Oviposition behavior in insects has received considerable attention, but studies have mainly focused on the antennae, neglecting the role of the ovipositor. In this study, we investigated the functional characteristics of the ovipositor in oviposition site selection by the fall armyworm (FAW) Spodoptera frugiperda, a destructive invasive pest of maize and other cereals. In oviposition choice assays females exhibited significant repellency to isothiocyanate (ITC), volatiles specific to non-preferred cruciferous plants. Females retained repellency to ITC or attraction to maize volatiles even after antennae removal. Scanning electron microscopy indicated the presence of olfactory-associated sensilla on the ovipositor. Comparative transcriptome analysis and in vitro functional studies showed that S. frugiperda odorant binding protein 30 (SfruOBP30), exclusively expressed in the ovipositor, displayed a broad sensitivity toward 18 maize volatiles and 10 ITC compounds. Site-directed mutant assay revealed that Ser71 and Ser85 were the key binding sites for SfruOBP30 interacting with ITCs and key maize volatiles, respectively. Silencing the expression of SfruOBP30 resulted in the loss of bias in oviposition of FAW, significantly inhibiting their ability to avoid ITCs and locate the maize substrate. Overall, we propose that the ovipositor does not just seek out advantageous conditions for immature stages but more importantly, avoids potential risks during the oviposition process. Apparently, the involvement of SfruOBP30 plays a critical role in detecting both beneficial and harmful substances during this intricate process.

Pigeonpea is one of the world's most important grain legume crops. Mostly grown and consumed in India, where it is a staple food, pigeonpea production also occurs elsewhere in Asia, Africa, Latin America and Australia. Despite widespread cultivation and staple food status, pigeonpea yields have barely increased over the last half century. The prevalence and severity of insect pests present major constraints to increasing pigeonpea yields. Two of the most significant pests of pigeonpea are the lepidopteran ‘pod-borers’– Helicoverpa armigera and Maruca vitrata . The pod fly ( Melanagromyza obtusa ) and several species of pod-feeding Hemiptera are also regular pests, and numerous other minor or sporadic pests have been recorded throughout the cultivated distribution of the crop. Current pigeonpea pest management practices rely heavily on the application of synthetic insecticides. Most research has focused on the management of H. armigera , M. vitrata and M. obtusa due to their damaging feeding behaviour, and the propensity of H. armigera to evolve resistance to synthetic insecticides. Not surprisingly, pest management in pigeonpea is largely based around these three major pests, particularly the lepidopteran pod-borers which appear to be more damaging to modern short-duration cultivars than to older cultivars. A large amount of research has attempted to develop pigeonpea cultivars with conventional host-plant resistance to pod-borers and pod fly, but with limited success. Future pigeonpea pest management research should take a more integrated approach, exploring underexamined areas such as: understanding how modern pigeonpea varieties and traditional landraces respond to pest herbivory, identifying what cultural control methods are available to smallholder farmers, and investigating how biological control can be incorporated into management practices. Future research has the potential to develop IPM strategies in pigeonpea and provide farmers with an alternative to an unsustainable dependence on synthetic insecticides.

Plutella xylostella, a globally economically important pest of cruciferous crops, has varying degrees of resistance to almost all insecticides. Insect gut microbiotas have a variety of physiological functions, and recent studies have shown that they have some potential connection with insecticide resistance. Here, we use metagenomics to analyze the differences in gut microbiota among 5 different populations of P. xylostella resistant to chlorantraniliprole. Differential gene expression was enriched in various metabolic pathways including carbohydrate metabolism, amino acid metabolism, energy metabolism, metabolism of cofactors and vitamins, nucleotide metabolism and so on. Proteobacteria was the dominate phyla, and the relative abundance of common dominant genera in the treated group (CL, Bt, and BtCL) was higher than that in susceptible controls. We successfully isolated 15 species of bacteria, in which the Enterobacter hormaechei was associated with enhanced insecticide resistance. The population we isolated can metabolize chlorantraniliprole in vitro, with a metabolic rate of 34.8 % within 4 days. Our work advances understanding of the evolution of insecticide resistance and lays a foundation for the further exploration of symbiotic microbial associations of lepidopteran insects and their ecological consequences.

The mealybug, Hypogeococcus pungens Granara de Willink (Hemiptera: Pseudococcidae), was released in Australia as a biological control agent for Harrisia martinii (Labour.) Britton (Cactaceae) in 1975. Although the mealybug successfully established in all released locations, its impact has been variable among regions, possibly as a result of climatic differences. Life-history traits (settling time, survival, development time, female reproduction, adult longevity) were compared at 6 constant temperatures (15 to 40 °C) in the laboratory. The mealybug settled on H. martinii at all temperatures tested, but at 15 °C and 40 °C, insects failed to develop and died. Temperature affected female size, fecundity, and integrated performance, all of which were highest at 25 °C. A linear model that fitted temperature to development time indicated a lower developmental threshold of 14.5 °C for both male and female mealybugs. CLIMEX models were developed for the mealybug and its host, H. martinii, and used to investigate the suitability of different regions of Australia, where H. martinii occurs for Hy. pungens. The Hy. pungens CLIMEX model suggests that cold stress limits mealybug growth in southern Queensland and that mealybug performance will vary between regions based on local temperatures. Locations with extreme low winter and extreme high summer temperatures are likely to have the most constrained populations. This may account for the observed differences in the effectiveness of Hy. pungens as a biological control agent at locations within the established range of H. martini in Australia.

The cyclamen mite (CM), Phytonemus pallidus Banks (Acari: Tarsonemidae) is a major pest of greenhouse-cultivated strawberries. In this study, we assessed the influence of seven strawberry cultivars (Albion, Gaviota, Camarosa, Paros, Ventana, Sabrina and Selva) on the life history traits of CM under controlled laboratory conditions (25 ± 1 °C, 65 ± 5% RH, 16:8 h L:D photoperiod). Although CM completed its life cycle on all tested cultivars, developmental duration and population growth parameters varied significantly. The longest development time was observed on Paros (9.2 days), while the shortest occurred on Albion (8.2 days). The highest intrinsic rate of increase (r = 0.164 day⁻¹) and finite rate of increase (λ = 1.178 day⁻¹) were recorded on Sabrina, followed closely by Camarosa (r = 0.161 day⁻¹, λ = 1.174 day⁻¹). In contrast, the lowest values were found on Paros (r = 0.129 day⁻¹, λ = 1.137 day⁻¹), Albion (r = 0.131 day⁻¹, λ = 1.140 day⁻¹) and Selva (r = 0.134 day⁻¹, λ = 1.144 day⁻¹). These results suggest that Sabrina and Camarosa are highly susceptible to CM, whereas Albion, Paros and Selva demonstrate antibiosis resistance. Our findings provide valuable insights for integrated pest management (IPM) strategies targeting CM. However, further validation under greenhouse or field conditions is recommended to confirm cultivar resistance and optimize pest control measures.

In southern China, cowpea production is severely threatened by Megalurothrips usitatus due to its fast-evolving resistance to insecticides. The toxicity monitoring of commonly used insecticides against field populations provides key information for the resistance management of pests. In this study, field populations of Megalurothrips usitatus were collected from three locations (QY, YF, MM) in Guangdong, and the sensitivity of these populations against insecticides was determined by using a thrips insecticides bioassay system (TIBS) method. The bioassay results indicated there were sensitivity variances to insecticides between these three field populations. Among these 10 insecticides, spinetoram and spinosad both showed high toxicity against all three field populations. In addition, broflanilide for QY, emamectin benzoate for YF, and emamectin benzoate and cyantraniliprole for MM were suggested as alternate insecticides to alleviate selective pressure from insecticides on field populations. In field experiments, the corrected control efficacy of cyantraniliprole and spinetoram against M. usitatus was over 75% at 7 dpa, which proved to be ideal insecticides for field application. These field-based results provide guidance for chemical control against thrips and can be valuable in proposing appropriate strategies for thrips resistance management.

Understanding the impact of land-use intensity on aphid-parasitoid food web structure and biological control services is crucial for managing landscapes in a way that supports natural pest regulation. However, few studies have directly linked the structure of these food webs to actual pest control outcomes. In this study, we analyzed how the structure of aphid-parasitoid food webs and the ecosystem services they provide varied across a land-use intensity gradient in 24 alfalfa fields during three years in China. Beta diversity result indicates that the regional species pools play a key role in local food web assembly. Species in plain regions (intensive agricultural areas) were subsets of those found in mountainous region (more diverse landscapes), indicating that land-use intensity filtered out species from the broader regional pool rather than creating unique local assemblages. Land-use intensity, particularly mowing and insecticide application, negatively impacted both primary parasitoid and hyperparasitoid richness and abundance. Conversely, noncrop areas positively influenced primary parasitoid richness. Food web structures varied across regions and sampling dates. Hyperparasitism was significantly correlated with food web structural metrics, showing a negative relationship with modularity and a positive relationship with nestedness in primary-hyperparasitoid food webs. It suggests that hyperparasitoids may be more effective in suppressing primary parasitoids and thereby aphid biocontrol in less modular and more interconnected food webs. These findings highlight the importance of food web structure in shaping parasitoid dynamics and emphasize the need for landscape management strategies that promote biodiversity and ecosystem functions.

Monarch butterflies (Danaus plexippus) are a charismatic and culturally important North American butterfly species famous for their unique, dramatic migratory life history. While non-migratory populations of the species are widespread and apparently stable, migratory populations in North America have recently seen declines, prompting concern that the migratory phenomenon in North America may be at risk of disappearing. In contrast, a relatively recently-established monarch population in Australia has rapidly re-acquired a migratory life history following hundreds of generations of residency and successive bottlenecks as the species island-hopped across the Pacific during the late 1800s and early 1900s. The process by which migration re-emerged in Australian monarchs is not currently known. We raised and sequenced individuals from Queensland, Australia under environmental conditions associated with migration initiation and found strong variance in reproductive diapause, a key migratory trait, between families which was associated with variation at the spectrin beta chain protein Karst. This protein is known to be involved in diapause termination in monarchs but has not previously been identified as associated with migratory life history variance. The most strongly associated migratory SNPs are also present at a low frequency in North America, suggesting that the Australian population is leveraging standing variation which persisted across repeated bottlenecks as Monarchs spread across the Pacific. Our results provide an intriguing example of how the temporary loss of migration—in this case likely over hundreds of generations—may not entail the loss of genetic variation associated with this complex life history strategy.

Despite substantial research examining caterpillar–plant interactions, changes in the feeding behaviour of lepidopteran larvae as they develop are poorly understood. In this study, we investigated ontogenetic changes in the behaviour of Helicoverpa armigera larvae feeding on reproductive structures of pigeonpea (Cajanus cajan). Specifically, we examined the preference for and avoidance of pigeonpea flowers and pods of first, second, third, and fourth instar H. armigera larvae. We also conducted a no-choice assay to compare the ability of third and fourth instar larvae to penetrate pigeonpea pod walls, which act as a physical defence against herbivory. When presented with a choice between pigeonpea pods and flowers, different instars behaved differently. First and second instar larvae largely avoided pigeonpea pods, instead feeding on flowers; third instar larvae initially avoided pods, but by 24 h, did not strongly discriminate between the structures; and fourth instars demonstrated a preference for pods. When initially placed on pods, first instars were slower than other instars to leave these structures, despite pods being suboptimal feeding sites for small caterpillars. We identified a clear instar-specific ability to penetrate through the pod wall to reach the seeds. Most third instar larvae were unable to penetrate the pod wall, whereas most fourth instars succeeded. Third instars suffered a physiological cost (measured by relative growth rate) when boring through the pod wall, which was not observed in fourth instars. Our study further illuminates the insect–plant interactions of the H. armigera–pigeonpea system and provides evidence for the significant changes in feeding behaviour that may occur during lepidopteran larval development.

Tuta absoluta (Lepidoptera: Gelechiidae) originates from the South American tropics but has become a major invasive pest of tomato and other Solanaceae crops worldwide.Agricultural protected facilities (APFs) such as greenhouses and plastic tunnels may provide thermal conditions that allow the survival of T. absoluta in temperate zones with cold winters.In this study, a CLIMEX model was used to investigate the dual effects of increasing use of APFs and climate warming on the potential distribution and seasonal dynamics of T. absoluta in China.Our model showed that the northern boundary for year-round population persistence in China, ignoring APFs, was approximately 30°N, covering about 21% of China's area suitable under current climate.The modelled suitable area increased to 31% and northern boundary for year-round population persistence shifted to 40°N in 2080 under global warming.When APF refuges are included, the potential suitable area was 78% under the current climate and 79% under global warming.This suggests that, in the future, the increasing use of APFs will increase the areas at risk of T. absoluta invasion significantly more than global warming because APFs effectively protect T. absoluta from harsh northern winters.In addition, vegetable production in surrounding open fields will be at risk of invasion during milder seasons when APFs are opened and T. absoluta can disperse.Therefore, the micro-climate of APFs should be considered as part of the invasion process, and Integrated Pest Management should be simultaneously implemented inside and outside APFs for the rational management T. absoluta.

Lepidoptera can cause several health issues in humans and domestic animals due to their setae, which are defensive adaptations that protect them from predators. The diversity of venomous Lepidoptera has been explored in several reviews starting from the first comprehensive attempt in 1984 by Kawamoto and Kumada (KK) who compiled a list of 228 species based on previous reviews; however, KK did not cite the original publications for listed species. In this review we validated and updated the KK table. The updated list of venomous Lepidoptera includes 5 superfamilies, 14 families, 208 genera, and 576 species, representing a two-fold increase for genera and 2.9-fold for species with respect to KK. The total number of species in the genera including at least one venomous species, which we argue is likely closer to the true number of venomous species, is 7 times higher (3,620). GBIF (Global Biodiversity Information Facility) occurrences for venomous species are 1-4 orders of magnitude higher than those of confamilial non-venomous species. The presence of venomous structures is independent of the relatedness of the clades or geographic region; venom is produced by many species of Zygaenoidea, Lasiocampoidea and Bombycoidea but only by some specialized groups in Papilionoidea and Noctuoidea. There are likely to be multiple evolutionary origins of venom within Lepidoptera, but the exact number is difficult to estimate. The knowledge gap between medical and natural history fields needs to be addressed with novel approaches to study ecology and toxicology. This review offers health practitioners a tool to better understand the origin of the reactions observed and to improve the identification of the causal agents.

Helicoverpa armigera Hübner (Lepidoptera: Noctuidae; Hübner) is the major insect pest of pigeon pea [Cajanus cajan; Fabales: Fabaceae; (L.) Millspaugh] worldwide. Research to develop pest management strategies for H. armigera in pigeon pea has focused heavily on developing less susceptible cultivars, with limited practical success. We examined how pigeon pea crop stage influences plant susceptibility to H. armigera using a combination of glasshouse and laboratory experiments. Plant phenology significantly affected oviposition with moths laying more eggs on flowering and podding plants but only a few on vegetative plants. Larval survival was greatest on flowering and vegetative plants, wherein larvae mostly chose to feed inside flowers on flowering plants and on the adaxial surface of expanding leaves on vegetative plants. Larval survival was poor on podding plants despite moths laying many eggs on plants of this stage. When left to feed without restriction on plants for 7 days, larvae feeding on flowering plants were >10 times the weight of larvae feeding on plants of other phenological stages. On whole plants, unrestricted larvae preferred to feed on pigeon pea flowers and on expanding leaves, but in no-choice Petri dish assays H. armigera larvae could feed and survive on all pigeon pea reproductive structures. Our results show that crop stage and the availability of flowers strongly influence pigeon pea susceptibility to H. armigera. An increased understanding of H. armigera-pigeon pea ecology will be useful in guiding the development of resistant varieties and other management tactics.

During preliminary mosquito surveys at Cowley Beach Training Area in north Queensland, Australia, it was found that the utility of the standard encephalitis virus surveillance (EVS) trap for collecting the malaria vector Anopheles farauti (Laveran) adults was compromised by the harsh tropical conditions. With the aim of increasing the survival rate of mosquitoes, we designed a downdraft fan box trap (FBT) that incorporated a screened fan at the bottom of the trap, so mosquitoes did not have to pass through a fan. The FBT was tested against the EVS and Centers for Disease Control (CDC) light traps, where mosquitoes do pass through a fan, and a nonpowered passive box trap (PBT). We conducted 4 trials to compare the quantity and survival of An. farauti and culicine mosquitoes were collected in these traps. Although not significant, the FBT collected more An. farauti than the EVS trap and PBT and significantly less An. farauti than the CDC light trap. However, the FBT improved on the CDC light trap in terms of the survival of An. farauti adults collected, with a significantly higher percentage alive in the FBT (74.6%) than in the CDC light trap (27.5%). Thus, although the FBT did not collect as many anophelines as the CDC, it proved to be superior to current trap systems for collecting large numbers of live and relatively undamaged mosquitoes. Therefore, it is recommended that FBTs be used for collecting An. farauti adults in northern Australia, especially when high survival and sample quality are important.

The Bag-shelter moth, Ochrogaster lunifer (Lepidoptera: Notodontidae), is an Australian endemic species of Thaumetopoeinae with a univoltine life cycle and gregarious, herbivorous larvae. It is variable throughout its range across the continent, most noticeably by the species of host tree used and nest-building behaviour. It has long been considered a species complex by some taxonomists, and the lack of gene flow between populations of ground-nesters and above-ground nesters at the same sites provides strong evidence for at least two species. We tested the specificity of host use and nesting behaviour of ground-nesting and trunk-nesting forms of O. lunifer by transplanting field-collected egg masses to the other form's host, either in their natural position or in the position used by the other form. At the study site, ground-nesting and trunk-nesting (tree-hugger) O. lunifer coexist. Ground-nesting larvae are found on Acacia spp., and egg masses are laid at the base of host tree trunks where nests develop whereas tree-hugger larvae are found on Blakella tessellaris, egg masses are laid in the outer canopy, and nests develop on the trunk or large branches. Of the 47 egg masses of O. lunifer transplanted to the unnatural host, only one cohort of tree-hugger larvae developed through to adult moths. Placing an egg mass in its unnatural position on its natural host did not prevent the larvae from developing and successfully establishing nests for either nesting-form, although all the ground-nesters moved position (from the canopy to the ground) and the tree-huggers mostly did not (from the ground to the canopy). Only the tree-hugger form of O. lunifer developed a viable nest on the unnatural host species, established a nest at the unnatural oviposition site, and shared that nest with larvae of the other nesting-form, suggesting tree-hugger larvae are somewhat plastic in their behaviour and ecology. Our findings add to previous studies indicating that Acacia is likely the ancestral host of O. lunifer though large areas of its range remain unstudied.

There are difficulties in tracking host use by pests and mating between pests exposed to Bt selection and non-Bt hosts across landscapes. We used stable isotope analyses of sampled bulked and individual Helicoverpa armigera moths across the major cotton producing area of northwestern China to estimate contributions made by the predominant crops, Bt cotton (C-3) and non-Bt corn (C-4; a putative refuge). 'Effective mating' that between moths originating from cotton and the putative refuge (corn) was estimated using the isotope signal of sampled females and their spermatophores. Across the 4 years (2012-2015), substantially fewer moths were produced from putative refuges versus Bt cotton, and an asynchrony in population phenology occurred in moths originating from both sources at certain critical times. The proportion of C-4 moths in bulked samples, and as individual females, was the highest during spring and autumn. Furthermore, the percentage of C-4 moths originating from corn was positively correlated with its percentage in the landscape. However, mating was biased toward pairs of moths originating from the same host type. The proportion of 'effective mating' ranged from 24 to 45%, and was greatest during spring and autumn correspondingly. Our study suggests that the refuge role of corn might be overestimated in northwestern China because asynchrony of population phenology and a bias in mating toward pairs of moths that originate from host type are not being considered. Therefore, increasing the diversity of refuge crops temporally would better facilitate resistance management instead of relying on a single refuge host.

As two major pests of cowpea in South China, bean flower thrips [Megalurothrips usitatus (Bagnall)] and flower thrips [Frankliniella intonsa (Trybom)] always occur on the same plant. In this study, the two-sex life table parameters of these two species were investigated on three bean pods: cowpea (Vigna unguiculata L. var. Chunqiu Wujiadou), snap bean (Phaseolus vulgaris L. var. Yonglong 3), and green bean (Phaseolus vulgaris L. var. Linghangzhe) using standard cut bean protocols. Longevity of female adult M. usitatus showed no significant difference on cowpea and snap bean, but was shortest on green bean, with the highest fecundity on snap bean, followed by cowpea and green bean. Longevity and fecundity of female adult F. intonsa were both highest on cowpea, followed by snap bean and green bean. On snap bean, the population parameters (R0, GRR, T) of M. usitatus were higher than F. intonsa, whereas r and λ were not different, suggesting that M. usitatus were more competitive on snap bean. On cowpea, the population parameters (R0, GRR, r, λ) of F. intonsa were higher than M. usitatus, suggesting a competitive advantage of F. intonsa on cowpea. To better mimic field conditions, we investigated the survival and fecundity of adult M. usitatus under two distinct scenarios: when they could feed directly on cut surfaces of cowpeas (standard lab protocol), and when they could not. Adult survival of M. usitatus is not significantly influenced by whether or not they fed directly on cut surfaces of cowpeas. However, a notable decrease in fecundity was observed in M. usitatus that fed on surface-covered cut pods. This suggested that direct feeding on cut surfaces of cowpea did have an impact on thrips’ fecundity, offering fresh perspectives for future research into the growth and development of thrips in a laboratory. Our study suggests that experiments involving cut surfaces may be misleading, and further investigations are ongoing to address these concerns.

Understanding how landscape composition and configuration drive the dynamics of pests and their various natural enemies is crucial to enhance biological control services (biocontrol). Geographic variability in landscape effects prompts questions about whether this is due to genuine differences or methodological differences among studies, given that most studies are conducted in a single region. This study investigated how the ecological function of parasitoids and predators responds to landscape traits in three regions encompassing an agriculture intensification gradient. The effects of landscape structure and configuration differed among regions and natural enemies. Non-crop habitats increased the abundance of parasitoids only in two less intensified regions presumably due to insufficient amount of non-crop habitats in the intensified region (typically < 10%). Nevertheless, their biological control efficiency (BCE) was consistently increased by non-crop habitats across regions. Higher maize proportion increased predator abundance and their BCE in the two nonmountainous regions. The value of maize as a source habitat for predators may have been limited in the mountainous region due to the lower aphid abundances there. Edge density positively affected abundances of predators and parasitoids, but only positively increased the BCE of all natural enemies combined. Inconsistent regional responses to the same landscape variables suggest that a uniform integrated pest management strategy for alfalfa is impractical. However, increasing edge density should be a useful first step for supporting diverse natural enemy communities and their biocontrol potential.

The Fall Armyworm, Spodoptera frugiperda (Lepidoptera, Noctuidae), is a serious migratory pest. After invading China in 2019, the species was established as a year-round breeding population in most of the southern provinces. The area of winter maize in this region has been increasing due to the huge demand of fresh maize consumption, which is potentially at risk from this invasive pest, although the growth and development of S. frugiperda in the region’s changing climate is unclear, particularly with rising temperatures at night. Here, we used the highest daytime temperatures of 27 °C, 24 °C, 20 °C and decreased these by 2, 4 and 6 °C to reflect the range of nighttime temperatures indicative of winter conditions in a warming climate to evaluate the effect of increasing night temperatures on the growth and development of S. frugiperda. Results show that the survival of larvae and pupae significantly declined with daytime temperatures declining and the nighttime temperature range increasing. Significant developmental effects were observed across all daytime–nighttime temperature treatments, except for adults. Additionally, there were significant interaction effects for all stages, except the egg stage, and generation time. The development rate increased with the increasing daytime temperatures and nighttime temperatures, except for the intermediate treatments (Group II). The uniformity of pupation and emergence times were higher under high daytime temperatures and nighttime temperature treatments. Predictions of FAW development and warnings to local farmers need to be adjusted to take into account the more rapid development when nighttime temperatures increase in the warming climate. These results will support decision makers in developing long-term management strategies for FAW in southern China.

>Insect pest damage to crops is a threat to global food security(Tilman et al.,2011).Climate change,the evolution of insecticide resistance,and the phasing out of insecticides due to environmental and safety concerns exacerbate this problem.Farmers urgently need safe and effective crop protection tools to sustainably generate yields that meet ever-increasing global demand.