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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  [1612 journals]
  • Discovery of metabolic resistance to neonicotinoids in green peach aphids
           (Myzus persicae) in Australia
    • Authors: Siobhan C de Little; Owain Edwards, Anthony R van Rooyen, Andrew Weeks, Paul A Umina
      Abstract: BACKGROUNDMyzus persicae is a serious pest that attacks a broad range of agricultural crops. This species has developed chemical resistance to many insecticides globally and within Australia resistance to multiple chemical groups has been identified. Resistance to neonicotinoid insecticides has been discovered in several countries, but has not previously been confirmed in Australia. We use biomolecular assays and bioassays on field-collected populations to investigate neonicotinoid resistance in M. persicae within Australia.RESULTSSeveral geographically and genetically distinct populations showed evidence for resistance in bioassays. Genetic markers identified the mechanism of neonicotinoid resistance in Australia is metabolic resistance through the enhanced expression of a cytochrome P450 gene, CYP6CY3.CONCLUSIONSM. persicae populations in parts of Australia are now resistant to four different insecticide chemical groups, raising concerns about the long-term management of this pest. While higher copy numbers of CYP6CY3 were seen in all resistant populations, the number of gene copies was not strongly correlated with the level of resistance as determined by LD50 values generated through bioassays. This finding sheds further light on the complexity of the P450 genes at regulating neonicotinoid resistance.
      PubDate: 2016-11-26T06:55:20.916785-05:
      DOI: 10.1002/ps.4495
       
  • Development of a Mechanical Sexing System to Improve the Efficacy of a
           Sterile Insect Area-Wide Release Program to Control American Serpentine
           Leafminer (Diptera: Agromyzidae) in Canadian Ornamental Greenhouses
    • Authors: Maryam Sultan; Rose Buitenhuis, Graeme Murphy, Cynthia D. Scott-Dupree
      Abstract: BACKGROUNDAmerican serpentine leafminer (ASL), Liriomyza trifolii (Burgess), are a significant pest of greenhouse ornamental crops and females damage leaf tissue with their ovipositor during feeding and oviposition. The sterile insect technique has been advocated as a non-chemical alternative to currently available control methods. In area-wide sterile insect release programs, males act as true vectors of sterility. Females should be eliminated from a cohort of pupae prior to irradiation to maximize production economics and sterility spread. The aim of this research was to develop a mechanical sexing system based on pupal size to decrease the proportion of ASL females.RESULTSCumulative frequency distributions were used to examine significant differences in male and female pupal length, dorsal and lateral width distributions. Optimum size cut-off points based on the largest differences in distribution curves were used to determine dimensions of three different sieve designs. Sieve pores measuring 1.543 mm by 0.765 mm excluded 76% of female pupae and doubled the proportion of males in the throughput sample.CONCLUSIONPupal sexual dimorphisms identified in this research can be used to design a sieve to aid in reducing the proportion of females prior to irradiation thus improving the efficacy of an area-wide sterile insect release program.
      PubDate: 2016-11-26T06:50:22.900358-05:
      DOI: 10.1002/ps.4494
       
  • Impact of transgene genome location on gene migration from herbicide
           resistant wheat (Triticum aestivum L.) to jointed goatgrass (Aegilops
           cylindrica Host)
    • Authors: M. Rehman; J.L. Hansen, C.A. Mallory-Smith, R.S. Zemetra
      Abstract: BACKGROUNDWheat (Triticum aestivum) (ABD) and jointed goatgrass (Aegilops cylindrica) (CD) can cross and produce hybrids that can backcross to either parent. Such backcrosses can result in progeny with chromosomes and/or chromosome segments retained from wheat. Thus, a herbicide resistance gene could migrate from wheat to jointed goatgrass. In theory, the risk of gene migration from herbicide resistant-wheat to jointed goatgrass is more likely if the gene is located on the D-genome and less likely if the gene is located on A or B genome of wheat.RESULTSBC1 populations (jointed goatgrass as a recurrent parent) were analyzed for chromosome numbers and transgene transmission rates under sprayed and non-sprayed conditions. Transgene retention in the non-sprayed BC1 generation for the A, B and D genome was 84, 60 and 64%, respectively. In the sprayed populations, the retention was 81, 59, and 74%, respectively.CONCLUSIONThe gene transmission rates were higher than the expected 50% or less under sprayed and non-sprayed conditions possibly due to meiotic chromosome restitution and/or chromosome non-disjunction. Such high transmission rates in the BC1 generation negates the benefits of gene placement for reducing the potential of gene migration from wheat to jointed goatgrass.
      PubDate: 2016-11-25T20:55:24.211328-05:
      DOI: 10.1002/ps.4490
       
  • Field evaluation of 3-hydroxy-2-hexanone and ethanol as attractants for
           the cerambycid beetle pest of vineyards, Xylotrechus arvicola
    • Authors: Álvaro Rodríguez-González; Esteban Sánchez-Maíllo, Horacio J Peláez, Manuel González-Núñez, David R Hall, Pedro A Casquero
      Abstract: BACKGROUNDThe beetle Xylotrechus arvicola (Coleoptera: Cerambycidae) is a serious pest of vineyards in the Iberian Peninsula. In previous work, the male beetles, but not females, were shown to produce (R)-3-hydroxy-2-hexanone, and female beetles were attracted to this compound in a laboratory bioassay. In this study, release rates of 3-hydroxy-2-hexanone from different dispensers were measured in the laboratory and the attractiveness of these to X. arvicola adults determined in trapping tests in three traditional wine-growing regions in Spain.RESULTSAs a result of laboratory experiments, for field experiments 3-hydroxy-2-hexanone was formulated as 100 µl in a polyethylene sachet (50 mm x 50 mm x 250 μ) and ethanol was formulated as 1 ml in a polyethylene press-seal bag (76 mm x 57 mm x 50 μ). Field catches were similar at all three study sites. Catches in traps baited with 3-hydroxy-2-hexanone alone were not significantly different from those in unbaited control traps, but catches in traps baited with 3-hydroxy-2-hexanone and ethanol in separate sachets, with 3-hydroxy-2-hexanone and ethanol in the same sachet, or with ethanol alone, were significantly greater than those in control traps. These results confirm that the beetles are attracted to ethanol and addition of 3-hydroxy-2-hexanone does not seem to make any difference.CONCLUSIONSAttraction of females for the male-produced compound, (R)-3-hydroxy-2-hexanone, has been observed in laboratory but not in field experiments. Traps baited with ethanol are highly attractive to both sexes of adults of X. arvicola, and these can be used for improved monitoring of the adult emergence and for population control by mass trapping.
      PubDate: 2016-11-25T05:05:22.061053-05:
      DOI: 10.1002/ps.4491
       
  • A beekeepers perspective on the neonicotinoid ban.
    • Authors: Norman L Carreck
      Abstract: Bees and agrochemicals have a long history. For example the first volume of IBRA’s journal Bee World in 1919 contains mention of poisoning of bees by spraying an orchard with lead arsenate. Being insects, it is self-evident that the use of insecticides to control crop pests poses a risk to bees. Bee poisoning incidents became a very serious problem in the 1960s and 1970s with spraying of, in particular, oilseed rape with organophosphorus compounds. The introduction of carbamates and then especially synthetic pyrethroids reduced these problems. Data from the Wildlife Incident Investigation Scheme show that in recent years there have been very few poisoning incidents in the UK that can be attributed to agricultural insecticides. The introduction of neonicotinoid insecticides has, however, been very controversial. Almost as soon as they were introduced in the 1990s, French beekeepers blamed colony losses on imidacloprid used on sunflowers and maize, but restrictions on its use did not lead to a reduction in losses or a to a reduction in beekeepers concerns. Acute pesticide poisoning incidents by neonicotinoids in Germany and Italy in 2008 further sealed their reputation. Despite laboratory evidence showing their harm, field experience remains equivocal, and many commercial beekeepers continue to move their colonies to oilseed rape crops for honey production. The neonicotinoid moratorium has undoubtedly led to the increased use of older insecticides, and the effect of this on bee populations is unknown and unquantified. Many beekeepers are currently confused by the conflicting evidence.
      PubDate: 2016-11-25T05:00:34.239698-05:
      DOI: 10.1002/ps.4489
       
  • MicroRNA and dsRNA targeting chitin synthase A reveal a great potential
           for pest management of a hemipteran insect Nilaparvata lugens
    • Authors: Tengchao Li; Jie Chen, Xiaobin Fan, Weiwen Chen, Wenqing Zhang
      Abstract: BACKGROUNDTwo RNA silencing pathways in insects are known to exist that are mediated by short interfering RNAs (siRNAs) and microRNAs (miRNAs), which have been hypothesized to be promising methods for insect pest control. However, a comparison between miRNA and siRNA in pest control is still unavailable, particularly in targeting chitin synthase gene A (CHSA).RESULTSThe dsRNA for Nilaparvata lugens CHSA (dsNlCHSA) and microR-2703 (miR-2703) mimic targeting NlCHSA delivered via feeding affected the development of nymphs, reduced their chitin content and led to lethal phenotypes. The protein level of NlCHSA was downregulated after female adults were injected with dsNlCHSA or the miR-2703 mimic, but there were no significant differences in vitellogenin (NlVg) expression or in total oviposition relative to the control group. However, 90.68% and 46.13% of the eggs laid by the females injected with dsNlCHSA and miR-2703 mimic were unable to hatch, respectively. In addition, a second-generation miRNA and RNAi effect on N. lugens was observed.CONCLUSIONIngested miR-2703 seems to be a good option for killing N. lugens nymphs, while NlCHSA may be a promising target for RNAi-based pest management. These findings provide important evidence for applications of small non-coding RNAs (snRNAs) in insect pest manegement.
      PubDate: 2016-11-25T04:05:48.916817-05:
      DOI: 10.1002/ps.4492
       
  • Design, synthesis and biological evaluation of novel nicotinamide
           derivatives bearing substituted pyrazole moiety as potential SDH
           inhibitors
    • Authors: Xian-Hai Lv; Zi-Li Ren, Peng-liu, Bing-Xin Li, Qing-Shan Li, Ming-Jie Chu, Hai-Qun Cao
      Abstract: BACKGROUNDSuccinate dehydrogenase (SDH) plays an important role in the Krebs cycle, which is considered as an attractive target for development of succinate dehydrogenase inhibitors (SDHIs) based on antifungal agents. Thus, in order to discover novel molecules with high antifungal activities, SDH as target a series of novel nicotinamide derivatives bearing substituted pyrazole moiety were designed and synthesized firstly via a one-pot reaction.RESULTSThe biological assay data showed that compound 3l displayed the most potent antifungal activity with EC50 values of 33.5, 21.4 μM against Helminthosporium maydis and Rhizoctonia cerealis respectively, moreover, 3l exhibited the best inhibitory ability against SDH enzymes. The results of docking simulation showed that 3l was deeply embedded into the SDH binding pocket, and the binding model was stabilized by a cation-π interaction with Arg 43, Tyr 58 and an H-bond with Trp 173.CONCLUSIONIn summary, the study suggests that compound pyrazole nicotinamide derivative 3l may serve as a potential SDHIs which can be used as novel antifungal agent and provide valuable clues for the further design and optimization of SDH inhibitors.
      PubDate: 2016-11-17T03:37:59.398886-05:
      DOI: 10.1002/ps.4488
       
  • Construction, implementation and testing of an image identification system
           using computer vision methods for fruit flies with economic importance
           (Diptera: Tephritidae)
    • Authors: Jiang-ning Wang; Xiao-lin Chen, Xin-wen Hou, Li-bing Zhou, Chao-Dong Zhu, Li-qiang Ji
      Abstract: BACKGROUNDMany species of Tephritidae are damaging to fruit that might negatively impact international fruit trade. Automatic or semi-automatic identification of fruit flies are highly needed for diagnosing causes of damage and quarantine protocols for economically relevant insects.RESULTSA fruit fly image identification system named AFIS1.0 has been developed using 74 species belonging to 6 genera, which include majority pests in Tephritidae. The system combines automated image identification and manual verification, balancing operability and accuracy. AFIS1.0 integrates image analysis and expert system into a content based image retrieval framework. In the automatic identification module, AFIS1.0 gives candidate identification results. Afterwards users can do manually selection based on comparing unidentified images with subset of images corresponding to the automatic identification result. The system uses Gabor surface features in automated identification and yielded an overall classification success rate of 87% to the species level by Independent Multi-part Image Automatic Identification Test.CONCLUSIONThe system is useful for users with or without specific expertise on Tephritidae in the task of rapid and effective identification of fruit flies. It makes the computer vision technology applying to fruit fly's recognition much closer to production level.
      PubDate: 2016-11-17T03:05:50.303324-05:
      DOI: 10.1002/ps.4487
       
  • Mutations in the CYP51 gene reduce DMI sensitivity in Parastagonospora
           nodorum populations in Europe and China
    • Authors: Danilo AS Pereira; Bruce A McDonald, Patrick C Brunner
      Abstract: BACKGROUNDSterol demethylation inhibitors or DMIs have been widely used to manage agronomically important fungal diseases in wheat, but reports of DMI-resistant pathogens continue to mount. Parastagonospora nodorum shows a wide range of sensitivity to DMIs, but until now no molecular mechanisms were identified to explain these differences. The aim of this study was to correlate the DMI sensitivity of a global collection of P. nodorum isolates with mutations in the CYP51 gene that encodes the target of DMI fungicides.RESULTSTwo non-synonymous mutations connected to DMI resistance in other plant pathogenic fungi were detected for the first time in the CYP51 gene of P. nodorum. The two mutations occurred at amino acid position 144, which is homologous to position 137 in other pathogens. The Y144F mutation was detected in China, Denmark, Sweden and Switzerland while the Y144H mutation was found in China and Switzerland. Both mutations were correlated with significantly reduced susceptibility to the DMI fungicide propiconazole.CONCLUSIONCYP51 mutations conferred reduced sensitivity against DMIs in field populations of P. nodorum originating from China, Denmark, Sweden and Switzerland.
      PubDate: 2016-11-14T10:15:25.601657-05:
      DOI: 10.1002/ps.4486
       
  • An entomopathogenic bacterium strain, Bacillus thuringiensis as a
           biological control agent against the red palm weevil, Rhynchophorus
           ferrugineus (Coleoptera: Curculionidae)
    • Authors: Yu-chen Pu; Tian-ling Ma, You-ming Hou, Ming Sun
      Abstract: BACKGROUNDThe red palm weevil (RPW), Rhynchophorus ferrugineus, is an invasive wood-boring insect that damages palms and sugarcane. Bacillus thuringiensis (Bt), is an entomopathogenic bacterium which has been modified into various strains, and widely used in pest management. The aim of this study was to evaluate the susceptibility of RPW to the HA strain of Bt.RESULTSFive concentrations of Bt bioassays were used on RPW eggs, 2nd and 4th instars. Average egg hatching rates exceeded 85% using Bt suspensions or distilled water. Hatch times were extended significantly using higher Bt concentrations. For 2nd instar larvae, the LC50 was 4.92 × 109 CFU/ml 15 d after feeding; the LT50 values decreased with each higher concentration. The corrected mortality of 2nd instars increased significantly with increased concentrations after 15 d, ranging from 16.97% to 94.32%. Significant differences occurred in 4th instars boring activity when dipped in Bt suspensions or crawling on treated sugarcane. Bacterial infection in dead larvae was confirmed using molecular techniques.CONCLUSIONOur results indicated that Bt can be used in RPW control as a potential biological control agent and can effectively reduce palm trees damage.
      PubDate: 2016-11-14T10:05:30.056745-05:
      DOI: 10.1002/ps.4485
       
  • Estimating the development rate of the tomato leaf miner, Tuta absoluta
           (Lepidoptera: Gelechiidae) using linear and non-linear models
    • Authors: Cesar A Marchioro; Flavia S Krechemer, Luis A Foerster
      Abstract: BACKGROUNDTuta absoluta Meyrick (Lepidoptera: Gelechiidae) is native to South America and recently invaded European, African and Asian countries, where it is causing severe damage to tomato crops leading to an increase in the number of insecticide applications. This situation has prompted a demand for alternative pest management strategies aiming to control T. absoluta and concomitantly reduce insecticide applications. The development period for immature stages of T. absoluta at constant temperatures was modelled to select appropriate mathematical functions for simulating its development.RESULTSThe performance of the models varied according to the insect development stage, but in general all models performed well considering the statistical criteria used. Discrimination among models was possible only when the reliability of the temperature thresholds estimated by the models was used as an additional criterion. In this case, the models Briere-1, Lactin-2 and Shi proved adequate to describe the relationship between temperature and development rate of T. absoluta.CONCLUSIONThese models provide an important tool to predict the occurrence of the immature stages of T. absoluta in the field in order to determine the best period for implementing control measures. This is an important contribution to the development of pest management strategies for T.absoluta.
      PubDate: 2016-11-14T10:02:00.822948-05:
      DOI: 10.1002/ps.4484
       
  • Temporal patterns of imidacloprid resistance throughout a growing season
           in Leptinotarsa decemlineata populations
    • Authors: Justin Clements; Sean Schoville, Nathan Clements, Scott Chapman, Russell L. Groves
      Abstract: BACKGROUNDThe Colorado potato beetle, Leptinotarsa decemlineata (Say), is a major agricultural pest of commercial potatoes. Pest managers use a combination of control tactics to limit populations, including multiple insecticides. Finding a window of insecticide susceptibility and understanding genetic responses to insecticide exposure during a growing season may provide novel management recommendations for L. decemlineata.RESULTSWe examined temporal changes (during one growing season) in phenotypic response between a susceptible population and an imidacloprid-resistant population. Beetles remained more susceptible to imidacloprid in the susceptible population throughout the growing season. Estimated mean LC50 values varied throughout the growing season in the resistant population, with increased susceptibility among over-wintered, and recently emerged adult beetles compared with a heightened level of resistance in the second generation. RNA transcript abundance was compared among multiple time points through the growing season, showing that cuticular proteins and cytochrome p450s were highly up-regulated during peaks of measured resistance.CONCLUSIONTemporal variation in imidacloprid susceptibility of L. decemlineata was observed, which included early time points of susceptibility and later peaks in resistance. Heightened resistance occurred during the second generation and correlated to increased transcript abundance of multiple mechanisms of resistance, including multiple cuticular protein and cytochrome p450 transcripts.
      PubDate: 2016-11-11T05:28:07.623844-05:
      DOI: 10.1002/ps.4480
       
  • Dibenzo-α-pyrones: a new class of larvicidal metabolites against Aedes
           aegypti from the endophytic fungus Hyalodendriella sp. Ponipodef12
    • Authors: Ziling Mao; Daowan Lai, Xunda Liu, Xiaoxiang Fu, Jiajia Meng, Ali Wang, Xiaohan Wang, Weibo Sun, Zhi Long Liu, Ligang Zhou, Yang Liu
      Abstract: BACKGROUNDIn our course to find new agrochemicals from endophytic fungi, the crude extract of the endophytic Hyalodendriella sp. Ponipodef12 associated with the hybrid 'Neva' of Populus deltoides Marsh × P. nigra L. was found to possess larvicidal activity against Aedes aegypti.RESULTSFractionation of the extract has led to the isolation of eleven dibenzo-α-pyrones (1–11) including three new congeners, hyalodendriols A-C (1–3). The structures of the new compounds were elucidated by comprehensive spectroscopic analyses, including the modified Mosher's method for the assignment of the absolute configuration. Compounds 2–7 showed potent larvicidal activities against the fourth-instar larvae of A. aegypti with IC50 values ranging from 7.21 to 120.81 µg/mL. Among them, penicilliumolide D (6) displayed the strongest activity (IC50 = 7.21 µg/mL). A structure-larvicidal activity relationship was discussed. The possible mode of action of these compounds was assessed for their acetylcholinesterase inhibitory activities. In addition, hyalodendriol C (3) displayed antibacterial activity against Bacillus subtilis and Xanthomonas vesicatoria, and exhibited strong inhibition against the spore germination of Magnaporthe oryzae.CONCLUSIONOur study revealed dibenzo-α-pyrones to be a new class of larvicidal metabolites against A. aegypti.
      PubDate: 2016-11-11T05:10:31.541947-05:
      DOI: 10.1002/ps.4481
       
  • Effects of foliar and systemic insecticides on whitefly transmission and
           incidence of Cucurbit yellow stunting disorder virus
    • Authors: SJ Castle; John Palumbo, Paul Merten, Charles Cowden, Nilima Prabhaker
      Abstract: BACKGROUNDCucurbit yellow stunting disorder virus (CYSDV) is a cosmopolitan viral disease transmitted by Bemisia tabaci that infects cucurbit crops. Cantaloupe production in the southwestern U.S. has been confronted by epidemics of CYSDV since 2006 when it was first identified in Arizona and California. As a phloem-limited virus that is vectored in a semi-persistent manner by B. tabaci, CYSDV has transmission characteristics that may be suppressed by select insecticide applications.RESULTSEight active ingredients formulated as foliar and/or soil-applied insecticides were tested to determine suppressive effect on transmission and incidence of CYSDV in greenhouse and field studies. Many compounds limited virus transmission to
      PubDate: 2016-11-11T04:45:38.199506-05:
      DOI: 10.1002/ps.4478
       
  • The overexpression of insect endogenous small RNAs in transgenic rice
           inhibits growth and delays pupation of striped stem borer (Chilo
           suppressalis)
    • Authors: Shan Jiang; Hao Wu, Haoju Liu, Jie Zheng, Yongjun Lin, Hao Chen
      Abstract: BACKGROUNDStriped stem borer (Chilo suppressalis Walker, SSB) is a major rice insect pest worldwide. RNA interference (RNAi) has become a promising strategy for developing insect-resistant crops. In a previous study, five double-stranded RNAs (dsRNAs) targeting important SSB housekeeping genes were overexpressed in rice, but none of the acquired dsRNA-transgenic rice plants showed significant effects on SSB.RESULTSThirteen selected SSB endogenous small RNAs, predicted as SSB novel microRNAs (miRNAs), were overexpressed in rice using artificial miRNA (amiRNA) expression technology. Feeding tests showed that two out of 13 selected SSB novel miRNAs caused significant growth inhibition for feeding SSB larvae based on transgenic rice expression. Pupation was delayed 4 d when SSB larvae consecutively fed on transgenic rice expressing the SSB novel miRNA candidate csu-novel-miR15 (csu-15 rice). Gene expression analysis confirmed that the expression levels of at least six SSB unigenes significantly changed (i.e., were up- or down-regulated) after feeding on csu-15 rice.CONCLUSIONSOur research demonstrated a novel RNAi strategy using SSB endogenous small RNAs to develop RNAi crops for pest management; this strategy is different from the common RNAi resulting from transgenic dsRNAs or amiRNAs targeting certain insect endogenous genes.
      PubDate: 2016-11-11T04:45:34.124865-05:
      DOI: 10.1002/ps.4477
       
  • A study of the molluscicidal and larvicidal activities of Citrullus
           colocynthis L. leaf extract and its main cucurbitacins against the mollusc
           Galba truncatula, intermediate host of Fasciola hepatica
    • Authors: Rachid Chawech; Fatma Njeh, Nejia Hamed, Mohamed Damak, Ali Ayadi, Hayet Hammami, Raoudha Mezghani-Jarraya
      Abstract: BACKGROUNDThe molluscicidal and larvicidal activities of the medicinal plant Citrullus colocynthis leaf extracts and its main cucurbitacins were tested against the mollusc gastropod, Galba truncatula, the intermediate host of Fasciola hepatica.RESULTSOur findings proved for the first time that the molluscicidal activity was correlated with the presence of terpenoids. A significant molluscicidal value was found in the ethyl acetate extract (LC50 = 12.6 mg/L). Further fractionation of this extract led to the isolation of two main compounds identified to Cucurbitacin E 1 and 2-O-β-D-glucocucurbitacin E 2. Their molluscicidal activities were also investigated and they possessed close activities with LC50 = 9.55 mg/L and 10.61 mg/L for compounds 2 and 1, respectively.CONCLUSIONThe ethyl acetate extract and both pure compounds proved the highest larvicidal activities with a deterioration rate exceeding 89.2 % (89.2-100%) and with no toxic effects against associated fauna.
      PubDate: 2016-11-11T04:45:25.709234-05:
      DOI: 10.1002/ps.4479
       
  • Preliminary trials of ethanedinitrile (C2N2) fumigation of logs for
           eradication of Bursaphelenchus xylophilus and its vector insect Monochamus
           alternatus
    • Authors: Byung-Ho Lee; Jeong-O Yang, Stephen Beckett, Yonglin Ren
      Abstract: BACKGROUNDThe nematode Bursaphelenchus xylophilus and its insect vectors from the Monochamus genus are major global quarantine pests of timber products. Due to the phaseout of methyl bromide for plant quarantine and pre-shipment treatments, an alternative fumigant is essential. Based on preliminary laboratory studies on the efficacy of ethanedinitrile (C2N2) to B. xylophilus and Monochamus alternatus, three quarantine trials were conducted at three dosages and three temperatures. Potential for inhalation exposure was assessed by monitoring atmospheric C2N2 in relation to the threshold limit value.RESULTSConcentration × time products (Ct) of 398.6, 547.2 and 595.9 g h m−3 were obtained for each trial. A100% mortality of B. xylophilus and M. alternatus larvae at 23 ± 4 °C and 10 ± 4 °C occurred with a load factor of pine logs of 46% and at 3 ± 1 °C with a load factor of 30%. During all fumigations, atmospheric levels of C2N2 20 m downwind were below the TLV. During aeration, levels 10 m and 5 m downwind were below the TLV after 0.4 h and 1 h, respectively.CONCLUSIONFor the purpose of quarantine or phytosanitary treatment, specific doses of C2N2 at the trial temperatures could control B. xylophilus and M. alternatus larvae without significant inhalation risk to workers.
      PubDate: 2016-11-09T15:25:41.678883-05:
      DOI: 10.1002/ps.4476
       
  • Economic injury levels and sequential sampling plans for Frankliniella
           schultzei in watermelon crops
    • Authors: Poliana S Pereira; Renato A Sarmento, Tarcísio V S Galdino, Carlos H O Lima, Fábio A dos Santos, Joedna Silva, Gil R dos Santos, Marcelo C Picanço
      Abstract: BACKGROUNDThe thrips Frankliniella schultzei is an important watermelon pest. Nevertheless, economic injury levels and sampling plans for this pest have not yet been determined for this crop. Thus, the objective of the present study was to determine the economic injury levels and develop sequential sampling plans for F. schultzei in conditions of low, medium, and high fruit prices.RESULTSThe attack of F. schultzei on watermelon plants during the vegetative stage reduced the crop's productivity, which did not happen in the flowering and fruiting stage. The economic injury levels were 0.09, 0.04, and 0.02 thrips per leaf when the watermelon price was low (US$ 62.5/t), medium (US$ 140.63/t), and high (US$ 218.75/t), respectively. The three sequential sampling plans for F. schultzei generated for the economic injury levels resulted in similar and more rapid decisions compared to the conventional plan, especially when the pest density was high.CONCLUSIONSThe three economic injury levels and the sequential sampling plans generated in the present study can be incorporated into integrated pest management programs for watermelon crops because these plans provide a rapid and adequate control decision for F. schultzei.
      PubDate: 2016-11-09T15:22:47.632912-05:
      DOI: 10.1002/ps.4475
       
  • Using Calendula officinalis as a floral resource to enhance aphid and
           thrips suppression by the flower bug Orius sauteri (Hemiptera:
           Anthocoridae)
    • Authors: Jing Zhao; Xiaojun Guo, Xiaoling Tan, Nicolas Desneux, Lucia Zappala, Fan Zhang, Su Wang
      Abstract: BACKGROUNDThe flower bug Orius sauteri (Poppius) (Hemiptera: Anthocoridae) is widely used as a biocontrol agent against thrips and aphids infesting greenhouse vegetables in Asia. The survival and oviposition of such predators, as well as biocontrol services they provided, may be enhanced by adding extra floral resources to the crops. In the current study, we investigated the effects of the plant Calendula officinalis L., used as a floral resources, for promoting the control of Myzus persicae (Sulzer) and Frankliniella occidentalis (Pergande) by O. sauteri under laboratory and greenhouse conditions.RESULTSResults showed that the presence of C. officinalis enhanced aphid and thrips suppression via an increased O. sauteri population growth. The predator populations responded positively to the addition of C. officinalis in the system and they varied also as function of the temperatures tested under laboratory conditions. In a similar way, predator populations varied among seasons with the highest densities recorded in May in greenhouse.CONCLUSIONC. officinalis can be used to increase available resources for natural enemies used in agricultural crops, notably in greenhouses. This study also provides evidence that increasing floral resources can enhance pest suppression provided by O. sauteri.
      PubDate: 2016-11-08T22:23:43.191728-05:
      DOI: 10.1002/ps.4474
       
  • Mismatch repair deficiency increases the transfer of antibiosis and
           antixenosis properties against Colorado potato beetle in somatic hybrids
           of Solanum tuberosum (+) S. chacoense
    • Authors: Imola Molnár; Enikő Besenyei, Ramona Thieme, Thomas Thieme, Adriana Aurori, Andreea Baricz, Horia Leonard Banciu, Elena Rakosy-Tican
      Abstract: BACKGROUNDColorado potato beetle (CPB) has become the biggest enemy of cultivated potato worldwide. One of the most effective sources of resistance to CPB is Solanum chacoense, an accession with a high leptine glycoalkaloid content. The aim of our study was to assay the repellence and toxicity of S. chacoense, its somatic hybrids (SHs) and their backcross progenies (BC1) with potato for CPB adults and larvae. Transgenic S. chacoense, deficient in DNA mismatch repair (MMR) was also used to produce SHs, in order to increase homeologous recombination and hence introgression of wild species DNA into the potato genepool.RESULTSWild type SH was highly resistant to CPB. Resistance to CPB of BC1 progenies showed 1:3 inheritance pattern. MMR-deficient SHs performed better in the resistance analysis. Most of MMR-deficient SHs had a similar toxicity as S. chacoense and intensely repellent effect on CPB adults. Resistance of SHs and BC1 clones may be attributed to leptine biosynthesis, which was confirmed using a RAPD marker.CONCLUSIONThis is the first report of SHs and their progenies exhibiting both antibiosis and antixenosis against CPB. Resistant SHs are an important step forward in combating this voracious pest of potato.
      PubDate: 2016-11-08T21:50:12.940604-05:
      DOI: 10.1002/ps.4473
       
  • RNA interference of an antimicrobial peptide, Btdef, reduces Tomato yellow
           leaf curl China virus accumulation in the whitefly Bemisia tabaci
    • Authors: Zhi-zhi Wang; Xiao-li Bing, Shu-sheng Liu, Xue-xin Chen
      Abstract: BackgroundThe whitefly Bemisia tabaci (Gennadius) is considered as one of the main pests for agriculture. One important problem with the whitefly is its notorious status as a vector for plant viruses, primarily begomoviruses. We have previously identified a defensin-like antimicrobial peptide, Btdef, from the whitefly B. tabaci MEAM1. However, the function of Btdef in the immune system of the insect vector and begomovirus transmission has yet to be explored.ResultsTo explore the role of Btdef during begomovirus transmission, we firstly investigated the transcriptional response of Btdef following acquisition of Tomato yellow leaf curl China virus (TYLCCNV). The expression of Btdef was up-regulated in the viruliferous whiteflies. After RNA silencing of the Btdef gene in adult whiteflies fed with dsRNA, they were allowed to feed on TYLCCNV-infected plants and then quantified for TYLCCNV DNA titer. Unexpectedly, silencing the Btdef gene reduced both the abundance and expressions of TYLCCNV genes in the whiteflies. In the meantime, the density of the endosymbiont Rickettsia was significantly reduced in dsBtdef-fed whiteflies.ConclusionOur data provide evidence that Btdef is involved in begomovirus infection, possibly through symbiont-mediated alteration of begomovirus-whitefly interactions. These findings indicate that Btdef may be targeted for the development of new technology for the control of whitefly-transmitted begomoviruses.
      PubDate: 2016-11-02T02:46:50.974241-05:
      DOI: 10.1002/ps.4472
       
  • Enhanced photosynthesis endows seedling growth vigor contributing to the
           competitive dominance of weedy rice over cultivated rice
    • Authors: Lei Dai; Xiaoling Song, Baoye He, Bernal E. Valverde, Sheng Qiang
      Abstract: BACKGROUNDWeedy rice, as one of the worst paddy field weeds worldwide, bears vigorous seedlings and dominantly competes with cultivated rice causing serious crop yield losses. To elucidate the causes of its stronger seedling vigor endowing its dominant competition with cultivated rice, comparative studies on seedling growth characteristics were conducted among six weedy rice biotypes and the two indica and japonica cultivars Shanyou-63 (SY-63) and Zhendao-8 (ZD-8), respectively, in the greenhouse.RESULTSWeedy rice emerged two to three days earlier, rapidly grew 1.3-1.7 cm taller daily, produced more secondary adventitious roots and greater aboveground fresh biomass than cultivated rice. Moreover, weedy rice exhibited greater photosynthetic pigment content, net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, and chlorophyll fluorescence kinetic parameters. An enhanced overall photosynthetic activity in weedy rices was attributed to the combined action of a larger antenna, more active reaction centers and higher quantum yield for electron transfer beyond QA.CONCLUSIONSEnhanced photosynthesis of weedy rice at the seedling stage should be the main factor for leading to strong competitive dominance over cultivated rice.
      PubDate: 2016-10-28T00:00:22.428344-05:
      DOI: 10.1002/ps.4471
       
  • Resistance evolution in Drosophila: the case of CYP6G1
    • Authors: Gaelle Le Goff; Frédérique Hilliou
      Abstract: The massive use of DDT as insecticide between 1940 and 1970 has resulted in the emergence of resistant population of insects. One of the main metabolic mechanisms developed by resistant insects involves detoxification enzymes such as cytochrome P450s. These enzymes can metabolize the insecticide to render it less toxic and facilitate its elimination from the organism. The P450 Cyp6g1 was identified as the major factor responsible for DDT resistance in Drosophila melanogaster field populations. In this article, we review the data available for this gene since it was associated with resistance in 2002. The knowledge gained on Cyp6g1 allows a better understanding of the evolution of insecticide resistance mechanisms and highlights the major role of transposable elements in evolutionary processes.
      PubDate: 2016-10-27T07:30:44.878788-05:
      DOI: 10.1002/ps.4470
       
  • Overexpression of UDP- glycosyltransferase gene UGT2B17 is involved in
           chlorantraniliprole resistance in Plutella xylostella (L.)
    • Authors: Xiuxia Li; Bin Zhu, Xiwu Gao, Pei Liang
      Abstract: BACKGROUNDUDP-glycosyltransferases (UGTs) are phase II detoxification enzymes widely distributed within living organisms. Their involvement in the biotransformation of various lipophilic endogenous compounds and phytoalexins in insects has been documented. However, the roles of this enzyme family in insecticide resistance have rarely been reported. Here, the functions of UGTs in chlorantraniliprole resistance in Plutella xylostella were investigated.RESULTSTreatment with sulfinpyrazone and 5-nitrouracil (both inhibitors of UGT enzymes) significantly increased the toxicity of chlorantraniliprole against the third instar larvae of P. xylostella. Among the 23 UGT transcripts examined, only UGT2B17 was found to be overexpressed (with a range from 30.7- to 77.3-fold) in all four chlorantraniliprole-resistant populations compared to the susceptible one (CHS). The knock-down of UGT2B17 by RNA interference (RNAi) dramatically increased the toxicity of chlorantraniliprole by 27.4% and 29.8% in the CHS and CHR (resistant) populations, respectively. In contrast, exposure to phenobarbital significantly increased the relative expression of UGT2B17 while decreasing the toxicity of chlorantraniliprole to the larvae by 14.0%.CONCLUSIONUGT2B17 is involved in the detoxification of chlorantraniliprole, and its overexpression may play an important role in chlorantraniliprole resistance in P. xylostella. These results shed some light upon and further our understanding of the mechanisms of diamide insecticide resistance in insects.
      PubDate: 2016-10-27T07:20:22.346686-05:
      DOI: 10.1002/ps.4469
       
  • Phosphine resistance does not confer cross resistance to sulfuryl fluoride
           in four major stored grain insect pests
    • Authors: Rajeswaran Jagadeesan; Manoj K Nayak
      Abstract: BACKGROUNDSusceptibility to phosphine (PH3) and sulfuryl fluoride (SF) and cross resistance to SF were evaluated in two life stages (eggs and adults) of key grain insect pests, Rhyzopertha dominca (F.), Sitophilus oryzae (L.), Cryptolestes ferrugineus (Stephens), and Tribolium castaneum (Herbst). This study was performed with an aim to integrate SF into phosphine resistance management program in Australia.RESULTSCharacterisation of susceptibility and resistance to phosphine in eggs and adults showed that C. ferrugineus was the most tolerant as well as resistant species. Mortality responses of eggs and adults to SF at 25 °C revealed T. castaneum to be the most tolerant species followed by S. oryzae, C. ferrugineus and R. dominica. A high dose range of SF, 50.8–62.2 mg L−1 over 48 h, representing a c (concentration) x t (time) products of 2438–2985 gh m−3 was required for complete control of eggs of T. castaneum, whereas eggs of the least tolerant R. dominca required only 630 gh m−3 for 48 h (13.13 mg L−1). Mortality response of eggs and adults of phosphine-resistant strain to SF in all four species confirmed the lack of cross resistance to SF.CONCLUSIONOur research concludes that phosphine resistance does not confer cross resistance to SF in grain insect pests irrespective of the variation in levels of tolerance to SF itself or resistance to phosphine in their egg and adult stages. While our study confirms that SF has potentials as a “phosphine resistance breaker”, the observed higher tolerance in eggs stresses the importance of developing SF fumigation protocols with longer exposure periods.
      PubDate: 2016-10-26T08:56:23.019093-05:
      DOI: 10.1002/ps.4468
       
  • A glycoprotein α-amylase inhibitor from Withania somnifera differentially
           inhibits various α-amylases and affects growth and development of
           Tribolium castaneum
    • Authors: Sainath S. Kasar; Kiran R. Marathe, Amey J. Bhide, Abhijeet P. Herwade, Ashok P. Giri, Vijay L. Maheshwari, Pankaj K. Pawar
      Abstract: BACKGROUNDIdentification and characterization of plant defensive molecules enrich our resources to design crop protection strategies. In particular, plant derived proteinaceous inhibitor(s) ofinsect digestive enzymes appear to be a safe, sustainable and attractive option.RESULTSA glycoprotein having non-competitive α-amylase inhibitory activity with molecular weight 8.3 kDa was isolated and purified from seeds of Withania somnifera (WSAI). Its mass spectrometry analysis revealed 59% sequence coverage with Wrightide II type α-AI from Wrightia religiosa. A dose dependent inhibition of α-amylases from Aspergillus oryzae, Bacillus subtilis, Helicoverpa armigera and Tribolium castaneum was recorded. Interestingly, WSAI did not inhibit human salivary α-amylase significantly. When adults of T. castaneum were fed with WSAI (1.6 mg/g), decrease in consumption, growth and efficiency of conversion of ingested food were evident along with over 4-fold elevations in feeding deterrence index. A decline in larval residual α-amylase activity after feeding of WSAI resulted into reduction of longevity of T. castaneum.CONCLUSIONStudy reflects significance of WSAI to affect the overall growth and development of T. castaneum. Pre and post-harvest pest resistive capability makes WSAI a potential candidate for insect pest management. Further, effectiveness of this inhibitor could be explored either in formulations or through transgenic approach.
      PubDate: 2016-10-22T00:35:22.234722-05:
      DOI: 10.1002/ps.4467
       
  • Synthesis and Biological Activity of Pyridazine Amides, Hydrazones and
           Hydrazides
    • Authors: Ann M. Buysse; Maurice C. H. Yap, Ricky Hunter, Jonathan Babcock, Xinpei Huang, Marshall H. Parker
      Abstract: BACKGROUNDOptimization studies on compounds initially designed to be herbicides led to the discovery of a series of [6-(3-pyridyl)pyridazin-3-yl]amides exhibiting aphicidal properties. Systematic modifications of the amide moiety as well as the pyridine and pyridazine rings were carried out to determine if these changes could improve insecticidal potency.RESULTSStructure-activity relationship (SAR) studies showed that changes to the pyridine and pyridazine rings generally resulted in a significant loss of insecticidal potency against green peach aphids (Myzus persicae (Sulzer) and cotton aphids (Aphis gossypii (Glover). However, replacement of the amide moiety with hydrazines, hydrazones, or hydrazides appeared to be tolerated, with small aliphatic substituents being especially potent.CONCLUSIONSA series of aphicidal [6-(3-pyridyl)pyridazin-3-yl]amides were discovered as a result of random screening of compounds that were intially investigated as herbicides. Follow-up studies of the structure activity relationship of these [6-(3-pyridyl)pyridazin-3-yl]amides showed that biosteric replacement of the amide moiety was widely tolerated suggesting that further opportunities for exploitation may exsist for this new area of insecticidal chemistry. Insecticidal efficacy from the original hit, compound 1, to the efficacy of compound 14 produced greater than 10-fold potency improvement against Aphis gossypii and greater than 14-fold potency improvement against Myzus persicae.
      PubDate: 2016-10-21T02:30:36.075486-05:
      DOI: 10.1002/ps.4465
       
  • Comparison of ingestion and topical application of insecticides against
           the common bed bug, Cimex lectularius (Hemiptera: Cimicidae)
    • Authors: Angela Sierras; Coby Schal
      Abstract: BACKGROUNDThe global prevalence of Cimex lectularius infestations has challenged current intervention efforts, as pyrethroid resistance has become ubiquitous, availability of labeled insecticides for bed bugs is limited, and non-chemical treatment options, such as heat, are often unaffordable. We evaluated representative insecticides toward the goal of developing a novel, ingestible liquid bait for hematophagous arthropods.RESULTSLC50 values were estimated for adult males and first instar nymphs of an insecticide-susceptible strain for abamectin, clothianidin, fipronil and indoxacarb, after ingestion from an in vitro feeder. LD50 values were calculated based on the ingested blood volume. Ingested abamectin, clothianidin and fipronil caused rapid mortality in both life stages. Fipronil was ~43-fold more effective by ingestion than by topical application. Indoxacarb and its bioactive metabolite decarbomethoxyllated JW062 (DCJW) were ineffective at causing bed bug mortality even at concentrations as high as 1000 ng mL−1 blood.CONCLUSIONSFipronil, clothianidin and abamectin have potential for being incorporated into a liquid bait for bed bug control; indoxacarb and DCJW were not effective. Bed bugs are a good candidate for an ingestible liquid bait because systemic formulations generally require less active ingredient than residual sprays, they remain contained and more effectively target hematophagous arthropods.
      PubDate: 2016-10-21T02:00:38.522087-05:
      DOI: 10.1002/ps.4464
       
  • Reduced Absorption of Glyphosate and Decreased Translocation of Dicamba
           Contribute to Poor Control of Kochia (Kochia scoparia) at High Temperature
           
    • Authors: Junjun Ou; Phillip W. Stahlman, Mithila Jugulam
      Abstract: BACKGROUNDPlant growth temperature is one of the important factors that can influence postemergent herbicide efficacy and impact weed control. Control of kochia (Kochia scoparia), a major broadleaf weed throughout the North American Great Plains, often is unsatisfactory when either glyphosate or dicamba are applied on hot summer days. We tested effects of plant growth temperature on glyphosate and dicamba phytotoxicity on two Kansas kochia populations (P1 and P2) grown under the following three day/night (d/n) temperature regimes: T1, 17.5/7.5 °C; T2, 25/15 °C; and T3, 32.5/22.5 °C.RESULTSVisual injury and above-ground dry biomass data from herbicide dose response experiments indicated greater susceptibility to both glyphosate and dicamba when kochia was grown under the two cooler temperature regimes, i.e. T1 and T2. At T1, the ED50 of P1 and P2 kochia were 39 and 36 g · ha−1 of glyphosate and 52 and 105 g · ha -1 of dicamba, respectively. In comparison, at T3 the ED50 increased to 173 and 186 g · ha−1 for glyphosate and 106 and 410 g · ha−1 for dicamba, respectively, for P1 and P2. We also investigated the physiological basis of decreased glyphosate and dicamba efficacy under elevated temperatures. Kochia absorbed more glyphosate at T1 and T2 compared to T3. Conversely, there was more dicamba translocated towards meristems at T1 and T2, compared to T3.CONCLUSIONReduced efficacy of dicamba or glyphosate to control kochia under elevated temperatures can be attributed to decreased absorption and translocation of glyphosate and dicamba, respectively. Therefore, it is recommended to apply glyphosate or dicamba when the temperature is low (e.g. d/n temperature at 25/15 °C) and seedlings are small (less than 12 cm) to maximize kochia control.
      PubDate: 2016-10-21T01:35:22.642003-05:
      DOI: 10.1002/ps.4463
       
  • The Rise and Future of Glyphosate and Glyphosate-Resistant Crops
    • Authors: Jerry M. Green
      Abstract: Glyphosate and glyphosate-resistant crops had a revolutionary impact on weed management practices, but the epidemic of glyphosate-resistant (GR) weeds is rapidly decreasing the value of these technologies. In areas that fully adopted glyphosate and GR crops, GR weeds evolved and glyphosate and glyphosate traits now must be combined with other technologies. The chemical company solution is to combine glyphosate with other chemicals, and the seed company solution is to combine glyphosate resistance with other traits. Unfortunately, companies have not discovered a new commercial herbicide mode-of-action for over 30 years and have already developed or are developing traits for all existing herbicide types with high utility. Glyphosate mixtures and glyphosate trait combinations will be the mainstays of weed management for many growers, but are not going to be enough to keep up with the capacity of weeds to evolve resistance. Glufosinate, auxin, HPPD-inhibiting and other herbicide traits, even when combined with glyphosate resistance, are incremental and temporary solutions. Herbicide and seed businesses are not going to be able to support what critics call the chemical and transgenic treadmills for much longer. The long time without the discovery of a new herbicide mode-of-action and the epidemic of resistant weeds is forcing many growers to spend much more to manage weeds and creating a worst of times, best of times predicament for the crop protection and seed industry.
      PubDate: 2016-10-18T22:55:21.423423-05:
      DOI: 10.1002/ps.4462
       
  • Perspectives on the Agrochemical Industry and Agrochemical Discovery
    • Authors: Thomas C Sparks; Beth A Lorsbach
      Abstract: Agrochemicals have been critical to the production of food and fiber, as well as the control of vectors of disease. The need for the discovery and development of new agrochemicals continues unabated due to the loss of existing products through the development of resistance, the desire for products with more favorable environmental and toxicological profiles, shifting pest spectrums, and changing agricultural needs and practices. As presented in the associated analysis of the agrochemical industry, the rising costs and complexities of agrochemical discovery has, in part, led to increasing consolidation, especially in the US and Europe. However, as demonstrated by the present analysis, the discovery of new agrochemicals continues in spite of the challenges.
      PubDate: 2016-10-18T01:56:01.893395-05:
      DOI: 10.1002/ps.4457
       
  • A PERSPECTIVE ON MANAGEMENT OF HELICOVERPA ARMIGERA: TRANSGENIC BT COTTON,
           IPM, AND LANDSCAPES
    • Authors: Sharon Downes; Darren Kriticos, Hazel Parry, Cate Paull, Nancy Schellhorn, Myron P. Zalucki
      Abstract: Helicoverpa armigera is a major pest of agriculture, horticulture and floriculture throughout the old world and recently invaded parts of the new world.We overview of the evolution in thinking about the application of area-wide approaches to assist with its control by the Australian Cotton Industry to highlight important lessons and future challenges to achieving the same in the New World. An over-reliance of broad-spectrum insecticides led to Helicoverpa spp. in Australian cotton rapidly became resistant to DDT, synthetic pyrethroids, organophosphates, carbamates and endosulfan. Voluntary strategies were developed to slow the development of insecticide resistance, which included rotating chemistries and basing spray decisions on thresholds. Despite adoption of these practices, insecticide resistance continued to develop until the introduction of genetically modified cotton provided a platform for augmenting Integrated Pest Management in the Australian cotton industry. Compliance with mandatory resistance management plans for Bt cotton necessitated a shift from pest control at the level of individual fields or farms towards a coordinated area-wide landscape approach. Our take home message for control of H. armigera is that resistance management is essential in genetically modified crops and must be season long and area-wide to be effective.
      PubDate: 2016-10-17T23:00:21.904865-05:
      DOI: 10.1002/ps.4461
       
  • Computational Design of Novel Inhibitors to Overcome Weed Resistance
           Associated with Acetohydroxyacid Synthase (AHAS) P197L Mutant
    • Authors: Ren-Yu Qu; Jing-Fang Yang, Yu-Chao Liu, Qiong Chen, Ge-Fei Hao, Cong-Wei Niu, Zhen Xi, Guang-Fu Yang
      Abstract: BACKGOUNDAcetohydroxyacid synthase (AHAS; EC 2.2.1.6) is the first common enzyme in the biosynthetic pathway leading to the branched-chain amino acids in plants and a wide range of microorganisms. With the long-term and wide application of AHAS inhibitors, weed resistance is becoming a global problem, which leads to an urgent demand for novel inhibitors to antagonize both wild-type and resistant AHAS.RESULTSPyrimidinyl-Salicylic acid derivatives, as one of the main classes of commercial AHAS herbicides, show potential anti-resistant bioactivity to wild-type and P197L mutant. In current work, a series of novel 2-benzoyloxy- 6-pyrimidinyl salicylic acid derivatives were designed through fragment-based drug discovery (FBDD). Fortunately, the newly synthesized compounds showed a good inhibitory activity against both wild-type and P197L mutant. Some compounds not only had a lower resistance factor value, but also showed an excellent inhibitory activity against wild type AHAS and P197L mutant. Furthermore greenhouse experiments showed compound 11 m displayed almost 100% inhibition against both wild-type and high-resistant Descurainia sophia at the dosage of 150 g.ai/ha.CONCLUSIONThe present work indicated that the 2-benzoyloxy- 6-pyrimidinyl salicylic acid motif was well worth further optimization. And compound 11 m can be used as a potential anti-resistant AHAS herbicide which requires further research.
      PubDate: 2016-10-17T03:06:15.66104-05:0
      DOI: 10.1002/ps.4460
       
  • Natural Products, Their Derivatives, Mimics and Synthetic Equivalents:
           Role in Agrochemical Discovery
    • Authors: Thomas C. Sparks; Donald R. Hahn, Negar V. Garizi
      Abstract: Natural products (NPs) have a long history as a source of, and inspiration for, novel agrochemcials. Many of the existing herbicides, fungicides and insecticides have their origins in a wide range of NPs from a variety of sources. Due to the changing needs of agriculture, shifts in pest spectrum, development of resistance and evolving regulatory requirements, the need for new agrochemical tools remains as critical as ever. As such, NPs continue to be an important source of models and templates for the development of new agrochemicals, demonstrated by the fact that NP models exist for many of the pest control agents that were discovered by other means. Interestingly, there appear to be distinct differences in the success of different NP sources for different pesticide uses. While a few microbial NPs have been important starting points in recent discoveries of some insecticidal agrochemicals, historically plant sources have contributed the most to the discovery of new insecticides. In contrast, fungi have been the most important NP sources for new fungicides. Like insecticides, plant sourced NPs have made the largest contribution to herbicide discovery. Available data on 2014 global sales and numbers of compounds in each class of pesticides indicate that the overall impact of NPs to the discovery of herbicides has been relatively modest compared to impact observed for fungicides and insecticides. However, as new sourcing and approaches to NP discovery evolve, the impact of NPs in all agrochemical arenas will continue to expand.
      PubDate: 2016-10-14T00:40:24.9129-05:00
      DOI: 10.1002/ps.4458
       
  • Spider (Araneae) Predations on White-Backed Planthopper Sogatella
           furcifera in Subtropical Rice Ecosystems, China
    • Authors: Xue-Qin Wang; Guang-Hua Wang, Zeng-Rong Zhu, Qi-Yi Tang, Yang Hu, Fei Qiao, Kong Luen Heong, Jia-an Cheng
      Abstract: BACKGROUNDSpiders are effective biological control agents in rice ecosystems, but the comparative study of predations among main spider species under field conditions have not been fully explored since lack of practical methodology. In this study, more than 6000 spiders of dominant species were collected from subtropical rice ecosystems to compare their predations on Sogatella furcifera (Horváth) using DNA based gut content analysis.RESULTSThe positive rates for all spider taxa were closely related to prey densities, as well as their behaviors and niches. The relationships of positive rates to prey planthopper densities for Pardosa pseudoannulata (Böes.et Str.), Coleosoma octomaculata (Böes.et Str.), Tetragnatha maxillosa Thorell and Ummeliata insecticeps (Böes.et Str.) in field conditions could be described with saturated response curves. Quantitative comparisons of predations among the 4 spider species confirmed that P. pseudoannulata and C. octomaculata were more rapacious than U. insecticeps and T. maxillosa in field conditions. The comparison of ratio of spider to WBPH and positive rates between fields revealed that biological control by spiders could be effectively integrated with variety resistance.CONCLUSIONThe generalist spiders could follow up WBPH population in time and assemblages of spiders cooperated with variety resistance could effectively suppress WBPH population.
      PubDate: 2016-10-14T00:06:06.016243-05:
      DOI: 10.1002/ps.4459
       
  • Use of an individual-based simulation model to explore and evaluate
           potential insecticide resistance management strategies
    • Authors: Russell Slater; Pierre Stratonovitch, Jan Elias, Mikhail A. Semenov, Ian Denholm
      Abstract: BACKGROUNDTools with the potential to predict risks of insecticide resistance and aid the evaluation and design of resistance management tactics are of value to all sectors of the pest management community. Here we describe use of a versatile individual-based model of resistance evolution to simulate how strategies employing single and multiple insecticides influence resistance development in the pollen beetle, Meligethes aeneus.RESULTSUnder repeated exposure to a single insecticide, resistance evolved faster to a pyrethroid (lambda-cyhalothrin) than to a pyridine azomethane (pymetrozine), due to difference in initial efficacy. A mixture of these compounds delayed resistance compared to use of single products. The effectiveness of rotations depended on the sequence in which compounds were applied in response to pest density thresholds. Effectiveness of a mixture strategy declined with reductions in grower compliance. At least 50% compliance was needed to cause some delay in resistance development.CONCLUSIONNo single strategy meets all requirements for managing resistance. It is important to evaluate factors that prevail under particular pest management scenarios. The model used here provides operators with a valuable means for evaluating and extending sound resistance management advice, as well as understanding needs and opportunities offered by new control techniques.
      PubDate: 2016-10-12T20:50:28.250307-05:
      DOI: 10.1002/ps.4456
       
  • Comparative metabolomics analysis of Callosobruchus chinensis larvae under
           hypoxia, hypoxia/hypercapnia and normoxia
    • Authors: Sufen Cui; Lei Wang, Jiangping Qiu, Zhicheng Liu, Xueqing Geng
      Abstract: BACKGOUNDThe tolerance to low oxygen (hypoxia) and high carbon dioxide (hypercapnia) is criticalfor insect control. On the basis of bioassay, metabolism profiles were built to dissect adaptive mechanism in bean weevil under hypoxia, hypoxia/hypercapnia, and normoxia usinggas chromatography–time-of-flight mass spectrometry (GC–TOF–MS).RESULTThe growth and development of bean weevils were suppressed significantly by two hypoxia situations, and hypercapnia enhanced the mortality, but after 24-d exposure, the surviving insects emerged adults earlier than those under hypoxia only. Metabolism profiles also showed striking difference in metabolites among three groups, both quantitatively and qualitatively. A total of 61 metabolites changed significantly in three pairs of comparison, among them, 40 were in hypoxia and 37 in hypoxia/hypercapnia relative to control groups, 16 metabolites were found between two treatments. Increased metabolites were mainly carbohydrates, amino acids and organic acids, while free fatty acids were decreased. Furthermore, the changes were further strengthened by the addition of hypercapnia, but excluding free fatty acids.CONCLUTIONOur findings showed bean weevil has high tolerance to hypoxia, even hypoxia/hypercapnia at biologically achievable levels and provides more direct evidence for stored-product insect mechanism regulation under hypoxia stress, especially free fatty acid regulation by hypercapnia, but not hypoxia.
      PubDate: 2016-10-08T08:20:46.92898-05:0
      DOI: 10.1002/ps.4455
       
  • Detecting pyrethroid resistance in predatory mites inhabiting soil and
           litter: An in vitro test
    • Authors: Marine El Adouzi; Olivier Bonato, Lise Roy
      Abstract: BACKGROUNDWhile resistance against insecticides is widely known in pest arthropods, it remains poorly known in non-target arthropods of the same agrosystems. This may be of crucial importance in the context of organic pest management or IPM: first, stopping of pesticide pressure during farm conversion may lead to important rearrangements of non-target communities due to fitness cost of resistance in populations of some species. Second, resistant biological agents may be useful to farms with low synthetic pesticide use. Communities of mesostigmatid mites, encompassing numerous predatory species, are supposed to be involved in important ecological processes in both crop soils and animal litter/manure.RESULTSHere we provide a tarsal-contact method for assessing resistance in different populations from various species of mesostigmatid mites. Analyses of data from repeated tests on three populations from different mesostigmatid families proved the method to be robust and able to generate consistent and reliable mortality percentages according to insecticide concentration.CONCLUSIONOur bioassay system allows for both one-shot estimate of pyrethroid sensitivity in mite populations and estimation of how it changes over time, making possible survival analyses and assessment of recovery from knockdown. The rating system retained makes it possible to score response to insecticides in a consistent and standard way in species from different mesostigmatid families.
      PubDate: 2016-10-08T08:10:22.892811-05:
      DOI: 10.1002/ps.4454
       
  • Combined use of Bacillus subtilis strain B-001 and bactericide for the
           control of tomato bacterial wilt
    • Authors: Di Peng; Kun Luo, Huidan Jiang, Yanan Deng, Lianyang Bai, Xiaomao Zhou
      Abstract: BACKGROUNDTomato bacterial wilt caused by Ralstonia solanacearum poses a serious threat to tomato production. However, no effective control measures are available. In this study, we combined the bactericide Saisentong with an effective biological control agent Bacillus subtilis B-001 to control tomato bacterial wilt under greenhouse and field conditions.RESULTSGrowth of B-001 in vitro was unaffected by Saisentong. In greenhouse experiments, the combined application of B-001and Saisentong via root irrigation or spray resulted in better disease control compared with either agent alone. In two fieldtrials, at a concentration of 400 to 500 mg kg−1 Saisentong, the combination treatment was more effective than expected and showed a synergistic effect. A lower concentration of Saisentong (200 or 300 mg kg−1) in combination with B-001 resulted in antagonistic effect. However, disease control was significantly greater compared with either treatment alone.CONCLUSIONThe combination of Saisentong and B-001 effectively controls tomato bacterial wilt. The integrated strategy represents a promising new tool to control the disease.
      PubDate: 2016-10-08T04:00:42.513302-05:
      DOI: 10.1002/ps.4453
       
  • Evaluation of systemic neonicotinoid insecticides for the management of
           the Asian citrus psyllid Diaphorina citri on containerized citrus
    • Authors: Frank J. Byrne; Matthew P. Daugherty, Elizabeth E. Grafton-Cardwell, James A. Bethke, Joseph G. Morse
      Abstract: BACKGROUNDStudies were conducted to evaluate uptake and retention of 3 systemic neonicotinoid insecticides, dinotefuran, imidacloprid, and thiamethoxam, in potted citrus nursery plants treated at standard label rates. Infestation of these plants placed at a field site with moderate levels of Asian citrus psyllid (ACP) was monitored for 14 weeks following treatments and insecticide residues in leaf tissue were quantified using ELISA. Bioassays were conducted using leaves harvested on various dates post-treatment to compare the efficacies of residues against adult ACP.RESULTSResidues of the 3 neonicotinoids were detected in leaf tissues within 1 week after treatment. Peak concentrations established at 1 week for imidacloprid and dinotefuran and at 2 weeks for thiamethoxam. Imidacloprid and thiamethoxam outperformed the control and dinotefuran treatments at protecting trees from infestations by ACP eggs and nymphs. For a given insecticide concentration in leaf tissue, thiamethoxam induced the highest mortality of the 3 insecticides, and dinotefuran was the least toxic.CONCLUSIONIf the time needed to achieve effective thresholds of a systemic neonicotinoid is known, treatments at production facilities could be scheduled that would minimize unnecessary post-treatment holding periods and ensure maximum retention of effective concentrations after the plants have shipped to retail outlets. The rapid uptake of the insecticides and retention at effective concentrations in containerized citrus suggest that the current 30-day post-treatment shipping restriction from production facilities to retail outlets outside of quarantine could be shortened to 14 days. Thiamethoxam should be added to the list of approved nursery treatments.
      PubDate: 2016-10-07T02:30:47.953007-05:
      DOI: 10.1002/ps.4451
       
  • Insecticide Resistance, Control Failure Likelihood, & the First Law of
           Geography
    • Authors: Raul Narciso C Guedes
      Abstract: Insecticide resistance is a broadly recognized ecological backlash resulting from insecticide use and is widely reported among arthropod pest species with well-recognized underlying mechanisms and consequences. Nonetheless, insecticide resistance is the subject of evolving conceptual views that introduces a different concept useful if recognized in its own right—the risk or likelihood of control failure. Here we suggest an experimental approach to assess the likelihood of control failure of an insecticide allowing for consistent decision-making regarding management of insecticide resistance. We also challenge the current emphasis on limited spatial sampling of arthropod populations for resistance diagnosis in favor of comprehensive spatial sampling. This necessarily requires larger population sampling—aiming to use spatial analysis in area-wide surveys—to recognize focal points of insecticide resistance and/or control failure that will better direct management efforts. The continuous geographical scale of such surveys will depend on the arthropod pest species, pattern of insecticide use, and many other potential factors. Regardless, distance-dependence among sampling sites should still hold, following the maxim that the closer two things are, the more they resemble each other, which is the basis of Tobler's First Law of Geography.
      PubDate: 2016-10-07T02:11:26.837899-05:
      DOI: 10.1002/ps.4452
       
  • Sensitivity of Fusarium culmorum to triazoles: impact of trichothecene
           chemotypes, oxidative stress response and genetic diversity
    • Authors: Pierre Hellin; Jonathan Scauflaire, Viviane Van Hese, Françoise Munaut, Anne Legrève
      Abstract: BACKGROUNDFusarium culmorum is a fungal pathogen occurring worldwide on various weeds and important crops. Triazoles have been shown to be the most effective fungicide for managing Fusarium spp. but little is known about their specific activity on F. culmorum.RESULTSThe sensitivity of 107 F. culmorum strains to triazoles was assessed using microtiter plate assays. The EC50 values ranged from 0.14 to 1.53 mg L −1 for tebuconazole and from 0.25 to 2.47 mg L −1 for epoxiconazole. High cross-resistance to both azoles was found (r = 0.61). Fusarium culmorum appeared to be significantly more sensitive than F. graminearum or F. cerealis. No increase in the mean EC50 was observed over time, which might be related to an unfavorable fitness cost, measured here as fungal growth. On average, nivalenol-producing strains of F. culmorum were significantly more resistant than deoxynivalenol-producing strains. The relationship between resistance and chemotype-dependent adaptation to oxidative stress was investigated, but remained unclear. No link between inter-simple sequence repeat (ISSR) genetic diversity and triazole resistance could be established.CONCLUSIONFungicide use might not be a driving force in the evolution of F. culmorum and the benefit of a resistance trait probably does not outweigh its costs.
      PubDate: 2016-10-03T10:55:30.801352-05:
      DOI: 10.1002/ps.4450
       
  • Synergistic mortality between a neonicotinoid insecticide and an
           ergosterol-biosynthesis-inhibiting fungicide in three bee species
    • Authors: Fabio Sgolastra; Piotr Medrzycki, Laura Bortolotti, Maria Teresa Renzi, Simone Tosi, Gherardo Bogo, Dariusz Teper, Claudio Porrini, Roberto Molowny-Horas, Jordi Bosch
      Abstract: BACKGROUNDNeonicotinoid insecticides have been identified as an important factor contributing to bee diversity declines. Nonetheless, uncertainties remain about their impact under field conditions. Most studies have been conducted on Apis mellifera and tested single compounds. However, in agricultural environments, bees are often exposed to multiple pesticides. We explore synergistic mortality between a neonicotinoid (clothianidin) and an ergosterol-biosynthesis-inhibitor fungicide (propiconazole) in three bee species (A. mellifera, Bombus terrestris, Osmia bicornis) following oral exposure in the laboratory.RESULTSWe developed a new approach based on the binomial proportion test to analyze synergistic interactions. We estimated uptake of clothianidin per foraging bout in honey bees foraging on seed-coated rapeseed fields. We found significant synergistic mortality in all three bee species exposed to non-lethal doses of propiconazole and their respective LD10 of clothianidin. Significant synergism was only found in the first assessment times in A. mellifera (4 and 24 h) and B. terrestris (4 h), but persisted throughout the experiment (96 h) in O. bicornis. Osmia bicornis was also the most sensitive species to clothianidin.CONCLUSIONOur results underscore the importance to test pesticide combinations likely to occur in agricultural environments, and to include several bee species in environmental risk assessment schemes.
      PubDate: 2016-09-29T10:16:27.217387-05:
      DOI: 10.1002/ps.4449
       
  • Establishment of in vitro soybean aphids, Aphis glycines (Hemiptera:
           Aphididae): a tool to facilitate studies of aphid symbionts, plant-insect
           interactions and insecticide efficacy
    • Authors: Andika Gunadi; Raman Bansal, John J Finer, Andy Michel
      Abstract: BACKGROUNDStudies on plant-insect interactions of the soybean aphid, Aphis glycines (Matsumura), can be influenced by environmental fluctuations, status of the host plant and variability in microbial populations. Maintenance of aphids on in vitro-grown plants minimizes environmental fluctuations, provides uniform host materials and permits the selective elimination of aphid-associated microbes for more standardized controls in aphid research.RESULTSAphids were reared on sterile, in vitro-grown soybean seedlings, germinated on plant tissue culture media amended with a mixture of antimicrobials. For initiation and maintenance of in vitro aphid colonies, single aphids were inoculated onto single in vitro seedlings. After 3 rounds of transfer of “clean” aphids to fresh in vitro seedlings, contamination was no longer observed, and aphids performed equally well when compared to those reared on detached leaves. Addition of the insecticides thiamethoxam and chlorantraniliprole to the culture medium confirmed uptake and caused significant mortality to the in vitro aphids. The use of the antimicrobial mixture removed the associated bacteria Arsenophonus but retained Buchnera and Wolbachia within the in vitro aphids.CONCLUSIONThe in vitro aphid system is a novel and highly useful tool to understand insecticidal efficacy and expand our knowledge of tri-trophic interactions among plants, insects and symbionts.
      PubDate: 2016-09-28T09:03:17.002205-05:
      DOI: 10.1002/ps.4448
       
  • No effect of Bt-transgenic rice litter on meiobenthos community in field
           ditches
    • Authors: Yongbo Liu; Wanxiang Jiang, Yuyong Liang, Caiyun Zhao, Junsheng Li
      Abstract: BACKGROUNDThe non-target effect of Bacillus thuringiensis (Bt) toxins in aquatic ecosystems is crucial to improve the present assessment of Bt-transgenic plants, particularly where crops are cultivated near aquatic ecosystems. We conducted decomposition experiments during two growing seasons to determine the effects of Bacillus thuringiensis (Bt)-transgenic rice litter with and without insecticide application on meiobenthos communities in a field ditch.RESULTSCommunity composition of meiobenthos colonized on leaf litter was not significantly different between Bt and non-Bt rice. Abundance of meiobenthos colonizing leaves differed between insecticide application and control, and this insecticide effect was interacted with rice type. No Bt toxin was detected in the field ditch water. Leaf decomposition and nutrient content were comparable for both Bt and non-Bt rice with or without insecticide application.CONCLUSIONBt-transgenic rice litter had no effect on meiobenthos community composition in field ditches, but the chronic persistence of transgenic litter in nature needs to be taken into account at large scales in aquatic ecosystems.
      PubDate: 2016-09-22T08:40:22.76349-05:0
      DOI: 10.1002/ps.4446
       
  • Biological control potential of entomopathogenic nematodes for management
           of Caribbean fruit fly, Anastrepha suspensa Loew (Tephritidae)
    • Authors: William K. Heve; Fahiem E. El‐Borai, Daniel Carrillo, Larry W. Duncan
      Abstract: BACKGROUNDCaribbean fruit fly (Caribfly) is a serious economic insect pest because of development of larvae that hatch from eggs oviposited into fruits by female adults. This study assessed virulence of at least 10 entomopathogenic nematodes (EPNs) to Caribfly in laboratory bioassays as a starting point toward evaluation of management strategies for the fruit‐to‐soil‐dwelling stages of A. suspensa in fields infested by Caribfly.RESULTSInoculation of A. suspensa with 1 ml of ca. 200 IJs (larva)−1 killed Caribfly at either larval or pupal stage. Pupae were more resistant to EPN infections than larvae. Adult emergence from inoculated pupae in soil microcosms was significantly lower than those observed in filter paper assays. Longest or largest steinernematids suppressed emergence of more adult Caribfly from pupae in soils whereas shorter heterorhabditids were more infectious to Caribfly larvae. The highest mortalities of A. suspensa were caused by exotic nematodes Steinernema feltiae and Heterorhabditis bacteriophora followed by the native Heterorhabditis indica and the exotic Steinernema carpocapsae.CONCLUSIONEntomopathogenic nematodes reduced development of Caribfly larvae and pupae to adult in our bioassays, suggesting that EPNs have potential for biological control of A. suspensa. Future work will assess management strategies, using the virulent EPNs, in orchards infested by A. suspensa.
      PubDate: 2016-09-22T08:35:22.025783-05:
      DOI: 10.1002/ps.4447
       
  • Molecular characterization of two α‐esterase genes involving
           chlorpyrifos detoxification in the diamondback moth, Plutella xylostella
    • Authors: Miao Xie; Na‐Na Ren, Yan‐Chun You, Wei‐Jun Chen, Qi‐Sheng Song, Min‐Sheng You
      Abstract: BACKGROUNDCarboxylesterases (CarEs) are involved in metabolic detoxification of dietary and environmental xenobiotics in insects. However, due to the complexity of the protein family, the involvement of CarEs in insecticide metabolism in Plutella xylostella has not been fully elucidated. This study aimed to characterize two CarE genes and assess their potential roles in response to chlorpyrifos in P. xylostella.RESULTSSynergistic test showed that triphenyl phosphate decreased the resistance of the 3rd‐instar larvae to chlorpyrifos. The treatment of the 3rd‐instar larvae with chlorpyrifos at the dose of LC30 led to significant increase of CarE activity. Two CarE cDNAs (Pxae18 and Pxae28) were subsequently sequenced and characterized. Both genes were expressed predominantly in larva midgut. Most importantly, two CarE genes showed significantly higher expression in the chlorpyrifos resistant strain (CRS) than in the susceptible strain (SS). RNAi knockdown of Pxae18 and Pxae28 significantly increased the mortality to chlorpyrifos from 40% in control to 73.8% and 63.3%, respectively.CONCLUSIONRNAi knockdown of Pxae18 and Pxae28 significantly inhibited the detoxification ability, and increased the mortality in P. xylostella. The results indicate that these two CarE genes play important roles in detoxification of chlorpyrifos in P. xylostella.
      PubDate: 2016-09-22T08:31:15.471615-05:
      DOI: 10.1002/ps.4445
       
  • A potential IGR for cockroach control: design, synthesis and bioactivity
           of N‐terminal modified allatostatin analogs
    • Authors: Xiaoqing Wu; Meizi Wang, Juan Huang, Li Zhang, Zhe Zhang, Yun Ling, Xinling Yang, Stephen S. Tobe
      Abstract: BACKGROUNDThe FGLa‐allatostatins (ASTs) are a family of neuropeptides that can inhibit juvenile hormone biosynthesis by the corpora allata (CA) in vitro, and therefore, they are regarded as insect growth regulator (IGR) candidates for pest control. In our previous studies, an AST mimic, H17 was found to have a significant effect on JH biosynthesis by cockroach CA, both in vitro and in vivo. To discover new potential mimics and explore the substituent effect on the inhibition of JH biosynthesis, 30 analogs, modified with various substituents on the benzene ring at the N‐terminus of lead compound H17, were designed and synthesized. Their bioactivity in inhibiting JH biosynthesis by the CA of Diploptera punctata and the potency of M9, M10 and M11 in activation of Dippu‐AstR was evaluated.RESULTSAll the analogs showed an effect on JH biosynthesis by CA in vitro. M9, M10 and M11 can activate the Dippu‐AstR, albeit with much lower potency than that of AST 1. M11 also exhibited improved in vitro activity (IC50: 6.98 nmol/L) in comparison with the lead compound H17 (IC50: 29.5 nmol/L). In particular, M11 displayed good in vivo activity in inhibiting JH biosynthesis and basal oocyte growth.CONCLUSIONThe structure‐activity relationship (SAR) studies suggest that different positions of substituents on the benzene ring of the cinnamic acid can lead to different activities. The para‐substitution on the benzene ring plays an important role in inhibiting JH biosynthesis in vitro. Moreover, M11 is considered to be a potential IGR for cockroach control.
      PubDate: 2016-09-22T08:31:06.964895-05:
      DOI: 10.1002/ps.4444
       
  • Characterisation of Ramularia collo‐cygni laboratory mutants resistant
           to Succinate Dehydrogenase Inhibitors
    • Authors: Marta J Piotrowska; James M Fountaine, Richard A Ennos, Maciej Kaczmarek, Fiona J Burnett
      Abstract: BACKGROUNDRamularia collo‐cygni (Rcc) is responsible for Ramularia leaf spot (RLS), a foliar disease of barley contributing to serious economic losses. Protection against the disease has been almost exclusively based on fungicide applications, including Succinate Dehydrogenase Inhibitors (SDHIs). In 2015 the first field isolates of Rcc with reduced sensitivity to SDHIs were recorded in some European countries. In this study we established baseline sensitivity of Rcc to SDHIs in the UK and characterised mutations correlating with resistance to SDHIs in UV‐generated mutants.RESULTSFive SDHI resistant isolates were generated by UV mutagenesis. In four of these mutants a single amino acid change in a target succinate dehydrogenase (Sdh) protein was associated with decrease in sensitivity to SDHIs. Three of these mutations were stably inherited in the absence of SDHI fungicide and resistant isolates did not demonstrate a fitness penalty. There were no detectable declines in sensitivity in field populations in years 2010–2012 in the UK.CONCLUSIONSSDHIs remained effective in controlling Rcc in the UK in years 2010–2012. However given that the first isolates of Rcc with reduced sensitivity appeared in other European countries in 2015, robust anti‐resistance strategies need to be continuously implemented to maintain effective disease control.
      PubDate: 2016-09-19T09:50:32.905348-05:
      DOI: 10.1002/ps.4442
       
  • Overexpression of TAT‐PTD‐diapause hormone fusion protein in tobacco
           and it effect on larval development of Helicoverpa armigera (Lepidoptera:
           Noctuidae)
    • Authors: Zhou Zhou; Yongli Li, Chunyan Yuan, Daniel Doucet, Yongan Zhang, Liangjian Qu
      Abstract: BACKGROUNDThe diapause hormone (DH) has been shown to either induce or terminate diapause depending on the insect species. In a previous study we demonstrated that the DH from Clostera anastomosis (caDH) has biological activity in Helicoverpa armigera, which prompted us to examine the potential growth‐inhibiting or antiherbivory effects of the TAT‐caDH fusion protein when expressed in transgenic plants.RESULTSIn this study, we produced transgenic tobacco plants expressing either the TAT‐caDH protein, or a TAT‐caDH‐eGFP fusion version that allows tracking of the fluorescent protein in plant tissues. Our results indicate that H. armigera larvae feeding on transgenic tobacco expressing TAT‐caDH exhibited a significantly reduced survival rate and weight gain. However, larvae feeding on transgenic tobacco expressing TAT‐caDH‐eGFP were unaffected. While fusion of the eGFP gene influenced the bioactivity of caDH in larvae, TAT‐caDH‐eGFP can still penetrate the insect midgut cell membrane.CONCLUSIONTAT‐caDH increases DH stability in oral delivery. Our results may help in targeting DH‐dependent physiological processes in insects for improving herbivore tolerance in economically important crops.
      PubDate: 2016-09-19T09:40:20.718787-05:
      DOI: 10.1002/ps.4443
       
  • Phorate can reverse P450 metabolism‐based herbicide resistance in
           Lolium rigidum
    • Authors: Roberto Busi; Todd Adam Gaines, Stephen Powles
      Abstract: BACKGROUNDOrgano‐phosphate insecticides can inhibit specific cytochrome P450 enzymes involved in metabolic herbicide resistance mechanisms leading to synergistic interactions between the insecticide and the herbicide. In this study we report synergistic versus antagonistic interactions between the organo‐phosphate insecticide phorate and five different herbicides observed in a population of multiple herbicide‐resistant Lolium rigidum.RESULTSPhorate synergized with three different herbicide modes of action enhancing the activity of the ALS‐inhibitor chlorsulfuron (60% LD50 reduction), the VLCFAE‐inhibitor pyroxasulfone (40% LD50 reduction), and the mitosis‐inhibitor trifluralin (70% LD50 reduction). Conversely, phorate antagonized the two thiocarbamate herbicides prosulfocarb (7‐fold LD50 increase) and triallate (11‐fold LD50 increase).CONCLUSIONWe report the selective reversal of P450‐mediated metabolic multiple‐resistance to chlorsulfuron and trifluralin in the grass weed L. rigidum by synergistic interaction with the insecticide phorate and discuss the putative mechanistic basis. This research should encourage diversity in herbicide use patterns for weed control as part of a long‐term integrated management effort to reduce the risk of selection of metabolism‐based multiple herbicide resistance in L. rigidum.
      PubDate: 2016-09-19T09:35:22.019313-05:
      DOI: 10.1002/ps.4441
       
  • Substitutions in Spodoptera exigua Topoisomerase I modulate its relaxation
           activity and camptothecin sensitivity
    • Authors: Pei Zhang; Lan Zhang, Yanning Zhang, Liangang Mao, Hongyun Jiang
      Abstract: BACKGROUNDTopoisomerase I (Top I) is referred as the cellular target of the camptothecins (CPTs) which are now being explored as potential pesticides for insect control. Three amino acid substitutions including L530P, A653T and S729T in Top Is of insects were found in our previous studies. In order to investigate the effect of these three substitutions, the comparative analysis was conducted between the wild type and mutant Top Is in Spodoptera exigua Hübner.RESULTSThe optimal salt concentration of A653T and S729T was 150 mM consistent with that of the wild type Top I. While, the mutant L530P showed the maximum relaxation activity at a lower KCl concentration (100 mM). The mutated L530P and A653T Top Is showed higher relaxation efficiency due to the increased relaxation velocity toward the negatively supercoiled plasmid pBR322 DNA, which rendered L530P and A653T resistance to CPTs. While, mutant S729T exhibited sensitivity to CPTs as a result of a decreased relaxation activity toward plasmid pBR322 DNA.CONCLUSIONSThese results suggested that the polymorphism in Top I of insects was related to the biological activity of CPTs, which provided the basic information for the reasonable usage of CPTs to control insect pests.
      PubDate: 2016-09-19T09:29:40.022106-05:
      DOI: 10.1002/ps.4440
       
  • Inhibition of early development stages of rust fungi by the two fungal
           metabolites cyclopaldic acid and epi‐epoformin
    • Authors: Eleonora Barilli; Alessio Cimmino, Marco Masi, Marco Evidente, Diego Rubiales, Antonio Evidente
      Abstract: BACKGROUNDRusts are a noxious group of plant diseases affecting major economically important crops. Crop protection is largely based on chemical control. There is a renewed interest in the discovery of natural products as alternatives to synthetic fungicides for control. In this study we tested two fungal metabolites, namely cyclopaldic acid and epi‐epoformin, for their effectiveness in reducing early stages of development of two major rusts fungi from the genera Puccinia and Uromyces, P. triticina and U. pisi. Spore germination and appressoria formation were assessed on pre‐treated detached leaves under controlled conditions. Cyclopaldic acid and epi‐epofomin were also tested in infected plants in order to evaluate the level of control achieved by treatments both before and after inoculation.RESULTSCyclopaldic acid and epi‐epoformin were strongly effective in inhibiting fungal germination and penetration of both rust species studied. This effect was not dose‐dependent. These results were further confirmed in planta by spraying the metabolites on plants leaves which reduced fungal developmental of U. pisi and P. triticina at values comparable to those obtained by application of the fungicide.CONCLUSIONOur results further demonstrate the potential of fungal metabolites as natural alternatives to synthetic fungicides for the control of crop pathogens of economic importance as rusts.
      PubDate: 2016-09-14T04:05:42.680358-05:
      DOI: 10.1002/ps.4438
       
  • Insecticide resistance and size assortative mating in females of the maize
           weevil (Sitophilus zeamais)
    • Authors: Erick Mauricio G Cordeiro; Alberto S Corrêa, Conrado A Rosi‐Denadai, Hudson Vaner V Tomé, Raul Narciso C Guedes
      Abstract: BACKGROUNDRandom mating is a common assumption in studies of insecticide resistance evolution, but seldom tested despite its potential consequences. Therefore, the existing evidence of female choice and insecticide resistance in populations of the maize weevil (Sitophilus zeamais), a key pest of stored cereals, led to the assessment of mating preferences and its association with insecticide resistance in this species.RESULTSMixed lines of a maize weevil colony were established from field‐collected populations, which after five months of natural breeding were selected for deltamethrin resistance for five generations reaching over 100‐fold resistance. Mating preference was significantly based on the partner size, measured as body mass (χ2 = 5.83, df = 1, P = 0.016). Susceptible females preferred heavier males for mating (χ2 = 5.83, df = 1, P = 0.015), trait that was more frequently associated with deltamethrin resistance (χ2 = 7.38, df = 1, P = 0.007). Deltamethrin resistance compromised daily fertility, although the reduced offspring production observed in matings between susceptible females and resistant males were negligible.CONCLUSIONSusceptible female weevils prefer larger (and heavier) males to mate, trait associated with deltamethrin resistance, favoring the maintenance and spread of the resistant phenotype in the population.
      PubDate: 2016-09-14T03:55:31.426955-05:
      DOI: 10.1002/ps.4437
       
  • Monitoring and mechanisms of insecticide resistance in Chilo suppressalis
           (Lepidoptera: Crambidae) with special reference to diamides
    • Authors: Rong Yao; Dan‐Dan Zhao, Shuai Zhang, Li‐Qi Zhou, Xin Wang, Cong‐Fen Gao, Shun‐Fan Wu
      Abstract: BACKGROUNDThe rice stem borer, Chilo suppressalis Walker (Lepidoptera: Crambidae) is one of the most economically important pests of rice in Asia. Chemical control remains the most efficient primary means for controlling this pest.RESULTSSignificant variations among field populations to seven insecticides were observed. The populations exhibited LC50 values that ranged between 0.605 ‐ 108.088 mg a.i L−1 for chlorantraniliprole and 0.046 ‐ 3.919 mg a.i L−1 for flubendiamide. YY14 population collected from Yuyao in Zhejiang province at 2014 showed moderate resistance level to two diamides, i.e., up to 77.6‐ and 42.6‐fold for chlorantraniliprole and flubendiamide, respectively. Synergism tests and biochemical assays showed no obvious correlations between diamides resistance and three detoxifying enzymes. Sequence comparison of ryanodine receptor gene between YY14 resistant population and susceptible population revealed that a glycine to glutamic acid substitution (G4910E) was presented in the YY14 population.CONCLUSIONG4910E mutation might be involved in the resistance evolution of C. suppressalis to the diamides. The appropriate insecticide resistance management program should be established to maintain the effectiveness of the insecticides and to ensure sustainable management.
      PubDate: 2016-09-14T03:47:18.459542-05:
      DOI: 10.1002/ps.4439
       
  • A negative association between bromadiolone exposure and nestling body
           condition in common kestrels: management implications for vole outbreaks
    • Authors: J. Martínez‐Padilla; D. López‐Idiáquez, J.J. López‐Perea, R. Mateo, A. Paz, J. Viñuela
      Abstract: BACKGROUNDVole outbreaks have been extensively described along with their impacts on humans, particularly in agricultural areas. The use of rodenticides is a common legal practice to minimise crop damage induced by high vole density for biocidal use. However, rodenticides can have negative direct and indirect impacts on non‐target species that feed on voles. We studied whether the use of a second generation anticoagulant rodenticide, bromadiolone, can be detected in the blood of fledglings of wild common kestrels Falco tinnunculus in two areas of central Spain, exploring its possible indirect effects.RESULTSWe found that 16.9% of fledgling had detectable concentration of bromadiolone in their blood, with an average concentration of 0.248 ± 0.023 ng/mL. Fledglings with bromadiolone in their blood, regardless of the concentration, had 6.7% lower body mass than those without detectable bromadiolone.CONCLUSIONThe use of bromadiolone was detectable in the blood of alive non‐target species. Detected bromadiolone in blood may reduce body condition of nestlings, potentially reducing their fitness. The source of bromadiolone found in nestlings need to be determined in future studies to derive accurate management advice. However, we urge the discontinuation of official SGAR distribution to farmers and their use in agrarian lands to minimise damage of voles on crops, particularly where common kestrel breed and encourage the use of alternative effective practices.
      PubDate: 2016-09-12T04:55:28.009228-05:
      DOI: 10.1002/ps.4435
       
  • Detection of the cytochrome b mutation G143A in Irish Rhynchosporium
           commune populations using targeted 454 sequencing
    • Authors: Sinead Phelan; Marie‐Sophie Barthe, Camille Tobie, Steven Kildea
      Abstract: BACKGROUNDRhynchosporium commune is a major fungal pathogen of barley crops and the application of fungicides, such as Quinone outside inhibitors (QoI’s), plays an important role in crop disease control. The genetic mechanisms linked to QoI resistance have been identified in the cytochrome b gene, with QoI resistance conferred by the G143A substitution. The objective of this study was to develop a high throughput molecular assay to detect and identify mutations associated with QoI resistance within the Irish R. commune population.RESULTSLeaf lesions of R. commune sampled from 74 sites, during 2009‐2014, and isolates from 2006 and 2007 were screened for non‐synonymous mutations of the cytochrome b gene using 454 targeted sequencing. The presence of the G143A substitution was confirmed in R. commune samples in one site in 2013 and in four sites in 2014, however the frequency of the substitution in these samples was low (2‐18%). 454 sequencing results were confirmed though PCR‐RFLP and Sanger sequencing.CONCLUSIONThe molecular assay which has been applied to this monitoring programme has shown that the application of 454 next generation sequencing offers the potential for high throughput and accurate characterisation of non‐synonymous mutations associated with fungicide resistance in a crop pathogen.
      PubDate: 2016-09-12T04:06:08.607765-05:
      DOI: 10.1002/ps.4434
       
  • ELECTROSTATIC SPRAYING IN THE CHEMICAL CONTROL OF Triozoida limbata
           (ENDERLEIN) (HEMIPTERA: TRIOZIDAE) IN GUAVA TREES (Psidium guajava L.)
    • Authors: Rafael M Tavares; João P A R Cunha, Thales C Alves, Mariana R Bueno, Sérgio M Silva, César H S Zandonadi
      Abstract: BACKGROUNDDue to the difficulty in reaching targets during pesticide applications on guava trees, it is important to evaluate new technologies that may improve pest management. In electrostatic spraying, an electric force is added to the droplets to control their movements such that they are efficiently directed to the target. The present study evaluated the performance of electrostatic and non‐electrostatic spraying in the control of the guava psyllid, the deposition of the spray mixture on the leaves, and the losses to the soil.RESULTSThe deposition of the spray mixture was up to two times greater when using electrostatic spraying in comparison with non‐electrostatic application. The losses of the spray mixture to the soil were up to four times smaller with the electrostatic spraying. Electrostatic had better control of the psyllid.CONCLUSIONIt was possible to reduce the volume rate of application with electrostatic spraying without adversely affecting the control of the guava psyllid.
      PubDate: 2016-09-08T08:45:45.603231-05:
      DOI: 10.1002/ps.4433
       
  • Active saponins from root of Pueraria peduncularis (Grah. ex Benth.)
           Benth. and their molluscicidal effects on Pomacea canaliculata
    • Authors: ChunPing Yang; Min Zhang, Bo Lei, GuoShu Gong, GuiZhou Yue, XiaoLi Chang, XiaoFang Sun, Yue Tian, HuaBao Chen
      Abstract: BACKGROUNDPueraria peduncularis (Grah. ex Benth.) Benth., which belongs to the Leguminosae family, exhibits resistance to many crop pests in agricultural production. Pomacea canaliculata is an important invasive snail in rice fields and causes severe yield losses. To evaluate the toxicity of P. peduncularis to P. canaliculata, in this study, the molluscicidal activity of root extracts of P. peduncularis was tested against P. canaliculata, and the active compounds were isolated, and the structures of these compounds were analyzed on the basis of using nuclear magnetic resonance (NMR) analysis and mass spectral analysis.RESULTSOur results showed that the molluscicidal activity of the root crude extract differed between P. canaliculata with different shell diameters after treatment for 72 h. The median lethal concentration (LC50) was 5.511 mg · L−1 against snails with1.5 ± 0.2 cm in diameter and 12.383 mg · L−1 against snails with 2.5 ± 0.2 cm in diameter. Furthermore, two active ingredients isolated from root methanol extracts were identified as pedunsaponin A and pedunsaponin C. Both pedunsaponin A and C showed strong molluscicidal activities, with LC50 values of 3.893 mg · L−1 and 4.252 mg · L−1, respectively, against snails with shell diameters of 1.5 ± 0.2 cm after treatment for 72 h.CONCLUSIONPueraria peduncularis extracts exhibit high molluscicidal activity and have great potential value for exploring a molluscicide to control Pomacea canaliculata.
      PubDate: 2016-09-08T08:45:42.622886-05:
      DOI: 10.1002/ps.4432
       
  • Discovery of the aryl heterocyclic amine (AHA) insecticides: Synthesis,
           insecticidal activity, field results, mode of action and bioavailability
           of a leading field candidate
    • Authors: William H Dent; Mark A Pobanz, Chaoxian Geng, Thomas C Sparks, Gerald B Watson, Theodore J Letherer, Kenneth W Beavers, Cathy D Young, Yelena A Adelfinskaya, Ronald R Ross, Greg Whiteker, James Renga
      Abstract: BACKGROUNDGamma‐amino butyric acid (GABA) antagonists are proven targets for control of Lepidopteran and other pests. New heterocyclic compounds with high insecticidal activity were discovered using a competitive‐intelligence inspired scaffold hopping approach to generate analogs of fipronil, a known GABA antagonist. These novel aryl heterocyclic amines (AHA’s) displayed broad spectrum activity on a number of chewing insect pests.RESULTSThrough >370 modifications of the core AHA structure, a 7‐pyrazolopyridine lead molecule was found to exhibit much improved activity on a number of insect pests. In field trial studies, its performance was 2 – 4x lower than commercial standards and also appeared to be species dependent with good activity seen for larvae of Spodoptera exigua, but inactive on larvae of Trichoplusia ni.CONCLUSIONAn extensive investigational biology effort demonstrated that these AHA analogs appear to have multiple modes of action including GABA receptor antagonism and mitopotential or uncoupler activity. The limited capability in larvae of T. ni to convert the lead molecule to its associated open form correlates with the low toxicity of the lead molecule in this species. This work has provided information that could aid investigations of novel GABA antagonists.
      PubDate: 2016-09-08T08:25:19.649081-05:
      DOI: 10.1002/ps.4431
       
  • Biological activity of Myrtaceae plant essential oils and their major
           components against Drosophila suzukii (Diptera: Drosophilidae)
    • Authors: Miyeon Jang; Junheon Kim, Kyungjae Andrew Yoon, Si Hyeock Lee, Chung Gyoo Park
      Abstract: BackgroundThe spotted wing drosophila (SWD), Drosophila suzukii (Matsumura), is a globally invasive and serious pest of numerous soft‐skinned fruit crops. Assessments were made of fumigant and contact toxicities of 12 Myrtaceae plant essential oils (EOs) and their components. For determining the mode of action of major components of active EOs, their activities against acetylcholinesterase (AChE) and Glutathione S‐transferase (GST) were also assessed.ResultsStrong fumigant and contact toxicities were observed from EOs of Eucalyptus citriodora and Melaleuca teretifolia. The main components of E. citriodora were citronellal and isopulegol, whereas those of M. teretifolia were neral and geranial. Geranial showed the strongest fumigant activity followed by citronellal or neral, M. teretifolia EO, isopulegol, and E. citriodora EO. In contact toxicity assay, Geranial also exhibited the strongest insecticidal activity followed by neral or M. teretifolia EO, citronellol, citronellal, isopulegol, and E. citriodora EO. Among the major components, all compounds showed low AChE inhibitory activity, while neral and geranial showed GST inhibitory activity against SWD.ConclusionMyrtaceae plant EOs and their components have an excellent potential for being used in the control of SWD adult and could be useful in the development of more effective natural compounds as alternatives to synthetic pesticides.
      PubDate: 2016-09-08T07:35:41.348074-05:
      DOI: 10.1002/ps.4430
       
  • Impact of sesquiterpenes from Inula racemosa (Asteraceae) on growth,
           development and nutrition of Spodoptera litura (Lepidoptera:Noctuidae)
    • Authors: Mandeep Kaur; Rakesh Kumar, Deep Patel Upendrabhai, Inder Pal Singh, Sanehdeep Kaur
      Abstract: BACKGROUNDThe use of botanical pesticides for protecting crops from insect pests has assumed greater importance all over the world due to growing awareness of harmful effects of indiscriminate use of synthetic pesticides. Inula racemosa Hook. f. (Asteraceae), a medicinally important perennial herb is rich in sesquiterpenes with many biological activities. The present studies were conducted with the objective to evaluate the sesquiterpenes isolated from I. racemosa for insecticidal activity against Spodoptera litura (F.).RESULTSAlantolactone and isoalantolactone isolated from I. racemosa, exerted growth inhibitory effects on S. litura. Addition of both the sesquiterpenes to larval diet extended the development period and reduced pupation as well as adult emergence. The dietary utilization experiments on 3rd instar larvae of S. litura revealed reduction in consumption and growth rates of larvae as well as efficiency of conversion of ingested and digested food due to alantolactone and isoalantolactone.CONCLUSIONThe root extract of I. racemosa which is rich in two sesquiterpenes i.e. alantolactone and isoalantolactone, has the potential for management of S. litura. However, there is need to understand the specific mechanism of action of these compounds.
      PubDate: 2016-09-08T07:31:16.575324-05:
      DOI: 10.1002/ps.4429
       
  • Evaluating a filtering and recirculating system to reduce dust drift in
           simulated sowing of dressed seed and abraded dust particle characteristics
           
    • Authors: Marcello Biocca; Daniele Pochi, Roberto Fanigliulo, Pietro Gallo, Patrizio Pulcini, Francesca Marcovecchio, Cinzia Perrino
      Abstract: BACKGROUNDThe pneumatic precision drills used in maize sowing can release dust due to abrasion of dressed seed; the drift of dust containing insecticide active ingredients (a.i.) are harmful to honeybees. Therefore, we developed a device for drills, which uses partial recirculation and filtration of the air by means of an anti‐pollen and an electrostatic filter.RESULTSTests were carried out by simulating sowing of seed treated with imidacloprid, thiamethoxam, clothianidin and fipronil. Dust released by the drill in different configurations were analyzed to assess its mass and a.i. concentration, size distribution and particle number concentration. In general, particles with a diameter lower than 2.5 µm (Particulate Matter ‐ PM2.5) and 10 µm (PM10), represent about 40% and 75% of the total dust mass, respectively. The finest size fraction (
      PubDate: 2016-09-08T07:31:14.403767-05:
      DOI: 10.1002/ps.4428
       
  • Companion planting with white yarrow or with feverfew for squash bug,
           Anasa tristis (Hemiptera: Coreidae) management on summer squash
    • Authors: Brian A. Kahn; Eric J. Rebek, Lynn P. Brandenberger, Keith Reed, Mark E. Payton
      Abstract: BACKGROUNDThe squash bug, Anasa tristis (De Geer) is a major insect pest of cucurbits. Control of squash bugs with insecticidal chemicals is difficult to achieve. We investigated the potential of companion planting with white yarrow (Achillea millefolium L.) or feverfew [Tanacetum parthenium (L.) Sch. Bip.] for squash bug management in field plantings of summer squash (Cucurbita pepo L.).RESULTSCompanion planting with white yarrow had few effects. Companion planting with feverfew tended to reduce squash bug populations, but results often were not statistically significant (P ≥ 0.05). Early‐season ventilated row covers (without herbs) neither reduced squash bug populations nor increased squash yields. Herbs reduced marketable squash yields compared with the control only once out of seven experiments.CONCLUSIONThe tested companion planting strategies inconsistently affected squash bug populations on summer squash. Therefore, these strategies are not recommended to commercial producers.
      PubDate: 2016-09-08T04:00:19.557072-05:
      DOI: 10.1002/ps.4427
       
  • How well will stacked transgenic pest/herbicide resistances delay pests
           from evolving resistance?
    • Authors: Jonathan Gressel; Aaron J. Gassmann, Micheal D. K. Owen
      Abstract: Resistance has evolved to single transgenic traits engineered into crops for arthropod and herbicide resistances, and can be expected to evolve to the more recently introduced pathogen resistances. Combining transgenes against the same target pest is being promoted as the solution to the problem. This solution would have worked if used pre‐emptively, but where resistance has evolved, resistance should easily evolve for the second gene in most cases. We propose and elaborate criteria that could be used to evaluate the value of stacked traits for pest resistance management. Stacked partners must: target the same pest species; be in a tandem construct to preclude segregation; be synchronously expressed in same tissues; have similar tissue persistence; target pest species that are still susceptible to at least two stacked partners. Additionally, transgene products must not be degraded in the same manner, and there should be a lack of cross‐resistance to stacked transgenes or to their products. With stacked herbicide resistance transgenes, both herbicides must be used and have the same persistence. If these criteria are followed, and integrated with other pest management practices, resistance may be considerably delayed.
      PubDate: 2016-09-06T09:00:40.298584-05:
      DOI: 10.1002/ps.4425
       
  • Value of Neonicotinoid Seed Treatments to US Soybean Farmers
    • Authors: Terry Hurley; Paul Mitchell
      Abstract: BACKGROUNDThe benefits of neonicotinoid seed treatment to soybean farmers have received increased scrutiny. Rather than use data from small‐plot experiments, this research uses survey data from 500 US farmers to estimate the benefit of neonicotinoid seed treatments to them. As seed treatment users, farmers are familiar with their benefits in the field and have economic incentives to only use them if they provide value.RESULTSOf the surveyed farmers, 51% used insecticide seed treatments, averaging 87% of their soybean area. Farmers indicated that human and environmental safety is an important consideration affecting their pest management decisions and reported aphids as the most managed and important soybean pest. Asking farmers who used seed treatments to state how much value they provided gives an estimate of US$28.04 ha−1 treated in 2013, net of seed treatment costs. Farmer reported average yields provided an estimated average yield gain of 128.0 kg ha−1 treated in 2013, or about US$42.20 ha−1 treated, net of seed treatment costs.CONCLUSIONThese estimates using different data and methods are consistent and suggest the value of insecticide seed treatments to the US soybean farmers that used them in 2013 was around US$28 to US$42 ha−1 treated, net of seed treatment costs.
      PubDate: 2016-08-30T23:20:23.534231-05:
      DOI: 10.1002/ps.4424
       
  • Identifying obstacles and ranking common biological control research
           priorities for Europe to manage most economically important pests in
           arable, vegetable and perennial crops
    • Authors: Jay Ram Lamichhane; Monika Bischoff‐Schaefer, Sylvia Bluemel, Silke Dachbrodt‐Saaydeh, Laure Dreux, Jean‐Pierre Jansen, Jozsef Kiss, Jürgen Köhl, Per Kudsk, Thibaut Malausa, Antoine Messéan, Philippe C. Nicot, Pierre Ricci, Jérôme Thibierge, François Villeneuve
      Abstract: BACKGROUNDEU agriculture is currently in transition from conventional crop protection to integrated pest management (IPM). Because biocontrol is a key component of IPM, many European countries recently have intensified their national efforts on biocontrol research and innovation (R&I) although such initiatives are often fragmented. The operational outputs of national efforts would benefit from closer collaboration among stakeholders via transnationally coordinated approaches since most economically important pests are similar across Europe.RESULTSThis paper proposes a common European framework on biocontrol R&I. It identifies generic R&I bottlenecks and needs as well as priorities for three crop types (arable, vegetable and perennial crops).CONCLUSIONSThe existing gap between the market offers of biocontrol solutions and the demand of growers, the lengthy and expensive registration process for biocontrol solutions and their varying effectiveness due to variable climatic conditions and site‐specific factors across Europe are key obstacles hindering the development and adoption of biocontrol solutions in Europe. Considering arable, vegetable and perennial crops, a dozen of common target pests are identified for each type of crop and ranked by order of importance at European level. Such a ranked list indicates numerous topics on which future joint transnational efforts would be justified.
      PubDate: 2016-08-28T23:35:36.243768-05:
      DOI: 10.1002/ps.4423
       
  • Evaluation of antifungal activities and structure‐activity relationships
           of Coumarin Derivatives
    • Authors: Ping‐Ping Song; Jun Zhao, Zong‐Liang Liu, Ya‐bing Duan, Yi‐ping Hou, Chun‐Qing Zhao, Min Wu, Min Wei, Nian‐he Wang, Ye Lv, Zhao‐Jun Han
      Abstract: BACKGROUNDOsthol is a natural coumarin and lead compound that has been developed into commercial fungicides in China. Natural coumarins comprise five major subtypes—simple coumarins, linear furanocoumarins, angular furanocoumarins, linear pyranocoumarins, and angular pyranocoumarins. Studies pertaining to the antifungal activities of linear pyranocoumarins are few, and no reports exist for the antifungal activities of angular pyranocoumarins. In order to discover more antifungal natural coumarins, we synthesized a series of simple natural coumarins and isolated several plant‐based furanocoumarins and pyranocoumarins using previously described methods. The compounds were biologically evaluated against some plant fungal pathogens.RESULTSSeveral of the 35 coumarins evaluated here exhibited strong activities against specific fungal species, including Compound 25 (Pd‐D‐V, a linear pyranocoumarin), Compound 26 (libanorin, an angular furanocoumarin), and Compound 34 (disenecioyl khellactone, an angular pyranocoumarin). Compound 25 exhibited a high activity against Sclerotinia sclerotiorum (EC50=13.2 µg·mL−1); Compound 34 displayed a strong antifungal activity against Botrytis cinerea (EC50=11.0 µg·mL−1).CONCLUSIONThis study demonstrates that several natural coumarins (one linear pyranocoumarin and one angular pyranocoumarin in particular) exhibit strong antifungal activities. These results compel further studies, where these coumarins can be examined as potential lead compounds for developing novel antifungal agents.
      PubDate: 2016-08-28T23:35:25.622971-05:
      DOI: 10.1002/ps.4422
       
  • Effect of nonwoven fabric covering on residual activity of pendimethalin
           in lettuce and soil
    • Authors: Miroslav Jursík; Jana Kováčová, Martin Kočárek, Kateřina Hamouzová, Josef Soukup
      Abstract: BACKGROUNDLettuce (Lactuca sativa L.) is a crop very sensitive to herbicide contamination due to its short growing season. Use of long‐residual herbicides and nonwoven fabric coverings could therefore influence pendimethalin concentrations in soil and lettuce.RESULTSPendimethalin half‐life in soil ranged between 18 and 85 days and was mainly affected by season (i.e., weather), especially by soil moisture. Pendimethalin degradation in soil was slowest under dry conditions. Longer pendimethalin half‐life was observed under the nonwoven fabric treatment, but the effect of varying application rate was not significant. Pendimethalin residue concentrations in lettuce heads were significantly influenced by pendimethalin application rate and by nonwoven fabric cover, especially at lettuce's early growth stages. The highest pendimethalin concentration at final harvest was determined in lettuce grown on uncovered plots treated by pendimethalin at application rate 1,200 g ha−1 (7–38 µg kg−1). Depending on growing season duration and weather conditions, pendimethalin concentrations in lettuce grown under nonwoven fabric ranged from 0 to 21 µg kg−1.CONCLUSIONUse of transparent nonwoven fabric cover with lettuce can help reduce application rates of soil herbicides and diminish the risk of herbicide contamination in the harvested vegetables.
      PubDate: 2016-08-25T03:46:10.492193-05:
      DOI: 10.1002/ps.4421
       
  • Antifungal activity of fabricated mesoporous alumina nanoparticles against
           rot root disease of tomato caused by Fusarium oxysporium
    • Authors: Mohamed Shenashen; Aly Derbalah, Amany Hamza, Ahmed Mohamed, Sherif El Safty
      Abstract: BACKGROUNDThe present work involved the synthesis and characterization of mesoporous alumina sphere (MAS) nanoparticles to evaluate their biological activity against tomato root rot caused by Fusarium oxysporium, as compared with the recommended fungicide, tolclofos‐methyl, under laboratory and greenhouse conditions. The effects of MAS on the growth of tomato plants were also evaluated and compared with those of tolclofos‐methyl.RESULTSThe physical characteristics and structural features of MAS, such as the large surface‐area‐to‐volume ratio, active surface sites, and open channel pores, caused the high antifungal efficacy against Fusarium oxysporium. MAS presented an antifungal potential similar to that of tolclofos‐methyl and much greater than the control under both laboratory and greenhouse conditions. The highest growth parameters were recorded in tomato plants treated with MAS, followed by those treated with tolclofos‐methyl.CONCLUSIONSOur study demonstrated the possible use of cylindrically cubic MAS as effective alternative to control Fusarium rot root in tomato.
      PubDate: 2016-08-25T03:46:03.902005-05:
      DOI: 10.1002/ps.4420
       
  • Bioassimilable Sulfur Provides Effective Control of Oidium neolycopersici
           in Tomato Enhancing Plant Immune System
    • Authors: Eugenio Llorens; Carlos Agustí‐Brisach, Ana I González‐Hernández, Pilar Troncho, Begonya Vicedo, Teresa Yuste, Marta Orero, Carlos Ledó, Pilar García‐Agustín, Leonor Lapeña
      Abstract: BACKGROUNDDevelopment of alternatives to the use of chemical pesticides to control pests are focused on the induction of natural plant defenses. The study of new compounds based on liquid bioassimilable sulfur and its effect as an inductor of the immune system of plants would provide an alternative option to farmers to enhance plant resistance against pathogen attacks such as powdery mildew. In order to elucidate the efficacy of this compound in tomato against powdery mildew, we tested several treatments: curative foliar, preventive foliar, preventive in soil drench and combining preventive in soil drench and curative foliar.RESULTSIn all cases, treated plants showed lower infection development, better physiological parameters and a higher level of chlorophyll. We also observed better performance in parameters involved in plant resistance such as antioxidant response, callose deposition and hormonal levels.CONCLUSIONThe results indicate that preventive and curative treatments can be highly effective for the prevention and control of powdery mildew in tomato plants. Foliar treatments are able to stop the pathogen development when they are applied as curative. Soil drench treatments induce immune response mechanisms of plants, increasing significantly callose deposition and promoting plant development.
      PubDate: 2016-08-25T03:46:02.444867-05:
      DOI: 10.1002/ps.4419
       
  • An integrated pest control strategy against the Asian tiger mosquito in
           northern Italy: a case study
    • Authors: Frédéric Baldacchino; Francesca Bussola, Daniele Arnoldi, Matteo Marcantonio, Fabrizio Montarsi, Gioia Capelli, Roberto Rosà, Annapaola Rizzoli
      Abstract: BACKGROUNDIn Europe, Aedes albopictus is an invasive mosquito species known to be a major nuisance as well as a vector of a range of arboviruses. A number of studies have indicated that community participation programs are an effective pest control tool to reduce mosquito populations. However, few studies have evaluated the effectiveness of a community‐based approach in Europe. In this study, we examined two Ae. albopictus control strategies that implemented a community‐based approach in northern Italy: one was a partial intervention that included a public education campaign and the larviciding of public spaces, and the other was a full intervention that additionally included a door‐to‐door campaign. This latter consisted of going door to door to actively educate residents about control measures and deliver larvicide tablets for treating catch basins at home. A site where no intervention measures were carried out was used as a control.RESULTSIn the site where a full intervention was carried out, Ae. albopictus egg density was 1.6 times less than at the site that received partial intervention, and 1.9 times less than at the non‐intervention site. No significant reduction in egg density was achieved in the partial intervention site.CONCLUSIONSIn our study, Ae. albopictus populations were most effectively reduced by larviciding both public and private catch basins. Door‐to‐door education was effective in convincing residents to apply control measures on their property; however, this method was labor intensive and costly. It may be possible to reduce personnel costs by involving volunteers or using a ‘hot spot’ approach.
      PubDate: 2016-08-19T04:55:41.556767-05:
      DOI: 10.1002/ps.4417
       
  • Distributions of imidacloprid, imidacloprid‐olefin and
           imidacloprid‐urea in green plant tissues and roots of rapeseed (Brassica
           napus) from artificially contaminated potting soil
    • Authors: Marcela Seifrtova; Tatana Halesova, Klara Sulcova, Katerina Riddellova, Tomas Erban
      Abstract: BackgroundImidacloprid‐urea is the primary imidacloprid soil metabolite, whereas imidacloprid‐olefin is the main plant‐relevant metabolite and is more toxic to insects than imidacloprid. We artificially contaminated potting soil and used quantitative UHPLC‐QqQ‐MS/MS to determine the imidacloprid, imidacloprid‐olefin and imidacloprid‐urea distributions in rapeseed green plant tissues and roots after 4 weeks of exposure.ResultsIn soil, the imidacloprid/imidacloprid‐urea molar ratios decreased similarly after the 250 and 2500 µg/kg imidacloprid treatments. The imidacloprid/imidacloprid‐urea molar ratios in the root and soil were similar, whereas in the green plant tissue, imidacloprid‐urea increased more than two‐fold compared to the root. Although imidacloprid‐olefin was prevalent in the green plant tissues with imidacloprid/imidacloprid‐olefin molar ratios of 2.24 and 1.47 for the 250 and 2500 µg/kg treatments, respectively, it was not detected in the root. However, imidacloprid‐olefin was detected in the soil after the 2500 µg/kg imidacloprid treatment.ConclusionsSignificant proportions of imidacloprid‐olefin and imidacloprid‐urea in green plant tissues were demonstrated. The greater imidacloprid supply increased the molar ratio of imidacloprid‐olefin/imidacloprid in the green plant tissues. The absence of imidacloprid‐olefin in the root excluded its re‐transport from leaves. The similar imidacloprid/imidacloprid‐urea ratios in the soil and root indicated that the root serves primarily for transporting these substances.
      PubDate: 2016-08-19T04:51:39.911353-05:
      DOI: 10.1002/ps.4418
       
  • Pathogenic nature of Syncephalastrum in Atta sexdens rubropilosa fungus
           gardens
    • Authors: Mariana O. Barcoto; Felipe Pedrosa, Odair C. Bueno, Andre Rodrigues
      Abstract: BACKGROUNDLeaf‐cutter ants are considered a major herbivore and agricultural pest in the Neotropics. They are often controlled by environmentally persistent insecticides. Biological control using pathogenic fungi is regarded as an alternative for the management of these insects. Here, we assess whether the filamentous fungus Syncephalastrum sp. is a pathogenic microorganism, responsible for a characteristic disease in fungus gardens. We also characterize the damage caused by this fungus by evaluating physiological and behavioral responses of Atta sexdens rubropilosa sub‐colonies infected with Syncephalastrum sp.RESULTSSyncephalastrum sp. fulfills Koch's postulates, characterizing it as a pathogenic microorganism. Ant workers recognize the infection and remove contaminated fragments from the fungus garden. Syncephalastrum sp. infection causes an interruption of foraging activity, an increase in ant mortality, sub‐colony deterioration and increase in the amount of waste generated, all resulting in sub‐colony death. Syncephalastrum sp. also inhibits the ant fungal cultivar in vitro. The pathogenic effect of Syncephalastrum sp. does not depend on host morbidity or stress (e.g., worker mortality caused by an entomopathogenic fungus).CONCLUSIONSyncephalastrum sp. treatment resulted in progressive damage in sub‐colonies. The interactions among Syncephalastrum sp., fungus garden and ants offer new opportunities in integrated pest management of leaf‐cutting ants.
      PubDate: 2016-08-19T04:40:39.329224-05:
      DOI: 10.1002/ps.4416
       
  • Termiticidal lectins from Myracrodruon urundeuva (Anacardiaceae) cause
           midgut damages when ingested by Nasutitermes corniger (Isoptera;
           Termitidae) workers
    • Authors: Thâmarah A. Lima; Kenner M. Fernandes, Ana Patrícia S. Oliveira, Leonardo P. Dornelles, Gustavo F. Martins, Thiago H. Napoleão, Patrícia M.G. Paiva
      Abstract: BACKGROUNDMyracrodruon urundeuva is a hardwood tree whose bark, heartwood, and leaf contain lectins (MuBL, MuHL and MuLL, respectively) with termiticidal activity against Nasutitermes corniger. In this work, the effects of these lectins on the midgut of N. corniger workers were evaluated.RESULTSThe insects were supplied with an artificial diet containing the lectins at their respective LC50 (previously determined). Forty‐eight hours after the treatment, the midguts were dissected and fixed for histopathology analyses. Toluidine blue‐stained midguts from lectin‐treated workers showed disorganization, with presence of debris in the lumen and absence of the brush border. Fluorescence microscopy revealed that the numbers of digestive and proliferating cells were lower in lectin‐treated individuals than in the control, and caspase‐3 staining confirmed occurrence of cell apoptosis. Enteroendocrine cells were not seen in the treated individuals. The midguts from treated insects showed greater staining for peroxidase than the control, suggesting that the lectins caused oxidative stress. Staining with wheat germ agglutinin conjugated to FITC revealed that the lectins interfered with the integrity of the peritrophic matrix.CONCLUSIONThis study showed that termiticidal lectins from M. urundeuva cause severe injuries, oxidative stress and cell death in the midgut of N. corniger workers.
      PubDate: 2016-08-16T21:15:24.999825-05:
      DOI: 10.1002/ps.4415
       
  • Pyrethroid resistance is associated with a kdr‐type mutation (L1014F) in
           the potato tuber moth Tecia solanivora
    • Authors: Tito Bacca; Khalid Haddi, Maria Pineda, Raul Narciso C. Guedes, Eugênio E. Oliveira
      Abstract: BACKGROUNDThe Guatemalan potato tuber moth, Tecia solanivora, has been the most important pest species in Hispanico‐American potato fields since its first record on potatoes in 1956 in Guatemala. This insect pest has been spreading to other parts of the world, including the Canary Islands in Europe. The tuber moth control relies heavily on the use of insecticides, including pyrethroids. Here, we assessed the likelihood of control failures and performed concentration‐response bioassays in five Colombian strains of T. solanivora to evaluate their susceptibilities to the pyrethroid permethrin.RESULTSEvidence of control failures was observed in four strains tested, which exhibited moderate resistance levels (i.e., ranging from 5.4‐ to 24.4‐fold). However, no spatial dependence was observed between the permethrin LC50 values and the geographic distances among the tuber moth strains. In order to evaluate whether permethrin resistance was mediated by potential mutations in the para‐type sodium channels of T. solanivora, the IIS4–IIS6 region of the para gene was PCR‐amplified and sequenced from the five strains tested. As demonstrated across a range of different arthropod species that exhibited knockdown resistance (kdr), we observed a single point substitution (L1014F) at high frequencies in the para gene of all four resistant strains.CONCLUSIONSThis is the first identification of a target‐site alteration based resistance in the Guatemalan potato tuber moth T. solanivora, which is widespread and exhibits high frequencies among geographically distant strains indicating that pyrethroids are probably becoming ineffective for the control of this pest species.
      PubDate: 2016-08-08T13:18:13.091755-05:
      DOI: 10.1002/ps.4414
       
  • Impact of Glyphosate Resistant Corn, Glyphosate Applications, and Tillage
           on Soil Nutrient Ratios, Exoenzyme Activities and Nutrient Acquisition
           Ratios
    • Authors: Michael B. Jenkins; Martin A. Locke, Krishna N. Reddy, Daniel S. McChesney, R.Wade Steinriede
      Abstract: BACKGROUNDWe report results of the last two years of a 7‐year field experiment designed to test the null hypothesis: applications of glyphosate on glyphosate resistant (GR) and non‐resistant (nonGR) corn (Zea mays L.) under conventional tillage and no‐till would have no effect on soil exoenzymes and microbial activity.RESULTSBulk soil (BS) and rhizosphere soil (RS) macronutrient ratios were not affected by either GR or nonGR corn, or glyphosate applications. Differences observed between exoenzyme activities were associated with tillage rather than glyphosate applications. In 2013 nutrient acquisition ratios for bulk and rhizosphere soils indicated P limitations, but sufficient assimilable N. In 2014 P limitations were observed for bulk and rhizosphere soils, in contrast to balanced C and N acquisition ratios in rhizosphere soils. Stoichiometric relationships indicated few differences between glyphosate and non‐glyphosate treatments. Negative correlations between C:P and N:P nutrient ratios and nutrient acquisition ratios underscored the inverse relation between soil nutrient status and microbial community exoenzyme activities.CONCLUSIONSInconsistent relationships between microbial community metabolic activity and exoenzyme activity indicated an ephemeral effect of glyphosate on BS exoenzyme activity. Except for ephemeral effects, glyphosate applications appeared not to affect the function of the BS and RS exoenzymes under conventional tillage or no‐till.
      PubDate: 2016-08-05T02:45:23.642837-05:
      DOI: 10.1002/ps.4413
       
  • Amitraz and its metabolite differentially activate α‐ and
           β‐adrenergic‐like octopamine receptors
    • Authors: Tomo Kita; Takeshi Hayashi, Tomohiro Ohtani, Haruka Takao, Hiroshi Takasu, Genyan Liu, Hiroto Ohta, Fumiyo Ozoe, Yoshihisa Ozoe
      Abstract: BACKGROUNDAmitraz is a formamidine acaricide and insecticide used to control ticks, mites and fleas. N2‐(2,4‐Dimethylphenyl)‐N1‐methyformamidine (DPMF), a metabolite of amitraz, is thought to be an active agent that exerts acaricidal and insecticidal effects by acting as an agonist on octopamine receptors. The emergence of cattle ticks resistant to amitraz is a serious problem that requires urgent attention. The objective of this research was to determine which type of octopamine receptor is the primary target of amitraz and thereby understand the molecular mechanisms of action and resistance to amitraz.RESULTSAmitraz and DPMF potently activated Bombyx mori α‐ and β‐adrenergic‐like octopamine receptors (α‐ and β‐AL OARs) that were stably expressed in HEK‐293 cells. Notably, DPMF elevated intracellular cAMP levels with an EC50 of 79.6 pM in β‐AL OARs, the transcripts of which were prevalently and widely localized in B. mori body parts. Furthermore, DPMF elevated the intracellular Ca2+ levels, with an EC50 of 1.17 nM in α‐AL OARs.CONCLUSIONAlthough both amitraz and DPMF acted as OAR agonists, the metabolite DPMF was more potent than amitraz and differentially activated α‐ and β‐AL OARs. The present findings provide a basis for studies to examine the mechanism of amitraz resistance and to develop novel acaricides and insecticides.
      PubDate: 2016-08-03T02:50:30.805151-05:
      DOI: 10.1002/ps.4412
       
  • Can Herbicide Safeners Allow Selective Control of Weedy Rice Infesting
           Rice Crops?
    • Authors: Roberto Busi; Nghia K Nguyen, Bhagirath S Chauhan, Francesco Vidotto, Maurizio Tabacchi, Stephen B Powles
      Abstract: BACKGROUNDRice is a major field crop of paramount importance for global food security. However, the increased adoption of more profitable and resource‐efficient direct‐seeded rice systems (DSR) has contributed to greater weed infestations including weedy rice that has become a severe problem in several Asian regions. In this study we have developed a conceptually novel method to protect rice plants at high doses of clomazone and triallate.RESULTSThe insecticide phorate applied to rice seeds provided substantial level of protection against the herbicides clomazone or triallate. Fifteen kg phorate ha−1 significantly increased the LD50 values >2‐fold greater than rice plants treated only with clomazone. Twenty kg phorate ha−1 in combination with 2,000 g triallate ha−1 safened rice plants (80% survival) with LD50 >3.4‐fold greater than in phorate‐untreated rice. Weed control efficacy was not lowered by the presence of phorate‐treated rice seeds.CONCLUSIONWeedy rice is one of the most damaging global weeds and a major threat of DSR systems. In this study we have developed a proof‐of‐concept method to allow selective weedy rice control in rice crops. We call for herbicide discovery programs and research to identify candidate safener and herbicide combinations to achieve selective herbicide control of weedy rice and alleviate weed infestations in global rice crops.
      PubDate: 2016-08-03T02:35:24.745099-05:
      DOI: 10.1002/ps.4411
       
  • Rapid Killing of Bed Bugs (Cimex lectularius L.) on Surfaces using Heat:
           Application to Luggage
    • Authors: Catherine Loudon
      Abstract: BACKGROUNDThe resistance of bed bugs (Cimex lectularius L.) to chemical insecticides has motivated development of non‐chemical control methods such as heat treatment. However, because bed bugs tend to hide in cracks or crevices, their behavior incidentally generates a thermally‐insulated microenvironment for themselves. Bed bugs located on the outer surface of luggage are less insulated and potentially more vulnerable to brief heat treatment.RESULTSSoft‐sided suitcases with adult male bed bugs on the outside were exposed to an air temperature of 70‐75 °C. It took 6 minutes to kill all of the bed bugs, even those that had concealed themselves under zipper flaps or decorative piping. During heating, only one bed bug (out of 250 total) moved into the luggage (through a closed zipper). Over long periods of time (24 hours) at room temperature, adult male bed bugs on the exterior of luggage only infrequently moved inside; only 3% (5/170) had moved inside during 24 hours.CONCLUSIONSBrief exterior heat treatment of luggage is a promising way to decrease the spread of bed bugs being transported on the outer surface of luggage. This treatment will not kill bed bugs inside the luggage, but could be a component of integrated management for this pest.
      PubDate: 2016-08-01T00:01:07.142822-05:
      DOI: 10.1002/ps.4409
       
  • Oral delivery of dsRNA lipoplexes to German cockroach protects dsRNA from
           degradation and induces RNAi response
    • Authors: Yu‐Hsien Lin; Jia‐Hsin Huang, Yun Liu, Xavier Belles, How‐Jing Lee
      Abstract: BACKGROUNDIn the past years, the concept of RNAi application for insect pest control has been proposed, considering the disruption of vital genes. However, the efficiency of RNAi is variable between different insect groups, especially by oral delivery of dsRNA. The purpose of this study is to assess the possibilities of RNAi as a tool for pest control using oral delivery of the dsRNAs encapsulated by liposome in the German cockroach Blattella germanica, which is highly sensitive to RNAi by injection of dsRNAs.RESULTSInjecting dsRNA into the abdomen of B. germanica caused dramatic depletion of essential α‐tubulin gene and mortality. In contrast, oral delivery of the naked dsRNA resulted in lower RNAi efficiency accounted for rapid degradation of the dsRNA in the midgut of B. germanica. Notably, we have further demonstrated that continuous ingestion of dsRNA lipoplexes, which dsRNA was encapsulated with a cationic liposome carrier, was sufficient to slow down the degradation of dsRNA in the midgut and to increase the mortality of the German cockroach by significantly inhibiting α‐tubulin expression in the midgut.CONCLUSIONWe provide the empirical evidence that the formulation of dsRNA lipoplexes could be a plausible approach for insect pest control based on RNAi.
      PubDate: 2016-07-29T06:20:33.573851-05:
      DOI: 10.1002/ps.4407
       
  • Estimating the effect of plant‐provided food supplements on pest
           
    • Authors: Tarryn Schuldiner‐Harpaz; Moshe Coll
      Abstract: BACKGROUNDPlant‐provided food supplements can influence biological pest control by omnivorous predators in two counteracting ways: (i) enhance predator populations, but (ii) reduce pest consumption by individual predators. Yet the majority of studies address only one of these aspects. Here, we first tested the influence of canola (Brassica napus L.) pollen supplements on the life history of two ladybeetle species: Hoppodamia variegata (Goeze) and Coccinella septempunctata (L.). We then developed a theoretical model to simulate total pest consumption in the presence and absence of pollen supplements.RESULTSSupplementing a prey diet with canola pollen increased H. variegata larvae survival from 50% to 82%, and C. septempunctata female oviposition by 1.6 fold. Model simulations revealed a greater benefit of pollen supplements when relying on C. septempunctata for pest suppression than on H. variegata.CONCLUSIONFor these two predators, the tested pollen serves as an essential supplement to a diet of prey. However, the benefit of a mixed prey‐pollen diet was not always sufficient to overcome individual decrease in pest consumption. Taken together, our study highlights the importance of addressing both positive and negative roles of plant‐provided food supplements in considering the outcome for biological control efforts that rely on omnivorous predators.
      PubDate: 2016-07-29T06:20:23.772466-05:
      DOI: 10.1002/ps.4410
       
  • Determining the geographical origin of Asian longhorn beetle (Anoplophora
           glabripennis) specimens using stable isotope and trace element analyses
    • Authors: Katharina Heinrich; Larissa Collins
      Abstract: BACKGROUNDAn outbreak of EU quarantine listed pest Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambicidae), Asian Longhorn Beetle, in Kent (UK) resulted in environmentally and financially costly eradication action being taken. In this study the potential of using multi‐element stable isotope or trace element analyses to determine the geographical origin of individual specimens has been investigated.RESULTSThe isotope ratios of A. glabripennis individuals for hydrogen varied within and across 5 locations. Carbonisotope ratios fell within the expected values for C3 plants (trees using the photosynthetic pathway common for moderate climates). Nitrogen isotope ratios indicated separation of UK laboratory from American (New York, Ohio, Massachusetts) beetles; whilst sulfur isotope ratios distinguished beetles from New York against the other 4 locations. Three trace elements (TEs) separated UK laboratory‐reared beetles from American beetles (Ohio and New York) with ~ 68% confidence.CONCLUSIONSStable isotope and TE analyses show potential to differentiate between newly arrived A. glabripennis individuals and those from previously undetected in‐country populations, which would be of immediate practical benefit in making appropriate strategic decisions on surveillance and eradication. Analyses of additional samples (i) from the same populations, (ii) different locations and (iii) variety of host trees will enhance the overall picture.
      PubDate: 2016-07-29T06:15:45.448612-05:
      DOI: 10.1002/ps.4408
       
  • Intermediate derivatization method in the discovery of new acaricide
           candidate: synthesis of N‐substituted piperazines derivatives and their
           activity against phytophagous mites
    • Authors: Yong Xie; Ying Xu, Changling Liu, Aiying Guan, Lanfeng Ban, Fei Ding, Wei Peng
      Abstract: BACKGROUNDTo discover and exploit novel acaricidal compounds, a series of novel N‐substituted piperazines derivatives were designed and synthesized using a tert‐butyl piperazine‐1‐carboxylate as starting material by intermediate derivatization methods and their acaricidal activities were evaluated.RESULTSThe acaricidal activity showed compounds 11 and 12 exhibited significant acaricidal activity against adults of Tetranychus cinnabarinus in greenhouse tests. Compound 12 in particular was found to be the best potential candidate acaricide and proved more active than that of the commercial positive controls spirodiclofen and pyridaben, with an LC50 of 0.8977 mg L−1. The results of acaricidal activities against larvae and eggs of Tetranychus cinnabarinus indicated that compound 12 possessed equivalent larvicidal activity to spirodiclofen and higher larvicidal activity than pyridaben. Meanwhile, compound 12 showed less ovicidal activity than pyridaben, but higher activity than spirodiclofen. Furthermore, the results of the field trial demonstrated that compound 12 could effectively control Panonychus citri and Panonychus ulmi with long‐lasting persistence and rapid‐acting property.CONCLUSIONSThe present work indicates that compound 12 could be a novel acaricide candidate for spider mites control.
      PubDate: 2016-07-23T03:15:32.568748-05:
      DOI: 10.1002/ps.4369
       
  • Synthesis and Insecticidal Activity of Novel Pyrimidine Derivatives
           Containing Urea pharmacophore against Aedes aegypti
    • Authors: Xing‐Hai Liu; Qiao Wang, Zhao‐Hui Sun, David E. Wedge, James J. Becnel, Alden S. Estep, Cheng‐Xia Tan, Jian‐Quan Weng
      Abstract: BACKGROUNDAedes aegypti is a major mosquito vector for the transmission of serious diseases, especially dengue and yellow fever. More than one billion people in developing countries are at risk. The widespread and continual use of pesticides can lead to resistant mosquitoes. In order to maintain mosquito control gains, it is critical to develop and evaluate novel bioactive molecules that differ in mode of action from currently used products.RESULTSA series of novel pyrimidine derivatives were designed and synthesized. Their structures were elucidated by 1H NMR and HRMS. Biological activities of these compounds were tested against Aedes aegypti. Many of them exhibited insecticidal activity against adult and larval mosquitoes. Compound 4d displayed relatively good activity to reach 70% mortality at 2 µg/mL. Furthermore, DFT (Density functional theory) calculations were established to study the structure‐activity relationship of these novel compounds.CONCLUSIONA practical synthetic route for pyrimidine derivatives is presented. This study suggests that these pyrimidine derivatives exhibited some activity against the yellow fever mosquito, and with further structure modification, could be novel lead compounds for the development of insecticides against mosquitoes.
      PubDate: 2016-07-23T03:15:26.888181-05:
      DOI: 10.1002/ps.4370
       
  • Efficacy of tebuconazole embedded in biodegradable
           poly‐3‐hydroxybutyrate to inhibit the development of Fusarium
           moniliforme in soil microecosystems
    • Authors: Tatiana G Volova; Svetlana V Prudnikova, Natalia O Zhila, Olga N Vinogradova, Anna A Shumilova1, Elena D Nikolaeva, Evgeniy G Kiselev, Ekaterina I Shishatskaya
      Abstract: BackgroundAn important line of research is the development of a new generation of formulations with targeted and controlled release of the pesticide, using matrices made from biodegradable materials. In this study, slow‐release formulations of the fungicide tebuconazole (TEB) have been prepared by embedding it into the matrix of poly‐3‐hydroxybutyrate (P3HB) in the form of films, microgranules, and pellets.ResultsThe average rates of P3HB degradation rates were determined by the geometry of the formulation, reaching for 63 days 0.095‐0.116; 0.081‐0.083; 0.030‐0.055 mg d−1 for films, microgranules, and pellets, respectively. The fungicidal activity of P3HB/TEB against the plant pathogen Fusarium moniliforme was compared with that of the commercial formulation Raxil Ultra. A pronounced fungicidal effect of the experimental P3HB/TEB formulations was observed in 2–4 weeks after application, and it was retained for 8 weeks, without affecting significantly the development of soil aboriginal microflora.ConclusionsTEB release can be regulated by the process employed to fabricate the formulation and the fungicide loading and that TEB accumulates in the soil gradually, as the polymer is degraded. The experimental forms of TEB embedded in the slowly degraded P3HB can be used as a basis for developing slow‐release fungicide formulations.
      PubDate: 2016-07-22T09:20:27.285264-05:
      DOI: 10.1002/ps.4367
       
  • Forward selection for multiple resistance across the non‐selective
           
    • Authors: Pablo Fernández; Ricardo Alcántara, María D. Osuna, Martin Vila‐Aiub, Rafael De Prado
      Abstract: BACKGROUNDIn the Mediterranean area, Lolium species have evolved resistance to glyphosate after decades of continue use without other alternative chemicals in perennial crops (olive, citrus and vineyard). In recent years, oxyfluorfen alone or mixed with glyphosate and glufosinate have been introduced as chemical options to control dicot and grass weeds.RESULTSDose response studies confirmed that three glyphosate resistant Lolium weed species (L. rigidum, L. perenne, L. multiflorum) collected from perennial crops in the Iberian Peninsula have also evolved resistance to glufosinate and oxyfluorfen herbicides, despite their recent introduction. Based on LD50 resistance parameter, resistance factor was similar among Lolium species and ranged from 14‐21‐fold and 10‐12‐fold for oxyfluorfen and glufosinate, respectively. Similarly, about 14‐fold resistance to both oxyfluorfen and glufosinate was estimated in average for the three Lolium species when growth reduction (GR50) was assessed. This study identified oxyfluorfen resistance in a grass species for the first time.CONCLUSIONA major threat to sustainability of perennial crops in the Iberian Peninsula is evident as multiple resistance to non‐selective glyphosate, glufosinate and oxyfluorfen herbicides has evolved in L. rigidum, L. perenne and L. multiflorum weeds.
      PubDate: 2016-07-22T09:20:24.457363-05:
      DOI: 10.1002/ps.4368
       
  • Susceptibility of Selected Boreal Fruits and Berries to the Invasive Pest
           Drosophila suzukii (Diptera: Drosophilidae)
    • Authors: Catherine M Little; Thomas W Chapman, Debra L Moreau, N Kirk Hillier
      Abstract: BACKGROUNDDrosophila suzukii Matsumara has recently emerged as a major invasive pest species in soft‐skinned fruits in berries throughout N. America and Europe. Its distribution has spread so rapidly that little is known of the extent of fruit susceptibility, particularly in boreal regions. Populations of D. suzukii increase dramatically in late summer in boreal regions, concurrent with fruiting seasons for commercially and culturally significant fruits and berries. We tested fruit preference and susceptibility of lingonberry, blueberry, chokecherry, sea buckthorn, and raspberry fruits to D. suzukii.RESULTSFemale D. suzukii attempted to oviposit on all fruit types tested. Fruits with lower brix and lower pH levels were preferred in choice tests. Undamaged lingonberries were relatively safe from infestation; however, bruised or frost‐damaged fruits were easily penetrated. Sea buckthorn and raspberry fruits were highly preferred.CONCLUSIONSAlthough blueberry growers have experienced severe economic crop losses due to D. suzukii, we have found that blueberries were the least preferred of fruits tested. This suggests that D. suzukii are largely opportunistic and highlights the importance of fruit phenology in fruit susceptibility.
      PubDate: 2016-07-22T09:15:59.719798-05:
      DOI: 10.1002/ps.4366
       
  • Systemic RNAi in the small hive beetle (Aethina tumida Murray, Coleoptera:
           Nitidulidae), a serious pest of the European honey bee (Apis mellifera)
    • Authors: Michelle E. Powell; Hannah M. Bradish, John A. Gatehouse, Elaine C. Fitches
      Abstract: BACKGROUNDAethina tumida is a serious pest of the European honey bee (Apis mellifera) in North America and Australia. Here we investigate whether Laccase 2, phenoloxidase gene essential for cuticle sclerotization and pigmentation in many insects, and vacuolar‐ATPase V‐type subunit A, vital for the generation of proton gradients used to drive a range of transport processes, could be potential targets for RNAi‐mediated control of A. tumida.RESULTSInjection of V‐ATPase subunit A (5 ng) and Laccase 2 (12.5 ng) dsRNAs resulted in 100 % larval mortality, qPCR confirmed significant decreases and enhanced suppression of transcript levels over time. Oral delivery of V‐ATPase subunit A dsRNA in solutions resulted in 50 % mortality, however gene suppression could not be verified. We suggest that the inconsistent RNAi effect was a consequence of dsRNA degradation within the gut due to the presence of extracellular nucleases. Target specificity was confirmed by a lack of effect on survival or gene expression in honey bees injected with A. tumida dsRNAs.CONCLUSIONSThis is the first study to show evidence for systemic RNAi in A. tumida in response to injected dsRNA but further research is required to develop methods to induce RNAi effects via ingestion.
      PubDate: 2016-07-22T09:10:32.046249-05:
      DOI: 10.1002/ps.4365
       
  • Costs and benefits of insecticide and foliar nutrient applications to
           HLB‐infected citrus trees
    • Authors: James A. Tansey; Pilar Vanaclocha, Cesar Monzo, Moneen Jones, Philip A. Stansly
      Abstract: BACKGROUNDThe Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae), vectors ‘Candidatus Liberibacter asiaticus’ that causes huanglongbing (HLB). In Florida, HLB incidence is approaching 100% statewide. Yields have decreased and production costs have increased since 2005. Despite this, some growers are maintaining a level of production and attribute this in part to aggressive psyllid control and foliar nutrition sprays. However, the value of these practices is debated. A replicated field study was initiated in 2008 in a commercial block of ‘Valencia’ sweet orange trees to evaluate individual and combined effects of foliar nutrition and ACP control. Results from 2012–2016 are presented.RESULTSInsecticides consistently reduced ACP populations. However, neither insecticide nor nutrition applications significantly influenced HLB incidence nor PCR copy number in mature trees. In reset trees, infection continued to build and reached 100% in all treatments. Greatest yields (kg fruit/ ha) and production (kg s/ ha) were obtained from trees receiving both insecticides and foliar nutrition.CONCLUSIONSAll treatments resulted in production and financial gains relative to controls. However, material and application costs associated with the nutrition component offset these gains resulting in lesser benefits than insecticides applied alone.
      PubDate: 2016-07-18T05:53:45.896665-05:
      DOI: 10.1002/ps.4362
       
  • Structure‐based bioisosterism design, synthesis, insecticidal activity
           and structure‐activity relationship (SAR) of anthranilic diamides
           analogs containing 1,2,4‐oxadiazole rings
    • Authors: Qi Liu; Rui Zhu, Shang Gao, Shi‐Han Ma, Hai‐Jun Tang, Jian‐Jun Yang, Ya‐Mei Diao, Hong‐Lei Wang, Hong‐Jun Zhu
      Abstract: BACKGROUNDAnthranilic diamides derivatives are among the most important classes of synthetic insecticides. Besides the 1,2,4‐oxadiazole heterocycle, a bioisostere of amide, has been extensively used in pesticide. In order to discover novel molecules with high insecticidal activities, a series of anthranilic diamides analogs containing 1,2,4‐oxadiazole rings were designed and synthesized.RESULTSA series of novel anthranilic diamides derivatives containing 1,2,4‐oxadiazole were obtained, and confirmed by 1H NMR, 13C NMR and HRMS. The structure of 3‐bromo‐N‐(4‐chloro‐2‐methyl‐6‐(3‐((methylsulfonyl)methyl)‐1,2,4‐oxadiazol‐5‐yl)phenyl)‐1‐(3‐chloropyridin‐2‐yl)‐1H‐pyrazole‐5‐carboxamide was further characterized by X‐ray diffraction analysis. In addition, bioassays showed that most of the newly synthesized compounds displayed 100 % mortality against Plutella xylostella at 100 mg L−1. And compound 3IIl showed 90 % larvicidal activities at the concentration of 0.5 mg L−1. The LC50 value of 3IIl was 0.20 mg L−1, which indicated that it may be used as potential leading compound for further structural optimization. Furthermore, a brief comparative molecular field analysis models were established to study the structure‐activity relationship of the title compounds.CONCLUSIONCompound 3IIl may be used as potential leading compound for further structural optimization. And the SAR and CoMFA model could provide reliable clues for further structural optimization.
      PubDate: 2016-07-18T05:53:44.735627-05:
      DOI: 10.1002/ps.4363
       
  • Homozygous and heterozygous point mutations in succinate dehydrogenase
           subunits b, c, and d of Rhizoctonia cerealis conferring resistance to
           thifluzamide
    • Authors: Hai‐Yan Sun; Chao‐Qun Lu, Wei Li, Yuan‐Yu Deng, Huai‐Gu Chen
      Abstract: BACKGROUNDThifluzamide, a succinate dehydrogenase inhibitor (SDHI) fungicide, is a promising fungicide for controlling wheat sharp eyespot (WSE). WSE is caused by Rhizoctonia cerealis. Information on the resistance mechanism of this pathogen to thifluzamide remains unavailable.RESULTSWe used selective re‐culturing and UV mutagenesis to generate thifluzamide resistant mutants. Thifluzamide‐resistant mutants were only generated through UV mutagenesis. Sequence analysis of succinate dehydrogenase (Sdh) genes revealed that two mutants had no mutation in RCSdhB, RCSdhC, and RCSdhD and the other 18 mutants all had at least a one mutation in RCSdhB, RCSdhC, or RCSdhD, either in a homozygous or heterozygous state. The majority of mutants included either RCSdhD‐H116Y or RCSdhC‐H139Y. They showed slight resistance to boscalid, bixafen, and penflufen. Only one mutant possessed RCSdhB‐H246Y and it showed medium resistance to boscalid, penflufen, and a slight resistance to bixafen. All the thifluzamide mutants were sensitive to flutolanil. Compared with their parental isolates, these mutants present no or minor fitness penalties.CONCLUSIONHomozygous and heterozygous point mutations in the succinate dehydrogenase subunits b, c, and d of R. cerealis may be involved in thifluzamide resistance.
      PubDate: 2016-07-14T09:06:00.392682-05:
      DOI: 10.1002/ps.4361
       
  • Synthesis and Biological Activity of a New Class of Insecticides: the
           N‐(5‐Aryl‐1,3,4‐thiadiazol‐2‐yl)amides
    • Authors: Joseph D. Eckelbarger; Marshall H. Parker, Maurice C. H. Yap, Ann M. Buysse, Jonathan M. Babcock, Ricky Hunter, Yelena Adelfinskaya, Jack G. Samaritoni, Negar Garizi, Tony K. Trullinger
      Abstract: BACKGROUNDOptimization studies on a high throughput screening (HTS) hit led to the discovery of a series of N‐(6‐arylpyridazin‐3‐yl)amides with insecticidal activity. It was hypothesized that the isosteric replacement of the pyridazine ring with a 1,3,4‐thiadiazole ring could lead to more potent biological activity and/or broader sap‐feeding pest spectrum. The resulting N‐(5‐aryl‐1,3,4‐thiadiazol‐2‐yl)amides were explored as a new class of insecticides.RESULTSSeveral methods for 2‐amino‐1,3,4‐thiadiazole synthesis were used for the preparation of key synthetic intermediates. Subsequent coupling to variously substituted carboxylic acid building blocks furnished the final targets, which were tested for insecticidal activity against susceptible strains of Aphis gossypii (Glover) (cotton aphid), Myzus persicae (Sulzer) (green peach aphid), and Bemisia tabaci (Gennadius) (sweetpotato whitefly).CONCLUSIONSStructure‐activity relationship (SAR) studies on both the amide tail and the aryl A‐ring of novel N‐(5‐aryl‐1,3,4‐thiadiazol‐2‐yl)amides led to a new class of insecticidal molecules active against sap‐feeding insect pests.
      PubDate: 2016-07-14T08:55:38.584957-05:
      DOI: 10.1002/ps.4359
       
  • Pro‐Insecticidal Approach Towards Increasing In Planta Activity
    • Authors: Lawrence C. Creemer; Natalie C. Giampietro, William Lambert, Maurice C. Yap, Gerrit J. deBoer, Yelena Adelfinskaya, Scott Castetter, Frank J. Wessels
      Abstract: BACKGROUNDThe adrenergic mode of action was investigated for the development of potential new insecticides. Clonidine related analogs were tested against Myzus persicae (Sulzer) and Bemisia tabaci (Gennadius). Clonidine analogs lack translation due to a possible vacuole trapping mechanism. Physical properties modulation via a pro‐drug approach was attempted to overcome this mechanism.RESULTSClonidine showed insecticidal activity against M. persicae and B. tabaci. A pro‐drug of a known open‐chain analog of clonidine, was developed. While the pro‐drug had decreased pKa and increased lipophillicity and displayed good activity against M. persicae and B. tabaci, the activity did not translate on cotton. Metabolic studies showed the pro‐drug was quickly metabolized to the parent compound, and was further metabolized to a known vacuole‐trapped oxazoline analog.CONCLUSIONSAdrenergic active compounds, such as clonidine analogs, show potential as insecticides; however, a designed pro‐drug approach did not overcome lack of translation in this case. Studies confirmed that the synthesized pro‐drug analog metabolized in planta to a proposed vacuole‐trapped compound. One possible explanation for the failure of this approach is that the rate of metabolism and vacuole trapping is faster than translaminar flow and therefore the released pesticide is not biologically available to the target organism.
      PubDate: 2016-07-14T08:55:27.754405-05:
      DOI: 10.1002/ps.4358
       
  • Effects of trans‐2‐Hexenal on Reproduction, Growth and Behavior and
           Efficacy against Pinewood Nematode, Bursaphelenchus xylophilus
    • Authors: Le Cheng; Shuangyu Xu, Chunmei Xu, Hongbao Lu, Zhengqun Zhang, Daxia Zhang, Wei Mu, Feng Liu
      Abstract: BACKGROUNDBursaphelenchus xylophilus is a serious quarantined pest that causes severe damage and major economic losses to pine forests. Because of the adverse effects of some traditional nematicides on human and the environment, new plant toxicants against these nematodes have intensified. Nematicidal activity of trans‐2‐hexenal, which is a six carbon aldehyde present in many plants, was tested against the nematode.RESULTStrans‐2‐Hexenal showed significant efficacy against B. xylophilus at a dose range of 349.5‐699 g m‐3 by fumigation of pine wood logs. Additionally, it had significant nematicidal activity against different life stages of B. xylophilus in‐vitro test, with second‐stage larvae (L2s) being the most sensitive, which had LC50 value of 9.87 µg mL‐1 at 48 h. Egg hatch was also significantly inhibited. Further studies revealed that trans‐2‐hexenal inhibited the reproductive activity of B. xylophilus, with negative effects on reproduction rate and egg numbers. Moreover, trans‐2‐hexenal reduced the body length of B. xylophilus. Respiratory rate and thrashing behavior of B. xylophilus also decreased following treatment with this compound.CONCLUSIONtrans‐2‐hexenal had significant nematicidal activity against B. xylophilus, providing a basis for elucidation of the mode of action of trans‐2‐hexenal against plant parasitic nematodes in future studies.
      PubDate: 2016-07-14T08:55:25.229031-05:
      DOI: 10.1002/ps.4360
       
  • Effect of plant resistance and BioAct WG (Purpureocillium lilacinum strain
           251) on Meloidogyne incognita in a tomato–cucumber rotation in a
           greenhouse
    • Authors: Ariadna Giné; Francisco J Sorribas
      Abstract: BACKGROUNDThe effectiveness of combining resistant tomato with BioAct WG (Purpureocillium lilacinum strain 251; Pl251) against Meloidogyne incognita was assessed in a tomato‐cucumber rotation in greenhouse over two years. Additionally, the enzymatic activity of the fungus, the percentage of fungal egg and juvenile parasitism, cardinal temperatures and the effect of water potential on mycelial growth and the soil receptivity to Pl251 were determined in vitro.RESULTSPlant resistance was the only factor that suppressed nematode and crop yield losses. Percentage of egg parasitism in plots treated with BioAct WG was less than 2.6 %. However under in vitro conditions, Pl251 showed protease, lipase, and chitinase activities, and parasitized 94.5 % of eggs, but no juveniles. Cardinal temperatures were 14.2, 24‐26, and 35.4 °C. The maximum Pl251 mycelial growth was at ‐0.25 MPa and 25 °C. Soil temperatures and water potential in the greenhouse were in the range of the fungus. However, soil receptivity was less in greenhouse soil, irrespective of sterilization, than in sterilized sand.CONCLUSIONSPlant resistance was the only factor able to suppress nematode densities, disease severity and yield losses, and to protect the following cucumber crop. Environmental factors involved in soil receptivity could have negatively affected fungus effectiveness.
      PubDate: 2016-07-14T08:55:23.174418-05:
      DOI: 10.1002/ps.4357
       
  • Effects of Residual Novaluron on Reproduction in Alfalfa Leafcutting Bees,
           Megachile rotundata F. (Megachilidae)
    • Authors: Theresa L. Pitts‐Singer; James D. Barbour
      Abstract: BackgroundThe chitin synthesis inhibitor novaluron can suppress pests that affect alfalfa seed production, but can negatively impact reproductive success in the alfalfa pollinator Megachile rotundata. Novaluron is considered a reduced risk insecticide because it disrupts ecdysis and is nonlethal to adults, but some exposed adult insects have fewer eggs and suppressed egg hatch. For this experiment, bees nested in field cages where they were exposed to alfalfa never treated with novaluron, alfalfa that was recently sprayed, or alfalfa that had been sprayed one and two weeks earlier.ResultsCompared to control, greater proportions of dead eggs and larvae and lower proportions of live prepupae occurred when bees were exposed to recent novaluron sprays as well as one‐ or two‐week old spray residues. Two possible routes of residual pesticide exposure were revealed. Mother bees become contaminated through ingestion or direct contact. Or, pollen‐nectar provisions become contaminated with novaluron 1) on or within leaf pieces that surround provisions or 2) transferred from mother bees’ bodies to provisions.ConclusionWe found strong immature mortality effects of novaluron and its residues on M. rotundata. Understanding all possible pesticide exposure routes for pollinating bees enhances decision‐making for maintaining bee populations while protecting crops.
      PubDate: 2016-07-12T09:25:19.625365-05:
      DOI: 10.1002/ps.4356
       
  • Sorption and desorption characteristics of methyl bromide during and after
           fumigation of pine (Pinus radiata D. Don) logs
    • Authors: Matthew Hall; Adriana Najar‐Rodriguez, Anthony Adlam, Alistair Hall, Don Brash
      Abstract: BACKGROUNDThe sorption and desorption characteristics of methyl bromide (MB) were determined during and after fumigation of recently harvested pine (Pinus radiata D. Don) logs. The effects of dose (48 or 120 g m−3), degree of bark cover (0, 50 or 100%) and end‐grain sealing (sealed or unsealed) on sorption and desorption were determined over time.RESULTSSorption of MB was proportional to the dose applied and dependent on the amount of end‐grain sealed. After 16 h, an average of 70.7 ± 2.5% of the initial concentration remained in the treated space when end‐grains were sealed whereas only 47.3 ± 2.5% remained when unsealed. During aeration, MB was released from logs initially ranging from 2.8 to 8.8 g.h m−3, depending on the treatment. The rate of desorption quickly decreased during aeration.CONCLUSIONThe surface area of a log is the most important factor influencing MB sorption and desorption rates, with greater surface area resulting in a greater (de)sorption rates. Sorption data can now be combined with insect toxicity data to estimate a minimum effective dose of MB for further evaluation; while desorption data can be combined with fumigant plume modelling to assess worker safety.
      PubDate: 2016-07-12T09:16:04.038919-05:
      DOI: 10.1002/ps.4355
       
  • Insecticidal Activity of Novel Thioureas and Isothioureas
    • Authors: William T. Lambert; Miriam E. Goldsmith, Thomas C. Sparks
      Abstract: BACKGROUNDWe hypothesized that exploration of chemical space around compounds with reported insecticidal activity could be a viable strategy for discovering novel, insecticidally active areas of chemistry.RESULTSA series of thioureas and isothioureas were prepared as part of a scaffold‐hopping effort around known insecticidal compounds. Many of these compounds showed excellent activity against key sap‐feeding insect pests in insecticidal bioassays. While analogs bearing monocyclic thiophene head groups showed activity against Myzus persicae (green peach aphid), analogs with diarylethane head groups were active against both M. persicae and Bemisia tabaci (sweetpotato whitefly). Despite compelling activity in these laboratory tests, these compounds showed diminished activity when applied to host plants via tracksprayer.CONCLUSIONSThe initial hypothesis that structural modification of molecules reported to have insecticidal activity would yield novel compounds which also exhibit insecticidal activity was validated. Despite excellent activity in laboratory bioassays, these new compounds failed to show compelling activity in more demanding tracksprayer tests.
      PubDate: 2016-07-08T08:35:25.173009-05:
      DOI: 10.1002/ps.4353
       
  • Weed seed inactivation in soil mesocosms via biosolarization with mature
           compost and tomato processing waste amendments
    • Authors: Yigal Achmon; Jesús D. Fernández‐Bayo, Katie Hernandez, Dlinka G. McCurry, Duff R. Harrold, Joey Su, Ruth M. Dahlquist‐Willard, James J. Stapleton, Jean S. VanderGheynst, Christopher W. Simmons
      Abstract: BACKGROUNDBiosolarization is a fumigation alternative that combines passive solar heating with amendment‐driven soil microbial activity to temporarily create antagonistic soil conditions, such as elevated temperature and acidity, that can inactivate weed seeds and other pest propagules. The aim of this study was to use a mesocosm‐based field trial to assess soil heating, pH, volatile fatty acid accumulation, and weed seed inactivation during biosolarization.RESULTSBiosolarization for 8 days using 2% mature green waste compost and 2 or 5% tomato processing residues in the soil resulted in accumulation of volatile fatty acids in the soil, particularly acetic acid, and >95% inactivation of Brassica nigra and Solanum nigrum seeds. Inactivation kinetics data showed that near complete weed seed inactivation in soil was achieved within the first 5 days of biosolarization. This was significantly greater than the inactivation achieved in control soils that were solar heated without amendment or were amended but not solar heated.CONCLUSIONThe composition and concentration of organic matter amendments in soil significantly affected volatile fatty acid accumulation at various soil depths during biosolarization. Combining solar heating with organic matter amendment resulted in accelerated weed seed inactivation compared to either approach alone.
      PubDate: 2016-07-08T08:35:21.04782-05:0
      DOI: 10.1002/ps.4354
       
  • Eradicating grey squirrel Sciurus carolinensis from urban areas: an
           innovative decision making approach based on lessons learnt in Italy
    • Authors: Daniele Paoloni; Valentina La Morgia
      Abstract: BACKGROUNDEradication of Invasive Alien Species supports the recovery of native biodiversity. In Europe, a new Regulation introduces obligations to eradicate the most harmful invasive species. However, eradications of charismatic mammals may encounter strong oppositions. Considering the case study of the Eastern grey squirrel (Sciurus carolinensis Gmelin, 1788) in central Italy, we developed a structured decision making technique, based on a Bayesian Decision Network model and explicitly considering the plurality of environmental values of invasive species management to reduce potential social conflicts.RESULTSThe model identified priority areas for management activities. These areas corresponded to the core of the grey squirrel range, but they also included peripheral zones, where rapid eradication is fundamental to prevent the spread of squirrels. However, when the model was expanded also integrating the attitude of citizens towards the project, the intervention strategy slightly changed. In some areas, the citizens’ support was limited and this resulted in a reduced overall utility of intervention.CONCLUSIONThe suggested approach extends the scientific basis for the management decisions, evaluated in terms of technical efficiency, feasibility and social impact. Here, the Bayesian Decision Network model analysed the potential technical and social consequences of management actions and it responded to the need of transparency in the decision process, but it can be easily extended to consider further issues, common in many mammal eradication programs. Thanks to its flexibility and comprehensiveness, it provides an innovative example of how to plan rapid eradication or control activities, as required by the new EU Regulation.
      PubDate: 2016-07-01T07:40:24.218874-05:
      DOI: 10.1002/ps.4352
       
  • Toxicity of squamocin on Aedes aegypti larvae, its predators and human
           cells
    • Authors: Marilza S. Costa; Antônio E. G. Santana, Leandro L. Oliveira, José E. Serrão
      Abstract: BACKGROUNDThe mosquito Aedes aegypti transmit virus that cause diverse human diseases and the vector control is an important strategy to avoid their propagation. Plants in Annonaceae are recognized as source to molecules with use in medical and agriculture fields. Molecules of secondary metabolites of Annonaceae plants exhibit insecticidal potential against insect pest and vectors, with highlight to acetogenins that show high toxicity with low doses, which encouraged research to producing new insecticide molecules. Herein, we identify an acetogenin from Annona mucosa seeds (chemical analysis) and provide toxicity test against larvae of A. aegypti (target insect), its predators Culex bigoti and Toxorhynchites theobaldi (non‐target insects) and cytotoxicity to human leukocytes.RESULTSWe identify squamocin (C37H66O7) a fatty acid with presence of bis‐tetrahydrofuran ring. In A. aegypti, this compound exhibited behavioral disturb before larval death, high mortality and require low concentrations to LC50 = 0.01 µg/mL and LC90 = 0.11 µg/mL. However, in predators and human leukocytes the squamocin showed non‐effect toxic which indicate selectivity this molecule to non‐target organism.CONCLUSIONWe identify squamocin from A. mucosa seeds and reported lethal action against A. aegypti and show that it is selective for non‐target insects and has low cytotoxicity on human cell.
      PubDate: 2016-07-01T07:35:40.975195-05:
      DOI: 10.1002/ps.4350
       
  • Studies toward Understanding the SAR around the Sulfoximine Moiety of the
           Sap‐Feeding Insecticide Sulfoxaflor
    • Authors: Ann M. Buysse; Benjamin M. Nugent, Nick X. Wang, Zoltan Benko, Nneka Breaux, Richard Rogers, Yuanming Zhu
      Abstract: BACKGROUNDThe discovery of sulfoxaflor (Isoclast™ active) stemmed from a novel scaffold‐based approach toward identifying bioactive molecules. It exhibits broad spectrum control of many sap‐feeding insect pests, including aphids, whiteflies, hoppers and Lygus. Systematic modifications of the substituents flanking each side of the sulfoximine moiety were carried out to determine if these changes would improve potency.RESULTSStructure activity relationship (SAR) studies showed that with respect to the methylene linker, both mono‐ and di‐substitution with alkyl groups of varying sizes as well as cyclic analogs exhibited excellent control of cotton aphids. However against green peach aphids a decrease in activity was observed with substituents larger than ethyl as well as larger cycloalkyl groups. At the terminal tail there appeared to be a narrow steric tolerance as well, with linear groups or small rings more active against green peach aphids than bulkier groups.CONCLUSIONSA novel series of compounds which explored the substituents flanking the sulfoximine moiety of sulfoxaflor were prepared and tested for bioactivity against cotton aphids and green peach aphids. SAR studies indicated that a decrease in green peach aphid potency was observed at the methylene linker as well as the terminal tail with bulkier substituents. A quantitative structure activity relationship (QSAR) analysis of the compounds revealed significant correlation of activity with two molecular descriptors, vol (volume of a molecule) and GCUT_SMR_3 (molar refractivity). This predictive model helps explain the observed activity with the various substituents.
      PubDate: 2016-07-01T07:35:37.990813-05:
      DOI: 10.1002/ps.4351
       
  • Unrelenting spread of the alien monk parakeet Myiopsitta monachus in
           Israel. Is it time to sound the alarm?
    • Authors: Jose Luis Postigo; Assaf Shwartz, Diederik Strubbe, Antonio‐Román Muñoz
      Abstract: BACKGROUNDMonk parakeets, Myiopsitta monachus Boddaert are native to South America, but have established populations in North America, Europe, Africa and Asia. They are claimed to act as agricultural pests in their native range, and their communal stick nests may damage human infrastructure. Although several monk parakeet populations are present in the Mediterranean basin and temperate Europe, little empirical data are available on their population size and growth, distribution, and potential impact. We investigated the temporal and spatial dynamics of monk parakeets in Israel to assess their invasion success and potential impact on agriculture.RESULTSMonk parakeet populations are growing exponentially at a higher rate than that reported elsewhere. The current Israeli population of monk parakeets comprises approximately 1500 individuals. The distribution of the species has increased and shifted from predominantly urban areas to agricultural landscapes.CONCLUSIONSIn Israel monk parakeet populations are growing fast and have dispersed rapidly from cities to agricultural areas. At present, reports of agricultural damage are scarce. A complete assessment of possible management strategies is urgently needed before the population becomes too large and widespread to allow for cost‐effective mitigation campaigns to be implemented.
      PubDate: 2016-07-01T07:35:32.584788-05:
      DOI: 10.1002/ps.4349
       
  • Insecticide ADME for Support of Early Phase Discovery: Combining Classical
           and Modern Techniques
    • Authors: Michael D. David
      Abstract: The two factors which determine an insecticide's potency are its binding to a target site (intrinsic activity) and the ability of its active form to reach the target site (bioavailability). Bioavailability is dictated by the compound's stability and transport kinetics, which are determined by both physical and biochemical characteristics. At BASF Global Insecticide Research, we characterize bioavailability in early research with an ADME (Absorption, Distribution, Metabolism, and Excretion) approach, combining classical and modern techniques. For biochemical assessment of metabolism, we purify native insect enzymes using classical techniques, and recombinantly express individual insect enzymes which are known to be relevant in insecticide metabolism and resistance. For analytical characterization of an experimental insecticide and its metabolites, we conduct classical radiotracer translocation studies when a radiolabel is available. In discovery, where typically no radiolabel has been synthesized, we utilize modern high‐resolution mass spectrometry to probe complex systems for the test compounds and its metabolites. By using these combined approaches, we can rapidly compare the ADME properties of sets of new experimental insecticides and aid in the design of structures with an improved potential to advance in the research pipeline.
      PubDate: 2016-06-27T03:45:34.207794-05:
      DOI: 10.1002/ps.4345
       
  • Impact of volunteer rice infestation on yield and grain quality of rice
    • Authors: Vijay Singh; Nilda R. Burgos, Shilpa Singh, David R. Gealy, Edward E. Gbur, Ana L. Caicedo
      Abstract: BACKGROUNDVolunteer rice (Oryza sativa L.) grains may differ in physico‐chemical traits from cultivated rice, which may reduce the quality of harvested rice grain. To evaluate the effect of volunteer rice on cultivated rice, fields were surveyed in Arkansas, USA in 2012.RESULTSCropping history that included hybrid cultivars in the previous two years (2010 and 2011) had higher volunteer rice infestation (20%) compared to fields planted previously with inbred rice (5.6%). The total grain yield of rice was reduced 0.4% for every 1% increase in volunteer rice density. The grain quality did not change in fields planted with the same cultivar for three years. Volunteer rice density of at least 7.6% negatively impacted the head rice yield. Volunteer rice density of at least 17.7% reduced the rice grain yield. The protein and amylose contents of rice were not affected until volunteer rice infestation exceeded 30%.CONCLUSIONCrop rotation systems that include hybrid rice are expected to have higher volunteer rice infestation than systems without hybrid rice. It is predicted that at 8% infestation, volunteer rice will start to impact head rice yield and will reduce total yield at 18% infestation. It could alter the chemical quality of rice grain at >30% infestation.
      PubDate: 2016-06-22T03:30:30.546135-05:
      DOI: 10.1002/ps.4343
       
  • Delivery Strategies: RNA Interference in Agriculture and Human Health
    • Authors: Richard W. Heidebrecht
      Abstract: Crop protection through expression of introduced insecticidal proteins is a well‐established technique. Modifications of endogenous gene expression have also been used successfully to produce safe and effective agrochemical products. The existing gene expression regulatory apparatus can be employed to alter messenger ribonucleic acid (mRNA) stability in the host species through a ribonucleic acid‐interference (RNAi) mechanism. Such solutions are currently delivered by incorporation of new genes into the host plant. Direct delivery of RNAi is being extensively explored in the clinic to treat selected human diseases and could be advantageous in agriculture. What are the unifying characteristics of successful delivery agents, and how can we project those observations into the future?
      PubDate: 2016-06-17T06:11:09.389004-05:
      DOI: 10.1002/ps.4341
       
  • Lead Generation in Crop Protection Research: A Portfolio Approach to
           Agrochemical Discovery
    • Authors: Michael R. Loso; Negar Garizi, Vidyadhar B. Hegde, James E. Hunter, Thomas C. Sparks
      Abstract: The need for increased food and feed supply to support future global demand with the added challenges of resistance pressure and an evolving regulatory environment necessitate the discovery of new crop protection agents for growers of today and tomorrow. Lead generation is the critical “engine” for maintaining a robust pipeline of new high‐value products. A wide variety of approaches exist for the generation of new leads, many of which having demonstrated success. Each approach features some degree of merit or benefit while also having some inherent drawback or level of risk. While risk for any single approach can be mitigated in a variety of different ways depending on the approach, long‐term viability of a successful lead generation program merits utilization of a portfolio of different approaches and methodologies for the generation of new leads.
      PubDate: 2016-06-14T08:15:39.460503-05:
      DOI: 10.1002/ps.4336
       
  • Wheat (Triticum aestivum L.)‐based intercropping systems for
           biological pest control: a review
    • Authors: Thomas Lopes; Séverin Hatt, Qinxuan Xu, Julian Chen, Yong Liu, Frédéric Francis
      Abstract: BACKGROUNDWheat Triticum aestivum L.) is one of the most cultivated crops in temperate climates. As its pests are mainly controlled with insecticides which are harmful to the environment and human health, alternative practices such as intercropping have been studied for their potential to promote biological control. Based on the published literature, this study aimed to review the effect of wheat‐based intercropping systems on insect pests and their natural enemies.RESULTSFifty original research papers were obtained from a systematic search of the peer‐reviewed literature. Results from a vote‐counting analysis indicated that, in the majority of studies, pest abundance was significantly reduced in intercropping systems compared with pure stands. However, the occurrence of their natural enemies as well as predation and parasitism rates were not significantly increased. The country where the studies took place, the type of intercropping, and the crop that was studied in the association had significant effects on these results.CONCLUSIONThese findings show that intercropping is a viable practice to decrease insecticide use in wheat production systems. Nevertheless, other practices could be combined with intercropping to favour natural enemies and enhance pest control.
      PubDate: 2016-06-08T04:21:18.46591-05:0
      DOI: 10.1002/ps.4332
       
  • Issue Information - Aims and Scope
    • Pages: 2189 - 2189
      PubDate: 2016-10-27T03:23:09.238711-05:
      DOI: 10.1002/ps.4140
       
  • Issue Information - Info Page
    • Pages: 2190 - 2190
      PubDate: 2016-10-27T03:23:03.3321-05:00
      DOI: 10.1002/ps.4141
       
  • Issue Information - ToC
    • Pages: 2191 - 2192
      PubDate: 2016-10-27T03:23:06.36439-05:0
      DOI: 10.1002/ps.4142
       
  • Detection of Zymoseptoria tritici SDHI-insensitive field isolates carrying
           the SdhC-H152R and SdhD-R47W substitutions
    • Authors: Hilda Dooley; Michael W Shaw, Jeanne Mehenni-Ciz, John Spink, Steven Kildea
      Pages: 2203 - 2207
      Abstract: BACKGROUNDSuccinate dehydrogenase inhibitor (SDHI) fungicides are important in the management of Zymoseptoria tritici in wheat. New active ingredients from this group of fungicides have been introduced recently and are widely used. Because the fungicides act at a single enzyme site, resistance development in Z. tritici is classified as medium-to-high risk.RESULTSIsolates from Irish experimental plots in 2015 were tested against the SDHI penthiopyrad during routine monitoring. The median of the population was approximately 2 times less sensitive than the median of the baseline population. Two of the 93 isolates were much less sensitive to penthiopyrad than the least sensitive of the baseline isolates. These isolates were also insensitive to most commercially available SDHIs. Analysis of the succinate dehydrogenase coding genes confirmed the presence of the substitutions SdhC-H152R and SdhD-R47W in the very insensitive isolates.CONCLUSIONThis is the first report showing that the SdhC-H152R mutation detected in laboratory mutagenesis studies also exists in the field. The function and relevance of this mutation, combined with SdhD-R47W, still needs to be determined. © 2016 Society of Chemical Industry
      PubDate: 2016-04-08T03:20:54.890341-05:
      DOI: 10.1002/ps.4269
       
  • Combining electrostatic powder with an insecticide: effect on
           stored-product beetles and on the commodity
    • Authors: Christos G Athanassiou; Thomas N Vassilakos, Anna C Dutton, Nicholas Jessop, David Sherwood, Garry Pease, Andreja Brglez, Clare Storm, Stanislav Trdan
      Pages: 2208 - 2217
      Abstract: BACKROUNDThe opportunity to reduce the amount of pirimiphos-methyl applied to grain by formulating it in an electrostatic powder was investigated. The insecticidal efficacy of pirimiphos-methyl in EC formulation or formulated using electrostatic powder (EP) as an inert carrier was investigated against Sitophilus oryzae (L.), Oryzaephilus surinamensis (L.), Rhyzopertha dominica (F.) and Tribolium confusum Jacquelin du Val. Furthermore, the adhesive properties of EP to rice, corn and wheat, together with the effect on bulk density and bread- and pasta-making properties, were investigated.RESULTSThe results showed that pirimiphos-methyl formulated with EP provided better efficacy against adults when compared with EC formulation for O. surinamensis and T. confusum, but there was no difference for R. dominica. Progeny production was consistently lower in grain treated with the EP formulation than in grain treated with the EC. Tests showed that EP adhered to the kernels for longer on hard wheat than on maize or rice. In most commodities, EP did not alter the bulk density. Finally, the addition of EP did not affect flour- and bread-making properties, nor the pasta-making properties.CONCLUSIONSThe results of the present study suggest that an EP could be used to reduce the amount of pirimiphos-methyl applied to grain for effective pest control, with no detrimental effects on grain quality. © 2016 Society of Chemical Industry
      PubDate: 2016-04-21T02:31:48.646533-05:
      DOI: 10.1002/ps.4255
       
  • Time-dependent sorption of two novel fungicides in soils within a
           regulatory framework
    • Authors: Anna Gulkowska; Ignaz J Buerge, Thomas Poiger, Roy Kasteel
      Pages: 2218 - 2230
      Abstract: BACKGROUNDConvincing experimental evidence suggests increased sorption of pesticides on soil over time, which, so far, has not been considered in the regulatory assessment of leaching to groundwater. Recently, Beulke and van Beinum (2012) proposed a guidance on how to conduct, analyse and use time-dependent sorption studies in pesticide registration. The applicability of the recommended experimental set-up and fitting procedure was examined for two fungicides, penflufen and fluxapyroxad, in four soils during a 170 day incubation experiment.RESULTSThe apparent distribution coefficient increased by a factor of 2.5–4.5 for penflufen and by a factor of 2.5–2.8 for fluxapyroxad. The recommended two-site, one-rate sorption model adequately described measurements of total mass and liquid phase concentration in the calcium chloride suspension and the calculated apparent distribution coefficient, passing all prescribed quality criteria for model fit and parameter reliability.CONCLUSIONThe guidance is technically mature regarding the experimental set-up and parameterisation of the sorption model for the two moderately mobile and relatively persistent fungicides under investigation. These parameters can be used for transport modelling in soil, thereby recognising the existence of the experimentally observed, but in the regulatory leaching assessment of pesticides not yet routinely considered phenomenon of time-dependent sorption. © 2016 Society of Chemical Industry
      PubDate: 2016-03-21T04:00:24.495552-05:
      DOI: 10.1002/ps.4256
       
  • Clonostachys rosea reduces spot blotch in barley by inhibiting
           prepenetration growth and sporulation of Bipolaris sorokiniana without
           inducing resistance
    • Authors: Birgit Jensen; Peter S Lübeck, Hans JL Jørgensen
      Pages: 2231 - 2239
      Abstract: BACKGROUNDSeveral diseases threaten cereal production, and fungicides are therefore widely used. Biological control is an environmentally friendly alternative, and the fungus Clonostachys rosea is a versatile antagonist, effective against several plant diseases. We studied the ability of C. rosea to control barley leaf pathogens and the mechanisms behind the inhibition, emphasising induced resistance.RESULTSUnder controlled conditions, spray application of C. rosea isolate IK726 to barley leaves reduced Bipolaris sorokiniana severity by up to 70% when applied 24 h before or simultaneously with the pathogen, whereas application 24 h after the pathogen had no effect. IK726 also reduced the sporulation capacity of B. sorokiniana. Microscopy of B. sorokiniana infection revealed that IK726 primarily inhibited conidial germination and appressorium formation, while further pathogen development and host defence reactions (papillae and fluorescent epidermal cells) were unaffected. Likewise, expression of defence-related genes encoding PR proteins was unaltered. In addition to B. sorokiniana, IK726 also reduced infection by Drechslera teres and Rhynchosporium commune.CONCLUSIONC. rosea acted as a protectant against three barley leaf pathogens. B. sorokiniana was directly inhibited by IK726, whereas induced resistance appeared not to be involved. Quantitative microscopy is a powerful tool for elucidating mechanisms involved in disease control. © 2016 Society of Chemical Industry
      PubDate: 2016-03-29T04:00:26.704419-05:
      DOI: 10.1002/ps.4260
       
  • Toxin stability improvement and toxicity increase against dipteran and
           lepidopteran larvae of Bacillus thuringiensis crystal protein Cry2Aa
    • Authors: Jihen Elleuch; Samir Jaoua, Carole Ginibre, Fabrice Chandre, Slim Tounsi, Raida Z Zghal
      Pages: 2240 - 2246
      Abstract: BACKGROUNDBacillus thuringiensis δ-endotoxins are the most widely used biopesticides for controlling economically important crop pests and disease vectors. Improving their efficacy is of great benefit. Here, an improvement in Cry2Aa δ-endotoxin toxicity was attempted via a cry gene over expression system using P20 from B. thuringiensis israelensis.RESULTSThe coexpression of Cry2Aa with P20 resulted in a seven fold increase in its production yield in B. thuringiensis. Generated crystals proved to be significantly more toxic (505.207 µg g−1, 1.99 mg L−1 and 1.49 mg L−1) than the P20-lacking control (720.78 µg g−1, 705.69 mg L−1 and 508.51 mg L−1) against Ephestia kuehniella, Aedes aegypti and Culex pipiens larvae respectively. In vitro, processing experiments revealed a P20-mediated protection of Cry2Aa against degradation under larval gut conditions. Thus, P20 could promote the maintenance of a tightly packaged conformation of Cry2Aa toxins in the larval midgut upon correct activation and binding to its membrane receptors.CONCLUSIONBased on their resistance against excessive proteolysis, Cry2Aa δ-endotoxins, produced in the presence of P20, could be considered as a successful control agent for E. kuehniella and an effective alternative for mosquito control, implying its possible exploitation in pest management programmes. © 2016 Society of Chemical Industry
      PubDate: 2016-03-29T03:20:27.126658-05:
      DOI: 10.1002/ps.4261
       
  • Fate of insecticidal Bacillus thuringiensis Cry protein in soil:
           differences between purified toxin and biopesticide formulation
    • Authors: Truong Phuc Hung; Le Van Truong, Ngo Dinh Binh, Roger Frutos, Hervé Quiquampoix, Siobhán Staunton
      Pages: 2247 - 2253
      Abstract: BACKGROUNDBacillus thuringiensis produces insecticidal proteins known as Cry, and its efficiency and absence of side effects make it the most widely used biopesticide. There is little information on the role of soils in the fate of Cry proteins from commercial biopesticide formulations, unlike toxins from genetically modified crops, which have been intensively studied in recent years. The persistence of Cry in soil was followed under field and laboratory conditions.RESULTSSunlight accelerated loss of detectable Cry under laboratory conditions, but little effect of shade was observed under field conditions. The half-life of biopesticide proteins in soil under natural conditions was about 1 week. Strong temperature effects were observed, but they differed for biopesticide and purified protein, indicating different limiting steps.CONCLUSIONFor the biopesticide, the observed decline in detectable protein was due to biological factors, possibly including the germination of B. thuringiensis spores, and was favoured by higher temperature. In contrast, for purified proteins, the decline in detectable protein was slower at low temperature, probably because the conformational changes of the soil-adsorbed protein, which cause fixation and hence reduced extraction efficiency, are temperature dependent. © 2016 Society of Chemical Industry
      PubDate: 2016-03-24T03:35:22.916319-05:
      DOI: 10.1002/ps.4262
       
  • Synthesis and evaluation of hydroxyazolopyrimidines as herbicides;
           the generation of amitrole in planta
    • Authors: John M Clough; Richard P Dale, Barry Elsdon, Timothy R Hawkes, Bridget V Hogg, Anushka Howell, Daniel P Kloer, Karine Lecoq, Matthew MW McLachlan, Phillip J Milnes, Timothy JC O'Riordan, Saranga Ranasinghe, Stephen E Shanahan, Karen D Sumner, Shanaaz Tayab
      Pages: 2254 - 2272
      Abstract: BACKGROUNDExploiting novel herbicidal modes of action is an important method to overcome the challenges faced by increasing resistance and regulatory pressure on existing commercial herbicides. Recent reports of inhibitors of enzymes in the non-mevalonate pathway of isoprenoid biosynthesis led to the design of a novel class of azolopyrimidines which were assessed for their herbicidal activity. Studies were also undertaken to determine the mode of action responsible for the observed herbicidal activity.RESULTSIn total, 30 novel azolopyrimidines were synthesised and their structures were unambiguously determined by 1H NMR, mass spectroscopy and X-ray crystallographic analysis. The herbicidal activity of this new chemical class was assessed against six common weed species, with compounds from this series displaying bleaching symptomology in post-emergence tests. A structure–activity relationship for the novel compounds was determined, which showed that only those belonging to the hydroxytriazolopyrimidine subclass displayed significant herbicidal activity. Observed similarities between the bleaching symptomology displayed by these herbicides and amitrole suggested that hydroxytriazolopyrimidines could be acting as elaborate propesticides of amitrole, and this was subsequently demonstrated in plant metabolism studies using Amaranthus retroflexus. It was shown that selected hydroxytriazolopyrimidines that displayed promising herbicidal activity generated amitrole, with peak concentrations of amitrole generally being observed 1 day after application. Additionally, the herbicidal activity of selected compounds was profiled against tobacco plants engineered to overexpress 4-diphosphocytidyl-2C-methyl-d-erythritol synthase (IspD) or lycopene β-cyclase, and the results suggested that, where significant herbicidal activity was observed, inhibition of IspD was not responsible for the activity. Tobacco plants overexpressing lycopene β-cyclase showed tolerance to amitrole and the two most herbicidally active triazolopyrimidines.CONCLUSIONSInhibition of IspD leading to herbicidal activity has been ruled out as the mode of action for the hydroxytriazolopyrimidine class of herbicides. Additionally, tobacco plants overexpressing lycopene β-cyclase showed tolerance to amitrole, which indicates that this is the main herbicidal mode of action for amitrole. Results from the metabolic fate study of selected hydroxytriazolopyrimidines suggested that the herbicidal activity displayed by these compounds is due to amitrole production, which was confirmed when tobacco plants overexpressing lycopene β-cyclase also showed tolerance towards two triazolopyrimidines from this study. © 2016 Society of Chemical Industry
      PubDate: 2016-04-04T07:16:05.138757-05:
      DOI: 10.1002/ps.4264
       
  • Survey of indigenous entomopathogenic fungi and evaluation of their
           pathogenicity against the carmine spider mite, Tetranychus cinnabarinus
           (Boisd.), and the whitefly, Bemisia tabaci (Genn.) biotype B
    • Authors: Emine Topuz; Fedai Erler, Emine Gumrukcu
      Pages: 2273 - 2279
      Abstract: BACKGROUNDThe carmine spider mite, Tetranychus cinnabarinus, and the silverleaf whitefly, Bemisia tabaci, are serious pests of both field- and greenhouse-grown crops in south-western Turkey. Control of these pests has been heavily dependent upon chemical pesticides. The objectives of this study were to investigate the occurrence of indigenous entomopathogenic fungi (EPF) in field populations of T. cinnabarinus and B. tabaci, and to evaluate their pathogenicity against these pests. For this purpose, a survey of EPF isolated from field-collected samples of both pests was carried out in Antalya in 2010 and 2011 using the dilution plating method.RESULTSFour indigenous Beauveria bassiana isolates (TUR1-B, TUR2-B, FIN1-B, FIN2-B) were recovered. In pathogenicity bioassays with T. cinnabarinus and B. tabaci biotype B, all the isolates tested were pathogenic to some of the biological stages of both pests to varying degrees. FIN1-B and TUR1-B caused mortalities of up to 50 and 45%, respectively, in adults of T. cinnabarinus, and of over 79 and 37%, respectively, in pupae of B. tabaci with 107 conidia mL−1 suspensions under laboratory conditions 10 days after inoculation. FIN2-B and TUR2-B had mortalities of 19.45 and 12.28%, respectively, in adults of T. cinnabarinus, and of 6.78 and 8.18%, respectively, in pupae of B. tabaci. None of the isolates had an effect on eggs of either species and larvae of the mite.CONCLUSIONOverall results suggest that isolates FIN1-B and TUR1-B have potential for management of T. cinnabarinus and B. tabaci. © 2016 Society of Chemical Industry
      PubDate: 2016-04-06T02:12:35.144987-05:
      DOI: 10.1002/ps.4266
       
  • Sublethal effects of chlorantraniliprole on development, reproduction and
           vitellogenin gene (CsVg) expression in the rice stem borer, Chilo
           suppressalis
    • Authors: Li Huang; Mingxing Lu, Guangjie Han, Yuzhou Du, Jianjun Wang
      Pages: 2280 - 2286
      Abstract: BACKGROUNDThe rice stem borer, Chilo suppressalis (Walker), is one of the most damaging rice pests in the world. The sublethal effects of chlorantraniliprole on development,reproduction and mRNA expression levels of vitellogenin gene (CsVg) in C. suppressalis were investigated.RESULTSExposure of third-instar larvae to sublethal concentrations of chlorantraniliprole (LC10 and LC30) significantly extended larval duration, lowered the mean weight of male pupae and shortened male adult longevity. Pupal duration was significantly prolonged and the mean weight of female pupae was significantly lowered in the LC30 treatment group. While there were no significant sublethal effects on either the adult emergence rate or the egg hatch, the pupation rates in the LC10 treatment group (41.30%) and in the LC30 treatment group (23.98%) were significantly lower than the pupation rate of the control (71.86%), and LC10 and LC30 chlorantraniliprole significantly reduced fecundity, by 32.18 and 52.94% respectively. Furthermore, the expression levels of CsVg mRNA after exposure to LC10 and LC30 chlorantraniliprole significantly decreased, by 42.52 and 47.84% respectively, in 12-h-old female adults.CONCLUSIONSublethal concentrations of chlorantraniliprole adversely affect the development and reproduction of C. suppressalis. The downregulation of CsVg by chlorantraniliprole might have negative impacts on the fecundity of C. suppressalis. © 2016 Society of Chemical Industry
      PubDate: 2016-04-06T02:41:24.323816-05:
      DOI: 10.1002/ps.4271
       
  • Movement and survival of Busseola fusca (Lepidoptera: Noctuidae) larvae
           within maize plantings with different ratios of non-Bt and Bt seed
    • Authors: Annemie Erasmus; Jaco Marais, Johnnie Van den Berg
      Pages: 2287 - 2294
      Abstract: BACKGROUNDProducts of plant biotechnology, for example genetically modified Bt maize, provide useful tools for pest management. The benefits provided by insect-resistant plants are, however, threatened by the evolution of resistance by target pest species. The high-dose/refuge insect resistance management strategy (IRM) as well as seed mixtures are globally used as IRM strategies. Busseola fusca (Lepidoptera: Noctuidae), the target stem borer of Bt maize in Africa, evolved resistance to Bt maize expressing Cry1Ab protein in South Africa. Owing to high larval mobility and subsequent sublethal exposure of larvae moving between non-Bt and Bt plants, more rapid resistance evolution has been proposed as a possibility with deployment of seed mixture strategies.RESULTSLaboratory and field studies were conducted to study B. fusca larval mobility. In the laboratory, different scenarios of B. fusca larval movement between single-gene (Cry1Ab) and stacked-trait (Cry1A.105 and Cry2Ab2) Bt maize were studied. Data on larval survival and mass over time indicated that Cry proteins do not kill larvae above certain developmental stages. A 2 year field study with the single gene and the stacked event was conducted using seed mixtures containing 5, 10, 15 and 20% non-Bt seed as well as a control treatment (non-Bt seed only).CONCLUSIONLarval movement continued for 5 weeks and resulted in a significant incidence of Bt and non-Bt damaged plants, indicating that the movement behaviour of B. fusca is of such a nature that seed mixtures as an IRM strategy may not be effective to delay resistance evolution. © 2016 Society of Chemical Industry
      PubDate: 2016-04-13T05:45:35.410232-05:
      DOI: 10.1002/ps.4273
       
  • Frequency of Cry1F resistance alleles in Spodoptera frugiperda
           (Lepidoptera: Noctuidae) in Brazil
    • Authors: Juliano R Farias; David A Andow, Renato J Horikoshi, Daniel Bernardi, Rebeca da S Ribeiro, Antonio RB do Nascimento, Antonio C dos Santos, Celso Omoto
      Pages: 2295 - 2302
      Abstract: BACKGROUNDThe frequency of resistance alleles is a major factor influencing the rate of resistance evolution. Here, we adapted the F2 screen procedure for Spodoptera frugiperda (J. E. Smith) with a discriminating concentration assay, and extended associated statistical methods to estimate the frequency of resistance to Cry1F protein in S. frugiperda in Brazil when resistance was not rare.RESULTSWe show that F2 screen is efficient even when the resistance frequency is 0.250. It was possible to screen 517 isoparental lines from 12 populations sampled in five states of Brazil during the first half of 2012. Western Bahia had the highest allele frequency of Cry1F resistance, 0.192, with a 95% confidence interval (CI) between 0.163 and 0.220. All other states had a similar and lower frequency varying from 0.042 in Paraná to 0.080 in Mato Grosso do Sul.CONCLUSIONThe high frequency in western Bahia may be related to year-round availability of maize, the high population density of S. frugiperda, the lack of refuges and the high adoption rate of Cry1F maize. Cry1F resistance alleles were not rare and occurred at frequencies that have already compromised the useful life of TC1507 maize in western Bahia. © 2016 Society of Chemical Industry
      PubDate: 2016-04-15T07:25:22.384436-05:
      DOI: 10.1002/ps.4274
       
  • Increasing social welfare by taxing pesticide externalities in the Indian
           cotton sector
    • Authors: Livia Rasche; Alexander Dietl, Nikolinka Shakhramanyan, Divya Pandey, Uwe A Schneider
      Pages: 2303 - 2312
      Abstract: BACKGROUNDPesticide use in the Indian cotton industry has decreased with the introduction of Bt cotton, but rates are still high in comparison with other countries. The adoption of alternative strategies, such as integrated pest management, has been slow, even though benefits are potentially high, more so if the full costs of the external effects of the technologies are taken into account. In order to estimate true societal benefits of different strategies, we compare their external costs and economic performance under external cost taxation, using a state-of-the-art partial equilibrium model of the Indian agricultural sector.RESULTSPesticide externalities lower social welfare in the Indian cotton sector by $US 400–2200 million, depending on the technologies employed. A full internalisation reduces producer revenues by $US 100 ha−1 if only Bt cotton is used, and by $US 30 ha−1 if IPM is another option. Consumers do not start to lose surplus until 20–70% are internalised, and losses are smaller if all technologies are available.CONCLUSIONExternal pesticide costs can be internalised partially without substantially affecting consumer surplus while still increasing social welfare, but producers need to have access to and the knowledge to employ all available cotton production technologies to minimise losses. © 2016 Society of Chemical Industry
      PubDate: 2016-04-15T02:14:27.228915-05:
      DOI: 10.1002/ps.4275
       
  • Genetic variation in target-site resistance to pyrethroids and pirimicarb
           in Tunisian populations of the peach potato aphid, Myzus persicae (Sulzer)
           (Hemiptera: Aphididae)
    • Authors: Kamel Charaabi; Sonia Boukhris-Bouhachem, Mohamed Makni, Brian Fenton, Ian Denholm
      Pages: 2313 - 2320
      Abstract: BACKGROUNDWe used molecular assays to diagnose resistance to pyrethroids and pirimicarb in samples of Myzus persicae from field crops or an insect suction trap in Tunisia. Genotypes for resistance loci were related to ones for polymorphic microsatellite loci in order to investigate breeding systems and patterns of genetic diversity, and to inform resistance management tactics.RESULTSThe kdr mutation L1014F conferring pyrethroid resistance was found in all samples. The M918T s-kdr mutation also occurred in most samples, but only in conjunction with kdr. We discovered a previously unreported genotype heterozygous for L1014F but homozygous for M918T. Samples with modified acetylcholinesterase (MACE) conferring resistance to pirimicarb were less common but widespread. 16% of samples contained both the kdr and MACE mutations. Many unique microsatellite genotypes were found, suggesting that M. persicae is holocyclic in Tunisia. There were no consistent associations between resistance and microsatellite markers.CONCLUSIONThis first study of insecticide resistance in M. persicae in North Africa showed genetic variation in insecticide resistance within microsatellite multilocus genotypes (MLGMs) and the same resistance mechanisms to be present in different MLGMs. This contrasts with variation in northern Europe where M. persicae is fully anholocyclic. Implications for selection and control strategies are discussed. © 2016 Society of Chemical Industry
      PubDate: 2016-04-21T02:20:41.116802-05:
      DOI: 10.1002/ps.4276
       
  • Accurate prediction of black rot epidemics in vineyards using a
           weather-driven disease model
    • Authors: Giovanni Onesti; Elisa González-Domínguez, Vittorio Rossi
      Pages: 2321 - 2329
      Abstract: BACKGROUNDGrapevine black rot caused by Guignardia bidwellii is a serious threat in vineyards, especially in areas with cool and humid springs. A mechanistic, weather-driven model was recently developed for the detailed prediction of black rot epidemics. The aim of this work was to evaluate the model by comparison with observed disease development in leaves and clusters in a vineyard in north Italy from 2013 to 2015.RESULTSThe model accurately predicted disease onset. The probability of predicting new infections that did not occur (i.e. unjustified alarms) was ≤0.180, while the probability of missing actual infections was 0.175 for leaves and 0.263 for clusters. In 78% of these false negative predictions, the difference between expected and actual disease onset was ±2 days; therefore, only one infection period was actually missed by the model. The model slightly overestimated disease severity (mainly on leaves) when the observed disease severity was >0.6.CONCLUSIONThe model was highly accurate and robust in predicting the infection periods and dynamics of black rot epidemics. The model can be used for scheduling fungicide sprays in vineyards. © 2016 Society of Chemical Industry
      PubDate: 2016-04-15T02:20:23.508602-05:
      DOI: 10.1002/ps.4277
       
  • Phenotypical and biochemical characterisation of resistance for parasitic
           weed (Orobanche foetida Poir.) in radiation-mutagenised mutants of
           chickpea
    • Authors: Ines Brahmi; Yassine Mabrouk, Guillaume Brun, Philippe Delavault, Omrane Belhadj, Philippe Simier
      Pages: 2330 - 2338
      Abstract: BACKGROUNDSome radiation-mutagenised chickpea mutants potentially resistant to the broomrape, Orobanche foetida Poir., were selected through field trials. The objectives of this work were to confirm resistance under artificial infestation, in pots and mini-rhizotron systems, and to determine the developmental stages of broomrape affected by resistance and the relevant resistance mechanisms induced by radiation mutagenesis.RESULTSAmong 30 mutants tested for resistance to O. foetida, five shared strong resistance in both pot experiments and mini-rhizotron systems. Resistance was not complete, but the few individuals that escaped resistance displayed high disorders of shoot development. Results demonstrated a 2–3-fold decrease in stimulatory activity of root exudates towards broomrape seed germination in resistant mutants in comparison with non-irradiated control plants and susceptible mutants. Resistance was associated with an induction of broomrape necrosis early during infection. When infested, most of the resistant mutants shared enhanced levels of soluble phenolic contents, phenylalanine ammonia lyase activity, guaiacol peroxidase activity and polyphenol oxidase activity, in addition to glutathione and notably ascorbate peroxidase gene expression in roots.CONCLUSIONResults confirmed enhanced resistance in chickpea radiation-mutagenised mutants, and demonstrated that resistance is based on alteration of root exudation, presumed cell-wall reinforcement and change in root oxidative status in response to infection. © 2016 Society of Chemical Industry
      PubDate: 2016-04-15T07:20:25.608337-05:
      DOI: 10.1002/ps.4278
       
  • Evaluation of spray application methods for navel orangeworm control in
           almonds
    • Authors: James C Markle; Franz JA Niederholzer, Frank G Zalom
      Pages: 2339 - 2346
      Abstract: BACKGROUNDGear Up/Throttle Down (GUTD) and Inward Only strategies represent potential alternatives to conventional airblast applications to reduce spray drift. This study evaluates Inward Only and a modified version of GUTD in almonds, the largest US tree crop, at the recommended hull split treatment timing for control of navel orangeworm (NOW), the key almond insect pest.RESULTSConventional treatment produced the most drift (15.6% of total bifenthrin load), while the GUTD and Inward Only treatments produced only 7.6 and 9.7% respectively. For all methods, 92–94% of the drift was found in the first 15.2 m downwind of the orchard. NOW control was lower for the Inward Only treatment compared with the GUTD and conventional treatments. NOW control was consistently lower at 4.88 m height relative to 2.44 m in all treatments, reflecting the reduced deposition higher in the tree canopy recorded in deposition samples.CONCLUSIONWhile Inward Only treatments reduced spray drift relative to the conventional application method, poorer control of NOW, the key insect pest of almonds, in the Inward Only treatment would likely limit its voluntary use by growers. However, GUTD holds promise for use at the hull split treatment timing to address spray drift. © 2016 Society of Chemical Industry
      PubDate: 2016-04-21T02:45:25.634741-05:
      DOI: 10.1002/ps.4279
       
  • Distinguishing between weedy Amaranthus species based on intron 1
           sequences from the 5-enolpyruvylshikimate-3-phosphate synthase gene
    • Authors: Alice A Wright; William T Molin, Vijay K Nandula
      Pages: 2347 - 2354
      Abstract: BACKGROUNDHybridization between Amaranthus species and the potential for herbicide resistance to be transferred by hybridization are of growing concern in the weed science community. Early detection of evolved herbicide resistance and hybrids expressing resistance to single or multiple herbicides is important to develop an effective control strategy.RESULTSA PCR test was developed for quick identification of weedy amaranths and any hybrids. The sequences of intron 1 for the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS; EC 2.5.1.19) gene were determined for Amaranthus palmeri, A. spinosus, A. retroflexus, A. blitoides, A. viridis, A. tuberculatus and A. hybridus. These sequences were aligned and primers were developed in areas where the sequence differed between species. Species-specific primers and cycle conditions were successfully developed. These primers produce a single robust band only for the species for which they were designed.CONCLUSIONThe PCR techniques described here allow identification of a weedy amaranth or suspect hybrid in a few hours. Using a similar target, it may be possible to design simple PCR tests to identify even more difficult to distinguish weed species or weeds prone to interspecific hybridization. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.
      PubDate: 2016-04-19T02:40:27.881739-05:
      DOI: 10.1002/ps.4280
       
 
 
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