48.03414-05:0
      DOI: 10.1002/ps.4776
  • Microbiome facilitated pest resistance – potential problem and uses
    • Authors: Jonathan Gressel
      Abstract: Microbiome organisms can degrade environmental xenobiotics including pesticides, conferring resistance to most types of pests. Some cases of pesticide resistance in insects, nematodes, and weeds are now documented to be due to microbiome detoxification, and is a demonstrated possibility with rodents. Some cases of metabolic resistance may have been misattributed to pest metabolism, and not to organisms in the microbiome, as few researchers use axenic pests in studying pesticide metabolism. Instances of microbiomes evolving pesticide resistance contributing to resistance of their hosts may become more common due the erratic nature of climate change, as microbiome populations typically increase and evolve faster in stressful conditions. Conversely, microbiome organisms can be engineered to provide crops and beneficial insects with needed resistances to herbicides and insecticides, respectively, but there has not been sufficient efficacy to achieve commercial products useful at the field level, even with genetically engineered microbiome organisms.
      PubDate: 2017-10-26T10:05:24.350457-05:
      DOI: 10.1002/ps.4777
  • Experimental design matters for statistical analysis: how to handle
    • Authors: Signe M. Jensen; Frank Schaarschmidt, Andrea Onofri, Christian Ritz
      Abstract: BACKGROUNDNowadays, the evaluation of effects of pesticides often relies on experimental designs that involve multiple concentrations of the pesticide of interest or multiple pesticides at specific comparable concentrations and, possibly, secondary factors of interest. Unfortunately, the experimental design is often more or less neglected when analyzing data. Two data examples were analyzed using different modelling strategies: Firstly, in a randomized complete block design, mean heights of maize treated with a herbicide and one of several adjuvants were compared. Secondly, translocation of an insecticide applied to maize as a seed treatment was evaluated using incomplete data from an unbalanced design with several layers of hierarchical sampling. Extensive simulations were carried out to further substantiate the effects of different modelling strategies.RESULTSIt was shown that results from sub-optimal approaches (two-sample t-tests and ordinary ANOVA assuming independent observations) may be both quantitatively and qualitatively different from the results obtained using an appropriate linear mixed model. The simulations demonstrated that the different approaches may lead to differences in coverage percentages of confidence intervals and type I error rates, confirming that misleading conclusions can easily happen when an inappropriate statistical approach is chosen.CONCLUSIONTo ensure that experimental data are summarized appropriately, avoiding misleading conclusions, the experimental design should duly be reflected in the choice of statistical approaches and models. We recommend that author guidelines should explicitly point out that the authors need to indicate how the statistical analysis reflects the experimental design.
      PubDate: 2017-10-24T10:15:22.516359-05:
      DOI: 10.1002/ps.4773
  • Voltage-sensitive sodium channel mutations S989P+V1016G in Aedes aegypti
           confer variable resistance to pyrethroids, DDT and oxadiazines
    • Authors: Leticia B. Smith; Shinji Kasai, Jeffrey G. Scott
      Abstract: BACKGROUNDAedes aegypti is a vector of several important human pathogens. Especially during disease outbreaks, control efforts rely primarily on pyrethroid insecticides for adult mosquito control. A. aegypti has developed resistance nearly everywhere it occurs and insecticides are used. An important mechanism of resistance is due to mutations in the voltage-sensitive sodium channel (Vssc) gene. Two mutations in particular, S989P+V1016G, commonly occur together in parts of Asia.RESULTSWe have created a strain (IsoKDR) that contains the Vssc mutations S989P+V1016G as the only mechanism of pyrethroid resistance within the genetic background of Rockefeller (ROCK), a susceptible lab strain. We created IsoKDR by crossing the pyrethroid resistant strain Singapore with ROCK followed by four backcrosses with ROCK and Vssc S989P+V1016G genotype selections. We determined the levels of resistance conferred to seventeen structurally diverse pyrethroids, the organochloride DDT, and oxadiazines (VSSC blockers) indoxacarb (proinsecticide) and DCJW (the active metabolite of indoxacarb). The levels of resistance to the pyrethroids were variable ranging from 21- to 107-fold, but no clear pattern between resistance and chemical structure was observed. Resistance is inherited as an incompletely recessive trait. IsoKDR had a>2,000-fold resistance to DDT, 37.5-fold cross-resistance to indoxacarb (37.5-fold) and 13.4-fold cross-resistance to DCJW.CONCLUSIONEtofenprox (and DDT) should be avoided in areas where Vssc mutations S989P+V1016G exist at high frequencies. We found that pyrethroid structure cannot be used to predict the level of resistance conferred by kdr. These results provide useful information for resistance management and for better understanding pyrethroid interactions with VSSC.
      PubDate: 2017-10-24T08:15:39.691737-05:
      DOI: 10.1002/ps.4771
  • Changes in field dose–response curves for demethylation inhibitor (DMI)
           and quinone outside inhibitor (QoI) fungicides against Zymoseptoria
           tritici, related to laboratory sensitivity phenotyping and genotyping
    • Authors: Jonathan J Blake; Paul Gosling, Bart A Fraaije, Fiona J Burnett, Stuart M Knight, Steven Kildea, Neil D Paveley
      Abstract: BACKGROUNDInsensitivity of Zymoseptoria tritici to demethylation inhibitor (DMI) and quinone outside inhibitor (QoI) fungicides has been widely reported from laboratory studies, but the relationships between laboratory sensitivity phenotype or target site genotype and field efficacy remain uncertain. This article reports field experiments quantifying dose–response curves, and investigates the relationships between field performance and in vitro half maximal effective concentration (EC50) values for DMIs, and the frequency of the G143A substitution conferring QoI resistance.RESULTSData were analysed from 83 field experiments over 21 years. Response curves were fitted, expressed as percentage control, rising towards an asymptote with increasing dose. Decline in DMI efficacy over years was associated with a decrease in the asymptote, and reduced curvature. Field ED50 values were positively related to in vitro EC50 values for isolates of Z. tritici collected over a 14-year period. Loss of QoI efficacy was expressed through a change in asymptote. Increasing frequency of G143A was associated with changes in field dose–response asymptotes.CONCLUSIONNew resistant strains are often detected by resistance monitoring and laboratory phenotyped/genotyped before changes in field performance are detected. The relationships demonstrated here between laboratory tests and field performance could aid translation between laboratory and field for other fungicide groups. © 2017 Society of Chemical Industry
      PubDate: 2017-10-24T04:31:38.157142-05:
      DOI: 10.1002/ps.4725
  • Synthesis and structure–activity relationships of carbohydrazides and
           1,3,4-oxadiazole derivatives bearing an imidazolidine moiety against the
           yellow fever and dengue vector, Aedes aegypti
    • Authors: Fatih Tok; Bedia Kocyigit-Kaymakcioglu, Nurhayat Tabanca, Alden S Estep, Aaron D Gross, Werner J Geldenhuys, James J Becnel, Jeffrey R Bloomquist
      Abstract: BACKGROUND1,3,4-Oxadiazole and imidazolidine rings are important heterocyclic compounds exhibiting a variety of biological activities. In this study, novel compounds with oxadiazole and imidazolidine rings were synthesized from 3-(methylsulfonyl)-2-oxoimidazolidine-1-carbonyl chloride and screened for insecticidal activities. The proposed structures of the 17 synthesized compounds were confirmed using elemental analysis, infrared (IR), proton nuclear magnetic resonance (1H-NMR), and mass spectroscopy.RESULTSNone of the compounds showed larvicidal activity at the tested concentrations against first-instar Aedes aegypti larvae. However, nine compounds exhibited promising adulticidal activity, with mortality rates of ≥80% at 5 µg per mosquito. Further dose–response bioassays were undertaken to determine median lethal dose (LD50) values. Compounds 1, 2b, 2c, 2d, 2 g, 3b, 3c, 3 g, and 3 h were effective, with typical LD50 values of about 5 − 10 µg per mosquito against female Ae. aegypti. Compounds 2c (bearing a nitro group on the aromatic ring; LD50 = 2.80 ± 0.54 µg per mosquito) and 3 h (double halogen groups at 2,4 position on the phenyl ring; LD50 = 2.80 ± 0.54 µg per mosquito) were the most promising compounds.CONCLUSIONPreliminary mode of action studies failed to show consistent evidence of either neurotoxic or mitochondria-directed effects. Further chemical synthesis within this series may lead to the development of new effective insecticides. © 2017 Society of Chemical Industry
      PubDate: 2017-10-23T07:45:38.312174-05:
      DOI: 10.1002/ps.4722
  • Herbicide discovery in light of rapidly spreading resistance and ever
           increasing regulatory hurdles
    • Authors: Bodo Peters; Harry J Strek
      Abstract: According to the UN the global population is expected to grow to almost 10 billion people in 2050. This means that the demand for food, feed and fiber will double while at the same time agriculture is being challenged by a scarcity of water, global warming, less land available for farming, protection of natural habitats, demand for biodiversity on farms and other factors. In addition crop protection products are under pressure from rapidly spreading resistance and increasing regulatory requirements. Many regulatory bodies are also moving away from a risk assessment approach to a more hazard-based approach to grant registrations. Nevertheless, chemical crop protection compounds are still attractive and necessary to combat pests, and in particular, weeds. Industry has increased efforts to find new molecules that are highly biologically effective on target species, including resistant populations, while safe for non-target organisms. In order to manage resistance in the future, a diverse toolbox that includes herbicides covering a variety of different chemistries and modes of action, combined with non-chemical measures in integrated systems, is indispensable. However, discovering an herbicide and getting it registered and to the market is an extremely complex endeavor full of risk, much of it incalculable.
      PubDate: 2017-10-20T10:15:21.912061-05:
      DOI: 10.1002/ps.4768
  • Protective effects of the egg stalk of Paratrioza sinica (Hemiptera:
           Psyllidae) at various angles and spacings against three predaceous
           coccinellids, Harmonia axyridis, Coccinella septempunctata and Hippodamia
           variegata (Coleoptera: Coccinellidae)
    • Authors: Pengxiang Wu; Baoxu Ma, Shuo Yan, Jing Xu, Jia He, Rong Zhang, Runzhi Zhang
      Abstract: BACKGROUNDParatrioza sinica is a major pest of wolfberry (Lycium barbarum). Coccinellids can effectively control various developmental stages of P. sinica but not the stalked egg. To investigate the protective role of egg stalks against the predaceous coccinellids Harmonia axyridis, Coccinella septempunctata and Hippodamia variegata, we studied the functional responses to, and effects of, two factors: the angle between the egg stalk and the leaf plane, and the spacing between egg stalks.RESULTSThe searching rate, handling time and theoretical maximum egg consumption of H. variegata were optimal among the three ladybug species. Egg consumption by coccinellids was maximum and minimum at stalk angles of 0° and 90°, respectively. The average reduction in the rate of egg consumption when the stalk angle was 90° relative to 0° was significantly smaller for larvae of coccinellids compared with adults, and for H. variegata compared with the other two species. Optimal spacing of eggs for consumption by predators varied with the predator species and their developmental stage, and was close to the body length of the predators.CONCLUSIONThe egg stalk serves as a physical protection against predators. The evolutionary selective advantage of the egg stalk in providing protection against predators requires more attention. Appropriate selection of predators and irrigation strategies may improve control of P. sinica. © 2017 Society of Chemical Industry
      PubDate: 2017-10-20T02:35:29.28892-05:0
      DOI: 10.1002/ps.4713
  • Effect of the combined application of microencapsulated synthetic
           oviposition pheromone (MSP) with different larvicidal agents on the
           oviposition of Culex pipiens biotype molestus
    • Authors: Antonios Michaelakis; Dimitrios P Papachristos, Christos I Rumbos, Christos G Athanassiou
      Abstract: BACKGROUNDAttract-and-kill strategies, in which a behavior-modifying stimulus (e.g. a pheromone) is integrated with a pest control agent, have lately attracted increased interest for mosquito control. Previously, it was demonstrated that the polyurea microencapsulated synthetic oviposition pheromone 6-acetoxy-5-hexadecanolide (MSP) was sufficiently attractive to gravid females of Culex pipiens L. biotype molestus Førskal (Diptera: Culicidae) for a period of 40 days. Furthermore, it was shown that MSP could be effectively combined with the organophosphate temephos to achieve efficient mosquito control. In the present study, the effect of the combined application of MSP with commonly used larvicides on the oviposition response of Cx. p. biotype molestus females over time was investigated in two-choice oviposition bioassays. As larvicides, the insect growth regulator diflubenzuron and the bacterial insecticide spinosad were evaluated at their lowest recommended label dose, whereas temephos was used as a control.RESULTSWhen MSP was applied in combination with diflubenzuron, the attractancy of MSP to gravid females was in all cases negatively affected, as fewer egg rafts were laid in pots treated with MSP and diflubenzuron compared with MSP alone. Spinosad did not reduce, but rather increased, the attractive effect of the oviposition pheromone at the beginning of the bioassay (at 2 days of ageing) when co-applied; however, the observed attractive effect was significantly reduced after 7 days of ageing and remained stable at the same level until the termination of the bioassay. Finally, the oviposition pattern of egg rafts laid on the pot with MSP and temephos was similar to that of egg rafts laid on the pot with MSP alone, showing that temephos did not significantly affect MSP activity.CONCLUSIONThe results of the present study highlight the effects of the combined application of MSP with spinosad and diflubenzuron on the oviposition of gravid Cx. p. biotype molestus females, which in most cases eliminated the attractive effect of MSP. © 2017 Society of Chemical Industry
      PubDate: 2017-10-20T02:10:20.797998-05:
      DOI: 10.1002/ps.4719
  • Nematicidal activity of grammicin produced by Xylaria grammica KCTC
           13121BP against Meloidogyne incognita
    • Authors: Tae Yoon Kim; Ja Yeong Jang, Nan Hee Yu, Won Jae Chi, Chang-Hwan Bae, Joo Hong Yeo, Ae Ran Park, Jae-Seon Hur, Hae Woong Park, Ji-Yeon Park, Jong-Hwan Park, Sung Ki Lee, Jin-Cheol Kim
      Abstract: BACKGROUNDThe endolichenic fungus Xylaria grammica KCTC 13121BP showed strong nematicidal activity against Meloidogyne incognita. This study aimed to identify the nematicidal metabolites and to evaluate the efficacy of the strain as a biocontrol agent under pot and field conditions.RESULTSBioassay-guided fractionation and instrumental analyses led to grammicin being identified as the nematicidal metabolite. Because patulin is a mycotoxic isomer of grammicin and is known to have strong antibacterial and cytotoxic activities, several biological activities of the two compounds were compared. Grammicin showed strong second-stage juvenile killing and egg-hatching inhibitory effects, with a 50% effective concentration at 72 h (EC50/72 h) of 15.9 µg/mL and a 50% effective concentration at 14 days (EC50/14 days) of 5.87 µg/mL, respectively, whereas patulin was virtually inactive in both respects. Patulin was strongly active toward various phytopathogenic bacteria in vitro, whereas grammicin was weakly so. Patulin at the concentration range of 0.1–10 µg/mL also showed dose-dependent cytotoxicity toward the human first-trimester trophoblast cell line SW.71, whereas grammicin was not toxic toward this cell line. In pot and field experiments, a wettable powder-type formulation and fermentation broth filtrate of X. grammica KCTC 13121BP effectively suppressed the development of root-knot nematode disease on tomato and melon plants.CONCLUSIONThe results suggest that X. grammica and grammicin may have potential applications for control of root-knot nematode disease of various crops. © 2017 Society of Chemical Industry
      PubDate: 2017-10-19T07:30:24.050538-05:
      DOI: 10.1002/ps.4717
  • Sequential sampling plans and economic injury levels for Empoasca kraemeri
           on common bean crops at different technological levels
    • Authors: Marcelo Fialho de Moura; Mayara Cristina Lopes, Renata Ramos Pereira, Jorgiane Benevenute Parish, Mateus Chediak, Lucas de Paulo Arcanjo, Daiane das Graças do Carmo, Marcelo Coutinho Picanço
      Abstract: BACKGROUNDEmpoasca kraemeri is an important pest on common bean crops at different technological levels. However, for this pest on this crop, economic injury levels have not yet been determined and plan for sequential sampling plans has not yet been developed. Thus, the objectives of this research were to develop E. kraemeri sequential sampling plans and to determine economic injury levels in the common bean at different crop technological levels.RESULTSCommon bean plants tolerate low attack intensities of this pest (up to 1 adult plant-1). However, with an increase in attacks, there is a reduction in grain production by the plants. The economic injury levels were 0.48, 0.39 and 0.35 adults sample-1 (leaf beating on a tray) for crops with low (1200 kg ha-1), medium (1800 kg ha-1) and high (2400 kg ha-1) technological levels, respectively. Sequential sampling plans and the standardized plan produced similar decisions. However, in these decisions there was a time saving of more than 60% compared with the standardized plan.CONCLUSIONAll three economic injury levels determined and the sequential sampling plans developed in this study are suitable for incorporation into integrated management programs for common bean pests because they can be used by farmers operating at various technological levels to make adequate and rapid decisions. © 2017 Society of Chemical Industry
      PubDate: 2017-10-19T06:15:25.797366-05:
      DOI: 10.1002/ps.4720
  • Use of Biocontrol Agents and Botanicals in Integrated Management of
           Botrytis Cinerea in Table-Grape Vineyards
    • Authors: Caterina Rotolo; Rita M De Miccolis Angelini, Crescenza Dongiovanni, Stefania Pollastro, Giulio Fumarola, Michele Di Carolo, Donato Perrelli, Patrizia Natale, Francesco Faretra
      Abstract: BACKGROUNDThe increasing interest on biological control agents (BCAs) and botanicals (BOTs) is due to the increasing awareness on environmental and human health risks associated to the usage of synthetic plant protection products. The BCAs Bacillus subtilis strain QST713, Bacillus amyloliquefaciens strain D747 and Aureobasidium pullulans strains DSM14940 and DSM14941, and the BOTs Melaleuca alternifolia and terpenic extracts are proposed for the control of grey mould in vineyard. This study was aimed at evaluating their effectiveness in integrated crop management strategies and their outcomes in terms of management of fungicide resistance and residues.RESULTSIn field trials carried out on table-grape in Southern Italy, alternations or mixtures of BCAs or BOTs with the SDHI fungicide fluopyram showed efficacy up to 96% against grey mould on bunches, comparable to the chemical-reference strategy (up to 87%), while the solo use of BCAs or BOTs (up to eleven sprays) were not enough effective (< 30%) under high disease pressure. The integrated use of BCAs or BOTs reduced the spreading of SDHI-resistant conidia as well as fungicide residues in grape.CONCLUSIONSSpray schedules based on integration of BCAs or BOTs with fungicides are effective against grey mould and reduce the risk of fungicide resistance in B. cinerea and fungicide residues in grape.
      PubDate: 2017-10-17T02:46:13.951992-05:
      DOI: 10.1002/ps.4767
  • Camera traps and activity signs to estimate wild boar density and derive
           abundance indices
    • Authors: G. Massei; J. Coats, M. Lambert, S. Pietravalle, R. Gill, D. Cowan
      Abstract: BACKGROUNDPopulations of wild boar and feral pigs are increasing worldwide, in parallel with their significant environmental and economic impact. Reliable methods of monitoring trends and estimating abundance are needed to measure the effects of interventions on population size. The main aims of this study, carried out in five English woodlands were 1. to compare wild boar abundance indexed obtained from camera trap surveys and from activity signs and 2. to assess the precision of density estimates in relation to different densities of camera traps. For each woodland, we calculated a Passive Activity Index (PAI) based on camera trap surveys, rooting activity and wild boar trails on transects and estimated absolute densities based on camera trap surveys.RESULTSPAIs obtained from different methods showed similar patterns. We found significant between-year differences in abundance of wild boar using PAIs based on camera trap surveys and on trails on transects but not on signs of rooting on transects. The density of wild boar from camera trap surveys varied between 0.7 and 7 animals/km2. Increasing the density of camera traps above 9/km2 did not increase the precision of the estimate of wild boar density.CONCLUSIONPAIs based on number of wild boar trails and on camera trap data appear to be more sensitive to changes in population size than PAIs based on signs of rooting. For wild boar densities similar to those recorded in this study, 9 camera traps /km2 are sufficient to estimate the mean density of wild boar.
      PubDate: 2017-10-12T05:15:20.586822-05:
      DOI: 10.1002/ps.4763
  • Novel bisthioether derivatives containing a 1,3,4-oxadiazole moiety:
           Design, synthesis, antibacterial and nematocidal activities
    • Authors: Pei Li; Pingyi Tian, Yongzhong Chen, Xianpeng Song, Wei Xue, Linhong Jin, Deyu Hu, Song Yang, Baoan Song
      Abstract: BACKGROUNDLiterature revealed that bisthioether and 1,3,4-oxadiazole derivatives exhibited a wide variety of biological activities. In this study, a series of novel bisthioether derivatives containing a 1,3,4-oxadiazole moiety were synthesized and their antibacterial and nematocidal activities were investigated.RESULTSAmong the title compounds evaluated, compound 4f demonstrated the best antibacterial activities against rice bacterial leaf blight, rice bacterial leaf streak and citrus canker caused by Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas oryzae pv. oryzicola (Xoc), and Xanthomonas axonopodis pv. citri (Xac), respectively, with the EC50 values of 4.82, 11.15, and 16.57 μg mL–1, respectively, which were even better than those of thiodiazole copper and bismerthiazol. Meanwhile, compound 4f revealed better in vitro nematocidal activity against Caenorhabditis elegans (C. elegans) at 48 h, with a LC50 value of 2.89 μg mL–1, which was superior to those of ethoprophos and fosthiazate. In addition, the greenhouse trials indicated that compound 4f was effective in reducing rice bacterial leaf blight relative to those of thiodiazole copper and bismerthiazol.CONCLUSIONA series of novel bisthioether derivatives containing a 1,3,4-oxadiazole moiety were synthesized and bioassay results showed that compound 4f exhibited the best antibacterial and nematocidal activities.
      PubDate: 2017-10-12T05:10:36.06797-05:0
      DOI: 10.1002/ps.4762
  • Resistance to cycloxaprid in Laodelphax striatellus is associated with
           altered expression of nicotinic acetylcholine receptor subunits
    • Authors: Yueliang Zhang; Yangchun Han, Qiong Yang, Lihua Wang, Peng He, Zewen Liu, Huifang Guo, Jichao Fang
      Abstract: BACKGROUNDCycloxaprid is a new oxabridged cis-configuration neonicotinoid insecticide, the resistance development potential and underlying resistance mechanism of which were investigated in the small brown planthopper, Laodelphax striatellus (Fallén), an important agricultural pest of rice.RESULTSA cycloxaprid-resistant strain (YN-CPD) only achieved 10-fold resistance, in contrast to 106-fold resistance to buprofezin and 332-fold resistance to chlorpyrifos achieved after exposure to similar selection pressure, and the cycloxaprid selected line showed no cross-resistance to the buprofezin and chlorpyrifos-selected resistance strains. Moreover, we identified 10 nicotinic acetylcholine receptor (nAChR) subunits from the transcriptome of L. striatellus, and 6 segments had open reading frames (ORFs). While we did not find mutations in the nAChR genes of L. striatellus, subunits Lsα1 and Lsβ1 exhibited respectively 9.60-fold and 3.36-fold higher expression in the resistant strain, while Lsα8 exhibited 0.44-fold lower expression. Suppression of Lsα1 through ingestion of dsLsα1 led to an increase in susceptibility to cycloxaprid.CONCLUSIONThe findings indicate that resistance to cycloxaprid develops slowly compared to other chemicals and without cross-resistance to chlorpyrifos or buprofezin; over-expressed Lsα1 is associated with low cycloxaprid resistance levels, but the importance of over-expressed Lsβ1 and reduced expression of Lsα8 could not be excluded.
      PubDate: 2017-10-09T08:15:22.665052-05:
      DOI: 10.1002/ps.4757
  • Reversing resistance to tembotrione in an Amaranthus tuberculatus (var.
           rudis) population from Nebraska, USA with cytochrome P450 inhibitors
    • Authors: Maxwel C Oliveira; Todd A Gaines, Franck E Dayan, Eric L Patterson, Amit J Jhala, Stevan Z Knezevic
      Abstract: BACKGROUNDA population of Amaranthus tuberculatus (var. rudis) was confirmed resistant to 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibitor herbicides (mesotrione, tembotrione, and topramezone) in a seed corn/soybean rotation in Nebraska. Further investigation confirmed a non-target-site resistance mechanism in this population. The main objective of this study was to explore the role of cytochrome P450 inhibitors in restoring the efficacy of HPPD-inhibitor herbicides on the HPPD-inhibitor resistant A. tuberculatus population from Nebraska, USA (HPPD-R).RESULTSEnhanced metabolism via cytochrome P450 enzymes is the mechanism of resistance in HPPD-R. Amitrole partially restored the activity of mesotrione, whereas malathion, amitrole, and piperonyl butoxide restored the activity of tembotrione and topramezone in HPPD-R. Although corn was injured through malathion followed by mesotrione application a week after treatment, the injury was transient, and the crop recovered.CONCLUSIONThe use of cytochrome P450 inhibitors with tembotrione may provide a new way of controlling HPPD-inhibitor resistant A. tuberculatus, but further research is needed to identify the cytochrome P450 candidate gene(s) conferring metabolism-based resistance. The results presented here aid to gain an insight into non-target-site resistance weed management strategies. © 2017 Society of Chemical IndustryNon-target-site resistant Amaranthus tuberculatus is a threat for corn and soybean production in the northcentral USA. This article presents the role of cytochrome P450 inhibitors for restoring the efficacy of mesotrione, tembotrione, and topramezone on an HPPD-inhibitor resistant A. tuberculatus population from Nebraska, USA.
      PubDate: 2017-09-27T07:20:41.755886-05:
      DOI: 10.1002/ps.4697
  • Survey of the genomic landscape surrounding the
           5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene in
           glyphosate-resistant Amaranthus palmeri from geographically distant
           populations in the USA
    • Authors: William T Molin; Alice A Wright, Mark J VanGessel, William B McCloskey, Mithila Jugulam, Robert E Hoagland
      Abstract: BACKGROUNDGlyphosate resistance in Amaranthus palmeri, one of the most prevalent herbicide-resistant weeds in the USA, is attributable to amplification and increased expression of the gene encoding the target site of glyphosate, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). The EPSPS gene and the surrounding 287 kilobases (kb) of amplified sequence are unique to glyphosate-resistant plants and termed the EPSPS cassette. It has only been sequenced in one A. palmeri population from Mississippi. This research compares EPSPS cassettes in seven resistant and five sensitive populations from geographically distant locations within the USA, including Mississippi, Arizona, Kansas, Maryland, Delaware and Georgia.RESULTSPolymerase chain reaction (PCR) products from 40 primer pairs specific to the cassette were similar in size and sequence in resistant populations. Several primer pairs failed to generate PCR products in sensitive populations. Regions of the cassette sequenced in the resistant populations were found to be nearly identical to those from Mississippi. Gene expression analysis showed that both EPSPS and another gene in the cassette, a reverse transcriptase, were elevated in all resistant populations tested relative to the sensitive populations.CONCLUSIONEPSPS cassettes from distant resistant populations were nearly homologous. Considering the complexity of the cassette, and the degree of similarity among some cassette sequences, the results are consistent with the hypothesis that glyphosate resistance probably evolved once and then rapidly spread across the USA. © 2017 Society of Chemical Industry
      PubDate: 2017-09-11T02:10:34.765554-05:
      DOI: 10.1002/ps.4659
  • Evaluation of glyphosate resistance in Arabidopsis thaliana expressing an
           altered target site EPSPS
    • Authors: R Douglas Sammons; Jinsong You, Youlin Qi, Stanislaw Flasinski, Christina Kavanaugh, Jeannie Washam, Elizabeth Ostrander, Dafu Wang, Greg Heck
      Abstract: BACKGROUNDGlyphosate-resistant goosegrass has recently evolved and is homozygous for the double mutant of EPSPS (T102I, P106S or TIPS). These same mutations combined with EPSPS overexpression, have been used to create transgenic glyphosate-resistant crops. Arabidopsis thaliana (Wt EPSPS Ki ∼ 0.5 μM) was engineered to express a variant AtEPSPS-T102I, P106A (TIPA Ki = 150 μM) to determine the resistance magnitude for a more potent variant EPSPS that might evolve in weeds.RESULTSTransgenic A. thaliana plants, homozygous for one, two or four copies of AtEPSPS-TIPA, had resistance (IC50 values, R/S) as measured by seed production ranging from 4.3- to 16-fold. Plants treated in reproductive stage were male sterile with a range of R/S from 10.1- to 40.6-fold. A significant hormesis (∼ 63% gain in fresh weight) was observed for all genotypes when treated at the initiation of reproductive stage with 0.013 kg ha–1. AtEPSPS-TIPA enzyme activity was proportional to copy number and correlated with resistance magnitude.CONCLUSIONSA. thaliana, as a model weed expressing one copy of AtEPSPS-TIPA (300-fold more resistant), had only 4.3-fold resistance to glyphosate for seed production. Resistance behaved as a single dominant allele. Vegetative tissue resistance was 4.7-fold greater than reproductive tissue resistance and was linear with gene copy number. © 2017 The
      Authors . Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
      PubDate: 2017-09-07T06:45:56.729646-05:
      DOI: 10.1002/ps.4654
  • Renal neuroendocrine control of desiccation and cold tolerance by
           Drosophila suzukii
    • Authors: Selim Terhzaz; Lucy Alford, Joseph GC Yeoh, Richard Marley, Anthony J Dornan, Julian AT Dow, Shireen A Davies
      Abstract: BACKGROUNDNeuropeptides are central to the regulation of physiological and behavioural processes in insects, directly impacting cold and desiccation survival. However, little is known about the control mechanisms governing these responses in Drosophila suzukii. The close phylogenetic relationship of D. suzukii with Drosophila melanogaster allows, through genomic and functional studies, an insight into the mechanisms directing stress tolerance in D. suzukii.RESULTSCapability (Capa), leucokinin (LK), diuretic hormone 44 (DH44) and DH31 neuropeptides demonstrated a high level of conservation between D. suzukii and D. melanogaster with respect to peptide sequences, neuronal expression, receptor localisation, and diuretic function in the Malpighian tubules. Despite D. suzukii's ability to populate cold environments, it proved sensitive to both cold and desiccation. Furthermore, in D. suzukii, Capa acts as a desiccation- and cold stress-responsive gene, while DH44 gene expression is increased only after desiccation exposure, and the LK gene after nonlethal cold stress recovery.CONCLUSIONThis study provides a comparative investigation into stress tolerance mediation by neuroendocrine signalling in two Drosophila species, providing evidence that similar signalling pathways control fluid secretion in the Malpighian tubules. Identifying processes governing specific environmental stresses affecting D. suzukii could lead to the development of targeted integrated management strategies to control insect pest populations. © 2017 The
      Authors . Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.This study provides a comparative investigation between D. suzukii and D. melanogaster into stress tolerance mediation by neuroendocrine signalling that control fluid secretion in the Malpighian tubules.
      PubDate: 2017-08-29T02:31:01.631584-05:
      DOI: 10.1002/ps.4663
  • Identification and analysis of 5-enolpyruvylshikimate-3-phosphate synthase
           (EPSPS) gene from glyphosate-resistant Ochrobactrum intermedium Sq20
    • Authors: Sadiqa Firdous; Samina Iqbal, Samina Anwar, Hina Jabeen
      Abstract: BACKGROUNDGlyphosate is a herbicide that acts by inhibition of the enzyme, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), involved in the catalysis of an essential step in the biosynthesis of aromatic amino acids. The objective of this study was the isolation of glyphosate-resistant bacterial strains and subsequent characterization of the gene(s) encoding glyphosate resistance in these isolates. Using an enrichment culture technique, a glyphosate-resistant bacterium, Ochrobactrum intermedium Sq20 was isolated from glyphosate-contaminated indigenous soil and characterized.RESULTSAn open reading frame (ORF) comprising of 1353 bp potentially encoding aroAO. intermedium Sq20 was amplified from O. intermedium Sq20. It showed 97% homology with aroA genes from other Ochrobactrum spp. Physicochemical characterization revealed that aroAO. intermedium Sq20 encodes a polypeptide of 450 amino acids with a calculated molecular mass of 48.9782 kDa and an isoelectric point of 5.21. Secondary structure prediction of AroAO. intermedium Sq20 demonstrated a high percentage of random coils and α helices. Methodical optimization and validation of the protein structure helped to build a reliable protein model indicating the presence of 91.8% amino acid residues in most favoured regions. In addition, strain Sq20 was found to be capable of complete degradation of glyphosate at 500 mg L–1 initial concentration as the sole carbon and energy source within 4 days.CONCLUSIONA glyphosate-resistant bacterial strain O. intermedium Sq20 was discovered. Sequence analysis and structure modelling demonstrated that AroAO. intermedium Sq20 closely resembles class II EPSPS and possesses high glyphosate resistance. This provides a good foundation for functional analysis of experimentally derived crystal structures. The cloning and characterization of AroAO. intermedium Sq20 will further help in understanding its role at the molecular level and its potential use in the production of glyphosate-resistant transgenic crops. © 2017 Society of Chemical IndustryA glyphosate-resistant bacterial strain O. intermedium Sq20 was isolated. Sequence analysis and structure modelling demonstrated that AroAO.intermedium Sq20 closely resembles class II EPSPS which provides foundation for its functional analysis.
      PubDate: 2017-08-12T05:50:40.983879-05:
      DOI: 10.1002/ps.4624
  • The history and current status of glyphosate
    • Authors: Stephen O Duke
      Abstract: Glyphosate is the only herbicide to target the enzyme 5-enolpyruvyl-3-shikimate phosphate synthase (EPSPS). It is a high use rate, non-selective herbicide that translocates primarily to metabolic sinks, killing meristematic tissues away from the application site. Its phloem-mobile properties and slow action in killing weeds allow the herbicide to move throughout the plant to kill all meristems, making it effective for perennial weed control. Since commercialization in 1974, its use has grown to dominate the herbicide market. Much of its use is on transgenic, glyphosate-resistant crops (GRCs), which have been the dominant transgenic crops worldwide. GRCs with glyphosate provided the most effective and inexpensive weed management technology in history for a decade or more. However, as a consequence of the rapid increase in glyphosate-resistant (GR) weeds, the effectiveness of glyphosate use in GRCs is declining. Critics have claimed that glyphosate-treated GRCs have altered mineral nutrition and increased susceptibility to plant pathogens because of glyphosate's ability to chelate divalent metal cations, but the complete resistance of GRCs to glyphosate indicates that chelating metal cations do not contribute to the herbicidal activity or significantly affect mineral nutrition. The rates of increases in yields of maize, soybean, and cotton in the USA have been unchanged after high adoption rates of GRCs. Glyphosate is toxic to some plant pathogens, and thereby can act as a fungicide in GRCs. Ultra-low doses of glyphosate stimulate plant growth in glyphosate-susceptible plants by unknown mechanisms. Despite rapid and widespread increases in GR weeds, glyphosate use has not decreased. However, as GR weeds increase, adoption of alternative technologies will eventually lead to decreased use. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.Glyphosate has been the most successful herbicide in history. This perspective chronicles the reasons for its success and the impact of evolved glyphosate resistance on its current and future use.
      PubDate: 2017-08-11T03:50:34.941595-05:
      DOI: 10.1002/ps.4652
  • Lack of transgene and glyphosate effects on yield, and mineral and amino
           acid content of glyphosate-resistant soybean
    • Authors: Stephen O Duke; Agnes M Rimando, Krishna N Reddy, James V Cizdziel, Nacer Bellaloui, David R Shaw, Martin M Williams, Jude E Maul
      Abstract: BACKGROUNDThere has been controversy as to whether the glyphosate resistance gene and/or glyphosate applied to glyphosate-resistant (GR) soybean affect the content of cationic minerals (especially Mg, Mn and Fe), yield and amino acid content of GR soybean. A two-year field study (2013 and 2014) examined these questions at sites in Mississippi, USA.RESULTSThere were no effects of glyphosate, the GR transgene or field crop history (for a field with both no history of glyphosate use versus one with a long history of glyphosate use) on grain yield. Furthermore, these factors had no consistent effects on measured mineral (Al, As, Ba, Cd, Ca, Co, Cr, Cs, Cu, Fe, Ga, K, Li, Mg, Mn, Ni, Pb, Rb, Se, Sr, Tl, U, V, Zn) content of leaves or harvested seed. Effects on minerals were small and inconsistent between years, treatments and mineral, and appeared to be random false positives. No notable effects on free or protein amino acids of the seed were measured, although glyphosate and its degradation product, aminomethylphosphonic acid (AMPA), were found in the seed in concentrations consistent with previous studies.CONCLUSIONSNeither glyphosate nor the GR transgene affect the content of the minerals measured in leaves and seed, harvested seed amino acid composition, or yield of GR soybean. Furthermore, soils with a legacy of GR crops have no effects on these parameters in soybean. © 2017 Society of Chemical IndustryNo effects of the glyphosate-resistance transgene or glyphosate were found on mineral and amino acid content or yield of glyphosate-resistance soybeans.
      PubDate: 2017-08-08T03:00:57.398441-05:
      DOI: 10.1002/ps.4625
  • Conceptual considerations on exposure assessment goals for aquatic
           pesticide risks at EU level
    • Authors: Jos JTI Boesten
      Pages: 264 - 274
      Abstract: Assessment of the risk to aquatic organisms is an important aspect of pesticide registration. This assessment must be based on well-defined exposure assessment goals (EAGs). However, these goals have not yet been defined for the EU authorization procedure. The definition of an aquatic EAG has seven elements, including: type of water body, spatial dimension of this body, spatial population of water bodies, multi-year temporal population of concentrations for a single water body, and the space-time percentile combination to be selected from the spatio-temporal population of concentrations. The seven elements are split into 16 items, three which are within the risk-management domain. The remaining 13 scientific items should preferably be based on consistency with landscape-level approaches. Subdivision of the spatial population of water bodies on the occurrence of exposure routes should be avoided (although this is current practice). The multi-year temporal population of concentrations should be based on all years in rotational crops (including years without applications). Risk managers should be offered a suite of coherent packages of EAGs and effect assessment goals from which they can select the package corresponding to the desired overall level of protection. © 2017 Society of Chemical IndustryThe specification of the exposure assessment goal is an essential element of the aquatic pesticide risk assessment. This goal consists of seven elements of which three have risk management aspects.
      PubDate: 2017-10-12T07:25:48.604385-05:
      DOI: 10.1002/ps.4701
  • Limited fitness costs of herbicide-resistance traits in Amaranthus
           tuberculatus facilitate resistance evolution
    • Authors: Chenxi Wu; Adam S Davis, Patrick J Tranel
      Pages: 293 - 301
      Abstract: BACKGROUNDThe fitness cost of herbicide resistance (HR) in the absence of herbicide selection plays a key role in HR evolution. Quantifying the fitness cost of resistance, however, is challenging, and there exists a knowledge gap in this area. A synthetic (artificially generated) Amaranthus tuberculatus population segregating for five types of HR was subjected to competitive growth conditions in the absence of herbicide selection for six generations. Fitness costs were quantified by using a combination of phenotyping and genotyping to monitor HR frequency changes over generations.RESULTSIn the absence of herbicide selection, a significant fitness cost was observed for resistance to acetolactate synthase-inhibiting herbicides, but not for resistances to atrazine (non-target-site resistance mechanism), protoporphyrinogen oxidase inhibitors, 4-hydroxyphenylpryuvate dioxygenase inhibitors or glyphosate. Glyphosate resistance was conferred by multiple mechanisms in the synthetic population, and further analysis revealed that one mechanism, amplification of the 5-enolypyruvylshikimate-3-phosphate synthase gene, did decrease in frequency.CONCLUSIONOur results indicate that herbicide-resistance mitigation strategies (e.g. herbicide rotation) that rely on the existence of fitness costs in the absence of herbicide selection likely will be largely ineffective in many cases. © 2017 Society of Chemical IndustryA multigenerational study was used to measure fitness costs of herbicide-resistance traits in Amaranthus tuberculatus. Results suggest that resistance management strategies based on fitness costs of herbicide resistance, such as crop rotation, will not be particularly effective in many cases.
      PubDate: 2017-09-28T04:26:42.708996-05:
      DOI: 10.1002/ps.4706
  • The role of field dust in pesticide drift when pesticide-treated maize
           seeds are planted with vacuum-type planters
    • Authors: Arthur W Schaafsma; Victor Limay-Rios, Luis G Forero
      Pages: 323 - 331
      Abstract: BACKGROUNDNeonicotinoid-contaminated dust escaping pneumatic seeders causes exposure to non-target organisms such as pollinators. Two sources of dust have been reported: abrasion by talc which is added as seed lubricant during planting, and seed-to-seed abrasion occurring during seed handling, distribution and planting. We report a third important source that warrants remediation. Here, soil dust stirred up by planters was found to enter the vacuum air intake near seed metering devices.RESULTSThe mean quantity of dust collected from the exhaust of a commercial pneumatic planter over a number of field sites and situations was 46 g ha−1, ranging from 5.8 to 184.2 g ha−1. While the clothianidin concentration in exhaust dust declined with increasing quantity of dust, total clothianidin recovered increased linearly within the study parameters. Up to 2.4 g ha−1 of clothianidin was recovered from planter exhaust, representing approximately 12.6% of the active ingredient applied to seed. A similar pattern occurred in the laboratory on a single standing planter unit using diatomaceous earth as surrogate field dust.CONCLUSIONField dust in pneumatic metering systems contributes significantly to clothianidin contamination in planter exhaust by seed abrasion. Adding diatomaceous earth as surrogate field dust to the Heubach seed dust protocol accounted for field dust abrasion and distinguished anti-abrasive properties of seed treatments. © 2017 Society of Chemical IndustrySoil dust stirred up by pneumatic maize planters enters the vacuum air intake near seed metering devices and abrades pesticides off seed to be exhausted into atmosphere.
      PubDate: 2017-09-05T03:06:56.54913-05:0
      DOI: 10.1002/ps.4696
  • Functional response and multiple predator effects of two generalist
           predators preying on Tuta absoluta eggs
    • Authors: Georgios Michaelides; Spyros Sfenthourakis, Maria Pitsillou, Nicos Seraphides
      Pages: 332 - 339
      Abstract: BACKROUNDInteractions among invertebrate predators could affect a pest suppression. The hemipteran species Macrolophus pygmaeus (Rambur) and Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) are natural enemies of several pests in agroecosystems and coexist in tomato crops in Mediterranean countries. By using the multiplicative risk model (MRM) and the substitutive model, the multiple predator effects (MPEs) on prey suppression were calculated when two individuals of the predators foraged at the same densities on South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), eggs.RESULTSEgg consumption increased with increasing egg density and the two predators exhibited a type III functional response. Predation rates were strongly affected by prey density. Using the MRM, we found risk reduction at intraspecific treatments at high prey density. Applying the substitutive model, we detect risk enhancement at interspecific treatments at high egg density.CONCLUSIONSAt low prey densities, most of the interactions were independent, whereas at high densities most interactions were not independent and resulted in prey risk reduction, indicating antagonism between the individuals involved. We also showed that N. tenuis is a more competitive predator species for T. absoluta eggs than M. pygmaeus; however, combination of the two predator species will lead to better pest suppression at high T. absoluta population densities. © 2017 Society of Chemical IndustryConspecific and heterospecific interactions between the polyphagous predators Macrolophus pygmaeus (Rambur) and Nesidiocoris tenuis (Reuter) when preyed on the South American tomato pinworm, Tuta absoluta (Meyrick, 1917), eggs.
      PubDate: 2017-09-25T07:10:34.733631-05:
      DOI: 10.1002/ps.4703
  • Temporal and spatial distribution of insecticide-resistance mutations in
           the green peach aphid Myzus persicae (Hemiptera: Aphididae) on primary and
           secondary host plants in central Chile
    • Authors: María E Rubio-Meléndez; Daniela A Sepúlveda, Claudio C Ramírez
      Pages: 340 - 347
      Abstract: BACKGROUNDThe aphid Myzus persicae develops insensitivity to almost all classes of insecticides through target site mutations. The aim of this study was to assess the temporal and spatial distribution of resistant aphids that grow on peach trees and weeds, and establish the role of the secondary hosts as a reservoir of resistant genotypes.RESULTSThe frequency of genotypes (RR, RS, and SS) was affected by the host plant, mainly for knock-down resistance (kdr) and modified acetylcholinesterase (MACE) mutations (P < 0.05). A higher frequency of RS and RR was observed in aphids found on peach trees than on weeds. The frequency of the R allele was significantly higher (P < 0.01) than expected in autumn and on weeds for the kdr and MACE mutations, while the frequency of the S allele was high in all seasons for all insecticide-resistance mutations (P < 0.01). The most abundant multilocus genotype was characterized as being RS for the kdr mutation and SS for both super-kdr and MACE.CONCLUSIONThis study provides farm-scale evidence that weeds are not an important reservoir of the R allele, but they are for the S allele. Hence, the presence of heterozygous genotypes on peach trees is most likely attributable to weeds. © 2017 Society of Chemical IndustryThe insecticide resistance in aphids is a problem for agriculture.However, the presence of surrounding weeds, a reservoir of the S allele, contributed increasing the heterozygous genotypes on peach trees.
      PubDate: 2017-10-12T07:25:36.141109-05:
      DOI: 10.1002/ps.4708
  • Gene flow from single and stacked herbicide-resistant rice (Oryza sativa):
           modeling occurrence of multiple herbicide-resistant weedy rice
    • Authors: Joseph Dauer; Andrew Hulting, Dale Carlson, Luke Mankin, John Harden, Carol Mallory-Smith
      Pages: 348 - 355
      Abstract: BACKGROUNDProvisia™ rice (PV), a non-genetically engineered (GE) quizalofop-resistant rice, will provide growers with an additional option for weed management to use in conjunction with Clearfield® rice (CL) production. Modeling compared the impact of stacking resistance traits versus single traits in rice on introgression of the resistance trait to weedy rice (also called red rice). Common weed management practices were applied to 2-, 3- and 4-year crop rotations, and resistant and multiple-resistant weedy rice seeds, seedlings and mature plants were tracked for 15 years.RESULTSTwo-year crop rotations resulted in resistant weedy rice after 2 years with abundant populations (exceeding 0.4 weedy rice plants m–2) occurring after 7 years. When stacked trait rice was rotated with soybeans in a 3-year rotation and with soybeans and CL in a 4-year rotation, multiple-resistance occurred after 2–5 years with abundant populations present in 4–9 years. When CL rice, PV rice, and soybeans were used in 3- and 4-year rotations, the median time of first appearance of multiple-resistance was 7–11 years and reached abundant levels in 10–15 years.CONCLUSIONMaintaining separate CL and PV rice systems, in rotation with other crops and herbicides, minimized the evolution of multiple herbicide-resistant weedy rice through gene flow compared to stacking herbicide resistance traits. © 2017 Society of Chemical IndustryTo stack or not stack multiple herbicide-resistant traits into crops' Rotating single herbicide-resistant rice lines reduces the likelihood of weedy rice introgression compared to stacked trait rice.
      PubDate: 2017-10-06T09:55:22.824788-05:
      DOI: 10.1002/ps.4711
  • Effect of potassium and manganese phosphites in the control of Pythium
           damping-off in soybean: a feasible alternative to fungicide seed
    • Authors: Marcelo A Carmona; Francisco J Sautua, Pablo E Grijalba, Mariano Cassina, Oscar Pérez-Hernández
      Pages: 366 - 374
      Abstract: BACKGROUNDUse of fungicide seed treatments for control of soybean soilborne diseases such as Pythium damping-off has increased worldwide. However, emergence of Pythium strains resistant to metalaxyl-M has prompted the need for alternative technologies to fungicides for damping-off control. The use of phosphites (Phis) has been proposed as a method to control oomycetes, but their use as seed treatments in soybean is limited by the lack of information on their efficacy. The effect of potassium (K) and manganese (Mn) Phis (as seed treatments) in the control of Pythium damping-off in soybean was evaluated in vitro and in vivo. In vitro, treated seeds and a control were placed on potato dextrose agar and the damping-off severity caused by Pythium aphanidermatum (Edson) Fitzpatrick, Pythium irregulare Buisman, and Pythium ultimum Trow was assessed 5 days after incubation using an ordinal scale. In vivo, treated seeds and a control were planted in polystyrene pots and emergence was evaluated 21 days after planting.RESULTSAnalysis of the in vitro data using a multinomial generalized linear model showed that the probabilities of non-germinated, dead seeds ranged from 0.64 to 1.00 in the control and from 0 to 0.13 in the Phi treatments in each of the Pythium species. Probabilities of seed germination without or with damping-off symptoms were significantly higher for seeds treated with the Phi products than for the control. In the in vivo experiment, the Phi-based products increased seedling emergence by up to 29% on average compared with the untreated control.CONCLUSIONMn and K Phis are feasible alternatives as seed treatments to control Pythium damping-off in soybean. This study is the first, worldwide, to document the efficacy of K and Mn Phis in the control of soybean Pythium damping-off. © 2017 Society of Chemical IndustryPhosphites are a feasible alternative to control Pythium damping-off in soybean as seed treatments. This study is the first, worlwide, to document the efficacy of K and Mn Phis in the control of soybean Pythium damping off.
      PubDate: 2017-10-09T04:56:02.395035-05:
      DOI: 10.1002/ps.4714
  • Environmental fate and behaviour of the biocontrol agent Bacillus
           amyloliquefaciens CPA-8 after preharvest application to stone fruit
    • Authors: Laura Vilanova; Neus Teixidó, Josep Usall, Marta Balsells-Llauradó, Amparo Gotor-Vila, Rosario Torres
      Pages: 375 - 383
      Abstract: BACKGROUNDBacillus amyloliquefaciens strain CPA-8 has been described as an effective biocontrol agent to control brown rot in stone fruit for both preharvest and postharvest applications. However, no information about the environmental fate and behaviour of this strain under field conditions is available.RESULTSThe dispersion of the CPA-8 application was evaluated using water-sensitive papers, and complete coverage was observed on the leaves of treated trees, while
      PubDate: 2017-09-30T02:55:36.627257-05:
      DOI: 10.1002/ps.4716
  • Factors affecting trap catch in pheromone-based monitoring of saddle gall
           midge Haplodiplosis marginata (Diptera: Cecidomyiidae)
    • Authors: Charlotte Rowley; Andrew J Cherrill, Simon R Leather, David R Hall, Tom W Pope
      Pages: 406 - 412
      Abstract: BACKGROUNDThe saddle gall midge, Haplodiplosis marginata (von Roser) (Diptera: Cecidomyiidae), is a pest of cereal crops in Europe. Outbreaks are difficult to predict and effective monitoring tools are required to ensure the effectiveness of pest management options. The female sex pheromone (R)-2-nonyl butyrate provides the basis of a highly effective lure for this insect. Here, we demonstrate how the success of this lure can be influenced by parameters such as trap location, lure age, and interference between traps fitted with these lures.RESULTSA pheromone lure containing (R)-2-nonyl butyrate attracted male midges for at least 9 weeks under field conditions. Pheromone-baited traps performed best when situated away from field margins and below the height of the crop. Interference between nearby traps was evident at distances
      PubDate: 2017-10-16T01:51:15.612537-05:
      DOI: 10.1002/ps.4721
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