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- The effect of Beauveria bassiana on the host location of rice striped stem
borer, Chilo suppressalis by Trichogramma japonicum-
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Abstract: Abstract The rice stem borer, Chilo suppressalis Walker (Lepidoptera: Crambidae), is a key rice pest, causing major yield loss in Asia. Trichogramma japonicum Ashmead (egg parasitoid) and Beauveria bassiana Balsamo Vuillemin (entomopathogenic fungi) are two important organisms used in sequence or integrated for C. suppressalis management. However, few information is available on potential antagonism between the two biocontrol agents. Under laboratory conditions, we assessed whether the presence of B. bassiana had an impact on the oviposition preference of T. japonicum for C. suppressalis eggs. We characterized parasitic behavior of T. japonicum exposed or not to B. bassiana on C. suppressalis eggs (varying in age) by carrying out observation experiments and using a Y-tube olfactometer. We also evaluated the response of T. japonicum to B. bassiana-affected vs. -unaffected C. suppressalis eggs. Olfactometer tests showed that T. japonicum-vectored B. bassiana and/or C. suppressalis eggs immersed in B. bassiana did not have major effects on choices made by the parasitoid. T. japonicum attacked C. suppressalis eggs of 0-d, 2-d and 4-d old and had preference to fresh host eggs (0-d). However, the contaminated T. japonicum were not able to distinguish between eggs of 0-d old and 4-d old in contrast with the uncontaminated parasitoids. A reduction in insect locomotion (no-response number) of T. japonicum contaminated by B. bassiana preferring to 4-d-old host eggs was found, which was compared to the no-response number of uncontaminated T. japonicum preferring to 0-d-old host eggs. The parasitic behavior of host searching time, checking time, drilling and oviposition time and the parasitism rate (in 24 h) did not differ between the fresh eggs immersed with B. bassiana and control (eggs without B. bassiana). On the other hand, searching and checking times were slightly higher when parasitoids were contaminated by B. bassiana (drilling and oviposition times as well as the parasitism rate in 24 h were not impacted). Therefore, T. japonicum may be used together with B. bassiana in integrated program targeting C. suppressalis.
PubDate: 2023-11-24
- Female melon fruit flies, Zeugodacus cucurbitae, are attracted to a
synthetic chemical blend based on male epicuticular components-
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Abstract: Abstract The melon fly, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae), is considered to be the most destructive pest of melons and other related cucurbit crops worldwide. Despite the potential of behaviour-based control strategies, little is known about the mechanisms involved in female mate choice. Herein, we investigated the production and chemoreception of cuticular hydrocarbons in both sexes of Z. cucurbitae, and the behavioural responses they induce. We studied the epicuticular composition of virgin males and females, using two-dimensional gas chromatography coupled with mass spectrometric detection. Data were interpreted using multivariate factorial analysis. The differentiation of chemical profiles was consistently observed over time. In young individuals, the chemical profiles did not differ between sexes, while sex-specific differences were noted in mature flies. The fly olfactory sensitivity to these compounds was explored using gas chromatography combined with chopped triple electroantennography and electropalpography detectors. This extensive exploration of the pest olfactory sensitivity highlighted three compounds produced by the male. When blended, they induced a robust positive response in unmated naive females in a six-choice olfactometer. The responsiveness of other Tephritidae species (a polyphagous species Bactrocera dorsalis (Hendel) and the cucurbit specialist Dacus demmerezi (Bezzi)) to whole body extracts of Z. cucurbitae was also investigated. Our findings showed that Z. cucurbitae uses species-specific olfactory receptors to detect male produced compounds. In addition, the palps were sensitive to a female-specific component, 1,7-dioxaspiro[5.5]undecane, which the males produce in minute quantities. Overall, this study provides a starting point for a pheromone-based tephritid lure that targets unmated females. The potential implications for pest management are discussed.
PubDate: 2023-11-20
- Phosphine resistance among stored product insect pests: A global
meta-analysis-based perspective-
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Abstract: Abstract Phosphine is the most common fumigant used for stored product protection, and its use intensified with the global phasing out of methyl bromide due to its ozone depletion characteristics. These use patterns led to phosphine resistance, which was subjected to a globe-wide survey in the 1970’s, but without a subsequent (global) update. Thus, the present work aimed to undertake a comprehensive review of the phosphine resistance literature published since the initial survey in 1975 until 2021. Next, meta-analyses were used to synthesize and quantify the resistance observed within the main insect pest species of stored products. Forty-six papers were recognized surveying 13 species of stored product insect species, encompassing 980 populations around the world; 72.96% of these populations exhibited phosphine resistance, and 10 out of the 13 species evaluated exhibited resistance in more than 60% of the populations tested. The most widespread problems were observed with the lesser grain borer (Rhyzopertha dominica), the rice weevil (Sitophilus oryzae), and the red flour beetle (Tribolium castaneum). The frequency of resistant individuals ranged from 12 to 48% for the populations. The levels of phosphine resistance were higher for the lesser grain borer (73-fold on average), followed by the red flour beetle (32-fold), and the maize weevil (28-fold). Furthermore, a considerable variability was observed within species and among localities. Therefore, phosphine resistance remains an ongoing problem and worldwide concern, with increasing levels and prevalence among key pest species of stored products, although reports and monitoring are largely circumscribed to four countries–Australia, Brazil, Greece, and the US.
PubDate: 2023-11-18
- Supplemental LED lighting improves plant growth without impeding
biological control of aphids with parasitoids in a tri-trophic greenhouse
system-
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Abstract: Abstract Artificial lighting, including light-emitting diode (LED) illumination, is increasingly being optimized in protected agricultural systems to maximize plant yield and quality. However, it may also cause other top–down and bottom–up effects in these relatively simple ecological communities that also include insect pests and their natural enemies. While some effects of LED lighting on insects have been demonstrated to date, it is not known how they influence biological control of insect pests in practice. To examine potential top–down and bottom–up impacts of LED illumination on greenhouse biological control with parasitoids, we studied the effects of artificially lengthened days on a tri-trophic system in cages and in a greenhouse. We grew plants under a 12-h photoperiod of white-supplemented light with 6 h of additional (1) white light or (2) red and blue light, or (3) with no additional light. We exposed the plants to the pest aphid Myzus persicae (Hemiptera: Aphididae) with or without its parasitoid wasp Aphidius matricariae (Hymenoptera: Braconidae), or to no insects. The 18-h light treatments increased mean plant dry mass by 127% compared with the 12-h control without affecting the aphid’s population density or the parasitoid’s biological control efficacy, under relatively low light conditions. This suggests that insect communities in protected agriculture can be resilient to even drastic changes in their light environment, and that adjusting crop lighting in a manner that affects plant growth does not necessarily compromise biological control’s effectiveness.
PubDate: 2023-11-14
- Polymeric nanoparticles improve lethal and sublethal effects of essential
oils and pyrethroids toward the rice weevil and the cigarette beetle-
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Abstract: Abstract The rice weevil (Sitophilus oryzae L.) and the cigarette beetle (Lasioderma serricorne F.) are primary and secondary insect pests that cause significant damage to stored grains and commodities. The goal of this study was to evaluate the physicochemical properties and insecticidal activity of Origanum vulgare (L.) (OV) and Laurus nobilis (L.) (LN) essential oils (EOs) in polymeric nanoparticles (PNs) prepared using the melt dispersion technique with polyethylene glycol (PEG 6000) as the matricidal material. In PNs, the monocyclic monoterpenes were retained in high proportions after encapsulation. Physicochemical analyses revealed that OV and LN PNs had mean sizes of 295 and 429 nm, respectively, with a loading efficiency of almost 90%, and a polydispersity index ≤ 0.25 (monodisperse samples). Against Sitophilus oryzae, only OV PN significantly enhanced the lethal effect of EO, whereas on L. serricorne, both PNs. It was demonstrated that, on both pests, OV EO and its PNs increased their sensitivity to pyrethroids, whereas LN oil and their PNs promote this effect only on S. oryzae. The PNs of OV and LN altered the nutritional physiology and behavior variables of both stored product pest and prolonged the repellent effect of the EOs on S. oryzae and L. serricorne up to 60 and 48 h. Ecotoxicity bioassays demonstrated that OV and LN EOs and their PNs were harmless to terrestrial non-target organisms and had slight negative effects on aquatic non-target organisms. Finally, PNs did not affect viability of primary osteoblast cells.
PubDate: 2023-11-04
- Integrating water and insect pest management in agriculture
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Abstract: Abstract Water and herbivory are two of the most crucial factors limiting plant growth, and their management is a critical part of crop production. However, due to climate change, the management of water and pests has become increasingly challenging. Although increasing evidence has suggested strong interactions among water, plants, and insects, the level to which water and insect pest management can be integrated is largely unexplored. This review summarizes and synthesizes current knowledge on the ecology of water-plant-insect interactions and agricultural practices that integrate water management rationale in pest management. We further discuss the importance of these agricultural practices under the context of farming types and regional differences at a global scale. A better understanding of the interactions between water and pest management will likely increase synergism and prevent antagonism among different management practices. The review informs future studies on integrating water and pest management and highlights current knowledge gaps that are essential for integrating water and pest management. We aim to facilitate the development of management strategies that enhance plant stress resilience and agricultural sustainability.
PubDate: 2023-11-03
- Arbuscular mycorrhizal fungi and belowground herbivores interact to
determine plant productivity and performance of subsequently feeding
conspecifics by changing plant metabolites-
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Abstract: Abstract Insect herbivores and arbuscular mycorrhizal fungi (AMF) often occur simultaneously on a host plant, altering plant morphological and biochemical traits and thereby not only affecting each other’s performance, but also plant interactions with subsequent above- or belowground herbivores. Here, we investigate the combined effects of AMF and above- and belowground herbivory on plant productivity and performance of subsequent above- and belowground herbivores. We conducted a 3 × 2 full-factorial experiment with three levels of ‘Herbivory (no herbivory, leaf herbivory, and tuber herbivory) and two levels of ‘AMF inoculation’ (no AMF inoculation and AMF inoculation) in the tuber-plant, potato (Solanum tuberosum). We showed that both AMF and tuber herbivory increased tuber biomass and tuber primary metabolites (protein, starch). Tuber herbivory reduced the performance of subsequent conspecifics feeding on leaves potentially via increased leaf levels of phenolics, α-solanine and α-chaconine. By contrast, it increased the performance of subsequent conspecifics feeding on tubers potentially via increased protein, however, only in plants inoculated with AMF. This indicates that the belowground facilitation among conspecific insects was contingent upon the presence of AMF. Leaf herbivory did not affect subsequent above- or belowground insect performance. These feedings improve our understanding of the ecological consequences of antagonists and mutualists interactions mediated by phytochemistry, especially for agroecosystems.
PubDate: 2023-11-02
- Water stress decreases the biocontrol efficacy of a nucleopolyhedrovirus
against the fall armyworm on maize-
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Abstract: Abstract Drought events are expected to limit crop productivity in the context of current climate change. Drought is also likely to affect multitrophic interactions such as those involving plants, phytophagous insects and their natural enemies. We designed a two-phase experiment to test the effect of water availability and fertilizer treatment on the interaction between maize, the fall armyworm and its nucleopolyhedrovirus pathogen. Plants grown in soil with high irrigation and mineral fertilization had the highest shoot and root dry weight. Furthermore, plant nitrogen levels were higher in plants with fertilization and a low irrigation scheme compared to other treatments. Low irrigation of maize plants reduced virus-induced mortality of armyworm larvae. Insects did not feed on plants with high irrigation and without fertilization. We conclude that water stress and plant nutrition can affect virus performance and thereby affect the efficiency of biological control and pest management, especially as water and nutrient limitation will likely increase under climate change.
PubDate: 2023-10-26
- Long-term data in agricultural landscapes indicate that insect decline
promotes pests well adapted to environmental changes-
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Abstract: Abstract Increasing evidence suggests that land-use intensification contributes to destabilization of trophic networks of insect communities in agriculture resulting in a loss of biodiversity. However, a more detailed understanding of the causes and consequences of the widely reported insect decline is still lacking. Here, we used standardised daily long-term data on the activity of flying insects (~ 250 d/year) to describe the interactive effects of climate warming in intensively cultivated regions and changes in predatory taxa on the general long-term trend of insects and the regulation of herbivores. While the intensely managed landscapes examined in this study show a substantial decline in several taxonomic groups (95.1% total biomass loss in 24 year), the data on aphids support a general assumption that biodiversity loss is often closely associated with arising pest problems. Aphids being pests in agroecosystems develop earlier in spring in overall higher annual abundances. The data highlight that regional insect abundances have declined over recent decades in agricultural landscapes, thus indicating fundamental effects on food webs and insect herbivore performance.
PubDate: 2023-10-24
- Elevated CO2 leads to thick-skinned thrips by altering trehalose and
chitin metabolisms-
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Abstract: Abstract Elevated CO2 (eCO2) can affect the environmental adaptability of herbivorous insects by affecting the quality and quantity of host plants’ nutrients under climate change. In this study, the impacts of eCO2 on carbohydrate metabolism, chitin synthesis and cuticle thickness of western flower thrips (Frankliniella occidentalis) fed on kidney bean (Phaseolus vulgaris) leaves were studied to elucidate the physiological responses of F. occidentalis to eCO2 and provide a theoretical basis for the occurrence trend of thrips under future climate change. The results indicated that the trehalose and glycogen contents in F. occidentalis adults significantly increased with corresponding regulation of key genes related to carbohydrate metabolism under eCO2 compared to ambient CO2 (aCO2), which was closely related to the increased foliar contents of starch and soluble sugars in P. vulgaris grown under eCO2. Subsequently, since trehalose is a precursor of chitin, changes in its content would further affect the chitin synthesis. With the up-regulation of genes related to chitin synthesis and the down-regulation of most genes related to chitin hydrolysis, the chitin content in F. occidentalis adults significantly increased resulting in their increased cuticle thickness and layers, which might enhance their resistance under eCO2 and become “thick-skinned thrips” under climate change condition.
PubDate: 2023-10-21
- Physico-chemical stress alters cuticular semiochemical secretions in the
red flour beetle, Tribolium castaneum adults-
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Abstract: Abstract The red flour beetle, Tribolium castaneum, is the most common coleopteran pest that infests different kinds of stored grains and flours. Under natural conditions, T. castaneum adults secrete benzoquinones as cuticular semiochemicals for aggregation and defensive purposes. In this study, we have examined the physico-chemical effects on the secretion of cuticular semiochemicals in T. castaneum. Adult beetles were exposed to different food flours, starvation, cold, heat and chemical treatments. After 24 h of exposures, cuticular surface chemicals were extracted and analyzed using gas chromatography–mass spectrometry (GC–MS) and gas chromatography–flame ionization detector (GC–FID) techniques. Totally, 14 compounds were identified as cuticular surface chemicals from the body surface of beetles. When exposed to different food flours (chickpea, green gram, rice and wheat), there were no remarkable variations in the secretion of cuticular surface chemicals. Whereas under starvation, cold, heat and chemical stress conditions, remarkable variations (significantly at P ≤ 0.05) were observed in 2-methyl-p-benzoquinone, 2-ethyl-p-benzoquinone and 1-pentadecene secretions. Remarkably, maximum 99.30, 98.79 and 77.41% reductions were observed in 2-methyl-p-benzoquinone, 2-ethyl-p-benzoquinone and 1-pentadecene secretions due to the effect of diallyl disulfide chemical stress, respectively, with the significance of P ≤ 0.05. In conclusion, it was predicted that starvation, cold, heat and chemical stress conditions alter 2-methyl-p-benzoquinone, 2-ethyl-p-benzoquinone and 1-pentadecene secretions in T. castaneum adults rather than food flours.
PubDate: 2023-10-06
- Multiple factors driving the acquisition efficiency of apple proliferation
phytoplasma in Cacopsylla melanoneura-
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Abstract: Abstract Phytoplasmas are bacterial pathogens located in the plant’s phloem that are responsible for several plant diseases and are mainly transmitted by phloem-sucking insects. Apple proliferation (AP) is an economically important disease associated with the presence of ‘Candidatus Phytoplasma mali’ which is transmitted by two psyllid species. While Cacopsylla picta is a vector in different regions, the vector efficiency of C. melanoneura varies between different populations. This species is considered the main AP vector in Northwestern Italy but plays a minor role in Northeastern Italy and other European regions. To investigate whether the psyllid and/or the phytoplasma subtype drive the phytoplasma acquisition in C. melanoneura, a phytoplasma acquisition experiment was set up using single mating couples of overwintered individuals from different psyllid populations and phytoplasma subtypes. All analyzed insect populations acquired phytoplasma, but with different efficiencies and concentrations. The main factors driving the acquisition were the phytoplasma subtype and its concentration in the leaves of the infected trees together with the psyllid lineage. The phytoplasma concentration in the psyllids was again influenced by the phytoplasma subtype, the psyllid lineage and the region of origin, whereas the phytoplasma concentration in the leaves and the psyllid haplotype defined with the cytochrome oxidase I gene had only a minor impact on the phytoplasma concentration. This is the first study evaluating the roles of both the psyllid haplotype and the phytoplasma subtype on the acquisition process and highlights the importance of C. melanoneura as an additional AP vector.
PubDate: 2023-10-06
- Extension of patch residence time of a biocontrol agent by selective
breeding contributes to its early establishment and suppression of a pest
population-
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Abstract: Abstract Biocontrol agents must be released into low densities of insect pests. However, the movement patterns of biocontrol agents rapidly switch from intensive search of prey within patches to extensive search between patches when densities of prey/hosts are very low. This switching can result in the extinction of these agents on the crop, due to either dispersal from crop fields or starvation. We predicted that the foraging behavior of remaining longer per patch (i.e., giving-up time) would be effective in preventing or delaying the emigration of released agents from crop fields, thus improving the efficacy of pest control. We verified this hypothesis using Orius strigicollis, which often establishes poorly after release during periods of low prey density. Selected lines of O. strigicollis with low walking activity were established by artificial selection. Their giving-up time was extended compared with wild-type lines. After feeding on thrips, the selected lines showed search behavior that involved slower travel, more turns, and more time spent immobile compared with the wild-type lines. This behavior was very similar to that observed for intensive search behavior. In greenhouse trials, the selected lines remained on eggplants longer than the wild-type lines and exhibited remarkable pest control efficacy. These results indicate that extension of patch residence time by selective breeding contributes to the early establishment of O. strigicollis and the suppression of thrips.
PubDate: 2023-10-03
- Blue and UV light-emitting diodes (LEDs) disturb the greenhouse whitefly
(Trialeurodes vaporariorum) from its host-
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Abstract: Abstract Push–pull strategy is a well-known and widely used technique for integrated pest management, leading to the reduction of insecticides. This strategy involves the use of mostly visual and chemical stimuli to repel pests from a valuable crop (push) and attract them to an appealing target, e.g., a trap, (pull). Based on former results, this study explored the effect of light-emitting diodes (LEDs) as repelling factors of whiteflies (push). Wavelengths of blue and ultraviolet (UV) were investigated in different light intensities and exposure times in no-choice experiments, under controlled conditions. Whiteflies were exposed directly to LEDs on the underside of tomato leaves and number of repelled insects was counted. The results showed that light intensity and insect repellency were positively related. Insect repellency increased up to tenfold with longer light exposure period. Wavelength of blue and combination of blue + UV repelled more than 87% of whiteflies in light conditions. In darkness, results were only slightly different. The results reveal the property of blue light to repel whiteflies from its host and that addition of UV to blue enhances this effect. They further demonstrate that whitefly vision is dependent on wavelength, light intensity and exposure period. The contribution of the results on understanding the visual behavior of whiteflies and their possible implementation on pest control strategies is discussed.
PubDate: 2023-10-02
- Development of Dermacentor reticulatus ticks in human household conditions
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Abstract: Abstract Companion dogs are at risk of tick infestations. This paper describes cases of transfer of Dermacentor reticulatus ticks by dogs to apartments in eastern Poland, tick development in household conditions, and potential consequences for the residents. For the first time, the preoviposition and oviposition of D. reticulatus females removed from dogs or spontaneously detached from these hosts were studied in household conditions. Similar analyses were performed simultaneously in laboratory settings (25 °C and 75% RH). In the household characterized by a temperature range of 18.5–21.3 °C and 46.9–56% humidity, the preoviposition and oviposition periods with the development of D. reticulatus larvae lasted 20.8 ± 3.1 days and 29.9 ± 1.4 days, respectively. Greater numbers of eggs (2415.8 ± 983.1) were laid by females in the household than laboratory conditions. There were no statistically significant differences in the hatching success between both experiments. The study also provides the first description of infestation of a human by a partially engorged D. reticulatus female that had detached from dog’s skin. Ticks transferred by dogs can develop successfully in human homes. After feeding on dogs, females achieve high reproductive performance. This suggests that dogs may play an important role in the biology of this tick species in urbanized areas.
PubDate: 2023-09-25
- Control of container mosquitoes with triflumuron in key urban land uses
and effects on non-target dipterans-
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Abstract: Abstract Mosquitoes are of major public health importance throughout the world. Recently, there has been an increase in mosquito-borne diseases some of which are newly emerging, and some are remerging. Chemical control remains the main approach to reducing mosquito vector populations, therefore mitigating the transmission and spread of mosquito-borne diseases. Urban land uses have been identified as highly productive for container mosquitoes and thus require vector control interventions. In this study, we compared the effectiveness of the larvicide triflumuron in controlling mosquito vectors in households, cemeteries and tire shops and assessed its potential impact on non-target dipterans in urban temperate Argentina. On average, treatment with triflumuron reduced the occurrence of Aedes aegypti by 81% and Culex pipiens by 45%, with no significant differences among land uses. Two-thirds of the containers with these two mosquito species also harbored at least one non-target dipteran species (other Culicidae, Chironomidae, Psychodidae, Ceratopogonidae, Phoridae, Ephydridae, Syrphidae and Sciomyzidae). Triflumuron application also had unintended effects on non-target dipteran communities, resulting in reduced richness and diversity across all land uses, as well as a reduced density of individuals in tire shops. Triflumuron proved highly effective against Ae. aegypti and moderately effective against Cx. pipiens regardless of land-use patterns. However, unwanted effects against some non-target accompanying Diptera fauna were also recorded, suggesting a severe limitation for the use of this larvicide in areas where biodiversity conservation is of paramount importance. Preserving biodiversity and human welfare must be a primary goal in the search for better vector control measures.
PubDate: 2023-09-15
- Invasion alert for Wasmannia auropunctata: a potential distribution in
southern China and associated invasion risk to urban, rural, agricultural,
and forest lands-
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Abstract: Abstract Wasmannia auropunctata, the little fire ant, is an invasive pest threatening native biodiversity, agricultural and forestry production, and public health. In January 2022, wild populations of W. auropunctata were reported for the first time on the Chinese mainland. However, the stage and degree of W. auropunctata invasion in China are unclear. Therefore, assessing the risk of establishment and the potential impacts associated with this pest is crucial for preventing further spread. This study used the Bayesian additive regression trees (BARTs) model and global occurrence records to assess the potential distribution of W. auropunctata in southern China and the associated risk of invading urban, rural, agricultural, and forest lands. The results from our models indicate that: (1) coastal areas, southwest, and central areas are particularly suitable for W. auropunctata establishment; (2) temperature, clay content, mean normalized differential vegetation index (NDVI), and urban area are important factors in the distribution of W. auropunctata; (3) the agricultural lands in the coastal areas and the Yunnan–Guangxi border, the urban and rural lands in the coastal areas, and grasslands in the southwest should prepare for possible W. auropunctata invasion; and (4) forest lands have the highest area at risk of W. auropunctata invasion in southern China. These results provide valuable information for planning and implementing the monitoring and control strategies against W. auropunctata invasion in China.
PubDate: 2023-09-14
- Effects of elevated CO2 and spinetoram on the population fitness and
detoxification enzymes activities in Frankliniella occidentalis and F.
intonsa-
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Abstract: Abstract Herbivore performance can be impacted by elevated CO2 or insecticides. However, there is insufficient data on how invasive and native species are affected by these dual stresses. Frankliniella occidentalis and F. intonsa are economically important pests. We evaluated the direct effects of elevated CO2 on the sensitivity of thrips to spinetoram, and recorded their population fitness, as well as measured acetylcholinesterase (AChE) and cytochrome P450 (CYP450) activities in adults under short-term (3rd generation) and long-term (30th generation) exposures to these two stresses. Thrips' resistance to spinetoram was accelerated by elevated CO2, and was strongly displayed by F. occidentalis than by F. intonsa. In the 3rd generation, exposure to the two stresses significantly prolonged the longevity of adult F. occidentalis and increased its fecundity, sex ratio, and net reproductive rate (R0), whereas they only increased the fecundity of F. intonsa. Notably, the sex ratio of the former (2.15 ± 0.35) was significantly higher than that of the latter (0.65 ± 0.03). On the other hand, CYP450 activity in F. occidentalis was significantly lower than that of control. At the 30th generation, exposure to the two stresses reduced the population fitness of the two species. Additionally, the fecundity, sex ratio, R0, intrinsic rate of increase (r), and finite rate of increase (λ) of F. occidentalis were significantly higher than that of F. intonsa. Besides, AChE activities in both species were significantly lower than that of the control. We concluded that increased CO2 and spinetoram may hasten the displacement of the native species, F. intonsa by the invasive species, F. occidentalis in the future.
PubDate: 2023-09-13
- The larvae of Phyllotreta striolata share the same olfactory cues for
locating Brassicaceae plant with conspecific adults-
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Abstract: Abstract The sophisticated olfactory system of insects plays crucial roles in host plant location. In comparison with comprehensive studies on the molecular mechanisms of olfactory cues detection in lepidopteran moths, little is known about how coleopteran beetles detect host plant cues. Phyllotreta striolata is a devastating coleopteran pest of Brassicaceae crops, and its larvae feed on roots underground, while its adults destroy leaves aboveground. In this study, we focus on the molecular basis of olfactory cues detection in P. striolata and attempt to determine whether P. striolata larvae share the same specific olfactory cues for host plant location with conspecific adults and whether the detection mechanism is conserved. A two-choice behavioral bioassay was conducted to examine the behavioral responses of P. striolata to different types of isothiocyanates (ITCs), which are the characteristic volatiles of Brassicaceae crops. The results showed that both P. striolata adults and larvae were attracted by allyl ITC, although adults showed a broader behavioral response range. The transcriptome sequencing of P. striolata adults and larvae was performed, and 157 chemosensory genes were identified, among which 6 OBPs, 2 CSPs, 1 OR, 1 IR and 1 GR were found to be preferentially expressed in both P. striolata adults and larvae. Functional studies of PstrOBP9, PstrOBP13 and PstrOBP17, three of the six OBPs that were highly expressed in both adults and larvae, revealed that PstrOBP9 strongly bound allyl ITC and eight other ITCs. Taken together, these findings demonstrated that P. striolata larvae and adults could employ the same olfactory proteins to detect specific plant volatiles for host location, which provides a new perspective on the development of environmentally friendly pest management targeting both P. striolata adults and larvae.
PubDate: 2023-09-11
- Flight phenology and landscape predictors of invasive Coleophora
deauratella populations in Oregon and New Zealand red clover-
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Abstract: Abstract Red clover casebearer moth (Coleophora deauratella) (Leinig and Zeller) (Lepidoptera: Coleophoridae) is an invasive insect pest in red clover (Trifolium pratense L.) seed production systems in North America and New Zealand. Recent discoveries of C. deauratella in Oregon and New Zealand prompted research investigating the seasonal phenology and population dynamics of C. deauratella to inform management strategies and develop a risk prediction framework to mitigate outbreak severity. We sampled 76 site-years across three geographic regions, including western (Willamette Valley) and eastern Oregon and New Zealand. An attractant-based trap network was deployed across sampled regions using a female sex pheromone to lure male moths in commercial red clover seed production fields. Remotely sensed temperature and landscape composition data were extracted for phenological and geospatial modeling. Nonlinear logistic regression was used to develop regionally explicit phenology models that predict the unimodal timing of C. deauratella flights. Molecular gut-content analyses revealed the dietary history of early-season captures and informed landscape analysis covariate selection. A spatial Bayesian generalized linear mixed model (GLMM) was developed to test landscape-level effects of landscape composition and configuration predictors on C. deauratella abundance. The spatiotemporal dominance of clover and grassland land area was positively associated with Oregon C. deauratella populations. These results can be used to forecast C. deauratella risk across space and time and advise integrated pest management practices.
PubDate: 2023-09-07
DOI: 10.1007/s10340-023-01684-8
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