Insects

Entomopathogenic fungi are a promising tool for the biological control of crop pests provided low or no impact on non-target organisms. Selection for host specificity as well as on-target applications open new avenues for more sustainable strategies for pest management. Isolates of Metarhizium anisopliae (Metschn.) Sorokin have been identified as promising for developing innovative entomovectoring-based strategies for the control of the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), in Africa. To be effective, this technology requires high strain virulence at a low number of spores, but sufficient incubation time to allow transmission to wild conspecifics. This depends on trophic interactions between the host and the pathogen, which are mediated by abiotic factors. In the present study, we investigated the virulence of the Met69 strain against adult flies, depending on the inoculation dose, air temperature and formulation. High pathogenicity was observed at very low inoculation doses (LT50 of 4.85 days with 6100 spores per fly) independently of fly sex. Virulence increased with spore load in a tight range (5600 and 6100 spores per fly) and with air temperature observed in the field (20-28{degrees}C). Unexpectedly, corn starch used as an adjuvant to increase the carrying capacity of insects decreased the virulence of the pathogen. The results will help improve area-wide control strategies based on the contamination of wild flies through auto-inoculation devices or interactions with released mass-reared sterile males coated with fungal spores. Furthermore, the study proposes an approach for calibrating area-wide control strategies, taking into account both the insect and pathogen bioecology and the environment in which they evolve. Author rolesAnais Chailleux: Conceptualization, Funding acquisition, Methodology, Data curation, Writing - original draft. Oumou Noumou Coulibaly: Investigation, Writing - original draft. Babacar Diouf: Investigation, Visualization. Samba Diop: Investigation. Ahmad Sohel: Resources, Writing - review & editing. Thierry Brevault: Conceptualization, Funding acquisition, Project administration, Writing - review & editing.

Social insect colonies are known to be targeted by a wide variety of different parasites and pathogens because of their high host abundance. However, within a colony, the level of risk to exposure could vary among individuals depending on their role. Unlike many known parasites, which mostly target specific groups of individuals, e.g. foragers, the myrmecoparasitic fungus Rickia wasmannii infects entire ant colonies, being linked to subtle changes in physiology, morphology and behaviour. We investigated how different groups within the colonies respond to being exposed to the fungus by measuring the expression of the genes defensin 1 and prophenoloxidase, both vital components of ant immunity. We found that workers, queens and broods varied in their immune response. Workers displayed diverse profiles, with variable responses to infection: in same-age workers, both prophenoloxidase and defensin 1 levels exhibited increases in correlation with pathogen loads. Queens exhibited a more pronounced immune response. Highly infected queens had a heightened immune response. Larvae did not show a discernible response. Morphological and physiological characteristics had limited effects on gene expression, except in the case of queens, where larger individuals displayed higher defensin 1 expression. Our study shows that these divergent responses likely stem from the differing physiological needs and priorities of various groups within the colony. HighlightsO_LIIn same-age workers, prophenoloxidase and defensin 1 levels increased with pathogen loads. C_LIO_LIBody size affected defensin 1 expression in a caste-specific manner: larger queens displayed higher expression. C_LIO_LIInfection did not elicit any specific response in larvae. C_LIO_LIThe diverse response to infection likely arise from distinct physiological needs and priorities within colony groups. C_LI

1. BackgroundParasitoid-host interactions are key drivers of insect community structure, with host concealment influencing parasitoid diversity and parasitism rates. However, the effectiveness of different host defense strategies against parasitoids remains insufficiently understood. 2. ObjectiveThis study examines how host concealment level affects parasitoid communities and parasitism rates in two microlepidopteran species developing on hops (Humulus lupulus L.), Caloptilia fidella and Cosmopterix zieglerella, which employ leaf-rolling and leaf-mining strategies, respectively. 3. MethodsWe combined morphological identification with molecular species delimitation using ITS2 and CO1 markers and applied ASAP and bPTP methods to refine parasitoid taxonomy and detect cryptic species. 4. ResultsSemi-concealed C. fidella larvae in leaf rolls experienced significantly higher parasitism than their mining stages, whereas fully concealed C. zieglerella had lower parasitism rates. Molecular analyses confirmed the idiobiont strategy in Sympiesis acalle, S. sericeicornis, and Elachertus fenestratus, and bPTP proved more sensitive in detecting cryptic species than ASAP. 5. SignificanceThese findings demonstrate that semi-concealed hosts face a higher risk of parasitism than fully concealed hosts, suggesting that leaf-mining provides better protection than leaf-rolling in studied hosts. The study also highlights the power of molecular tools in species delimitation, emphasizing their importance for refining parasitoid taxonomy and advancing our understanding of host-parasitoid interactions.

Feeding experiments are standard tools in the pollinator risk assessment. The design (Oomen et al 1992) was developed to test insect growth regulators and herbicides. In recent years there was an update (Luckmann & Schmitzer 2015) on the outline in order to also focus on the advantage of different rates making a dose response design possible where exposure levels are known. Additionally, this design gives the possibility to test different rates for honey bee colonies foraging in the same landscape. The main objective of the experiment presented here was to determine the natural variability of foragers losses of hives fed with a sub-lethal neonicotinoid concentration compared to an untreated control. Other objectives were to see if the neurotoxic exposure results in any observable sub-lethal effects and to find out if losses can be correlated to hive development. This was assessed with traditional methods and a novel, visual monitoring device.

Aphid parasitoids (Hymenoptera; Aphidiidae) were surveyed within grain production landscapes in Victoria, Australia between 2017 and 2018, as well as more sporadically nationwide between 2016 and 2019. In addition, aphidiine records were collated from insect depositories around Australia and online databases. The 5551 specimens recorded constituted a total of 23 species and seven genera. Diaeretiella rapae (MIntosh) was the most common species, representing more than 70% of all aphidiines recorded. This species also showed a greater northerly geographic range than other aphidiines. During sampling between 2017 and 2019, aphidiines were reared from mummies to ascertain host-parasitoid relationships. Diaeretiella rapae was again the most commonly reared parasitoid, although aphidiine preference varied with aphid host and between states and territories. An illustrated dichotomous key to Australian aphidiines in grain production landscapes is provided for the 11 species sampled in our field surveys. This is the first comprehensive review of aphidiines sampled within Australia in over two decades. Knowledge about the diversity and distribution of these parasitoids is important for understanding their impact on current and future invasions of aphid species. In addition, understanding the interactions between grain aphids and their associated parasitoids will further support the inclusion of parasitoid wasps into integrated pest management (IPM) strategies.

Strains of Euschistus heros (Hemiptera: Pentatomidae) with resistance to thiamethoxam (NEO) and lambda-cyhalothrin (PYR), generated by selection with these insecticides in the laboratory, have been recently reported in Brazil. However, the mechanisms conferring resistance to these insecticides in E. heros remain unresolved. We utilized comparative transcriptome profiling and single nucleotide polymorphism (SNP) variant calling of susceptible and laboratory-selected resistant strains of E. heros to investigate the molecular mechanism(s) underlying resistance. The E. heros transcriptome was assembled using approximately 190.1 million paired-end reads, which generated 91,673 transcripts with a mean length of 720 bp and N50 of 1795 bp. Approximately, 54.8% of the assembled transcripts ware functionally annotated against the NCBI nr database, with most sequences (43%) being similar to the pentatomids Halyomorpha halys (43%) and Nezara viridula (29%). Comparative gene expression analysis between the susceptible (SUS) and NEO strains identified 215 significantly differentially expressed (DE) transcripts. DE transcripts associated with the metabolism of xenobiotics were all up-regulated in the NEO strain. The comparative analysis of the SUS and PYR strains identified 204 DE transcripts, including an esterase (esterase FE4), a glutathione-S-transferase, an ABC transporter (ABCC1), and aquaporins that were up-regulated in the PYR strain. We identified 9,588 and 15,043 non-synonymous SNPs in the PYR and NEO strains respectively in comparisons with the SUS strain. One of the variants (D70N) detected in the NEO strain occurs in a subunit (5) of the nicotinic acetylcholine receptor, the target-site of neonicotinoid insecticides. Nevertheless, the position of this residue was found very variable among 5 from insect species. In conclusion, neonicotinoid and pyrethroid resistance in laboratory-selected strains of E. heros is associated with a potential metabolic resistance mechanism mediated by the overexpression of several proteins commonly involved in the three phases of xenobiotic metabolism. Together these findings provide insight into the potential basis of resistance in E. heros and will inform the development and implementation of resistance management strategies against this important pest. HighlightsO_LI419 DE genes were observed in E. heros insecticide-resistant strains C_LIO_LI24,631 SNPs were identified in E. heros insecticide-resistant strains C_LIO_LIE. heros insecticide-resistant strains overexpress metabolic resistance genes C_LIO_LILambda-cyhalothrin-resistant E. heros overexpresses cuticular proteins C_LIO_LIThiamethoxam-resistant E. heros carries the target-site mutation D70N in nAChRalpha5 C_LI

The microcaddisfly family Hydroptilidae is the most species-rich within the insect order Trichoptera and has a global distribution. The taxonomy and systematics of this group remains understudied in proportion to its diversity. Here, we present a phylogenetic assessment of subfamily relationships that includes five of the six Hydroptilidae subfamilies (Hydroptilinae, Leucotrichiinae, Ochrotrichiinae, Orthotrichiinae, and Stactobiinae) using publicly available molecular data. Our analyses recovered Leucotrichiinae, Ochrotrichiinae, and Stactobiinae as monophyletic and Hydroptilinae as paraphyletic. Based on the diversity and distribution of taxa, much more representation of species is needed to fully understand the relationships of subfamilies; however, our results suggest a need to revisit the placement of Ithytrichia, which concurs with other recent molecular work on Hydroptilidae. Further clarity into the relationships of Hydroptilidae will be important for understanding the variability and phylogenetic signal of ecological traits.

The global application of Transeius montdorensis (Acari: Phytoseiidae) as a biological control agent across various protected crops has proven effective against a range of insect pests like thrips and whiteflies, as well as pest mites like broad mites and russet mites. Optimization of rearing T. montdorensis under laboratory conditions is crucial for further studies of this species to improve their application in Integrated Pest Management (IPM) programs. Here, we evaluated the development and reproduction of T. montdorensis when fed on four different diets, including cattail pollen (Typha latifolia), living dried fruit mites (Carpoglyphus lactis), frozen C. lactis eggs, and a mixed diet of frozen C. lactis eggs and T. latifolia pollen. Females consuming the mixed diet exhibited superior total fecundity and daily oviposition rate, along with the highest intrinsic rate of increase (rm) and net productive rate (R0) among all diets tested. The immature period was significantly longer for mites on a diet of living C. lactis compared to those on other diets. Importantly, utilizing frozen C. lactis eggs and T. latifolia pollen mitigates the risk of infestation and contamination from the living dried fruit mites, which is important for laboratory and field settings when releasing the predator colonies. Our findings not only present an optimized rearing method for predatory mites under laboratory conditions but also suggest potential broader applications for enhancing the effectiveness and sustainability of biological control strategies across various agroecosystems and reducing dependency on chemical pesticides.

Biological invasions are an increasing threat to ecosystems; early identification of invasive species and rigorous monitoring are prerequisites to minimize environmental damage. Currently, two large hymenopterans of Asian origin are spreading across Europe: the yellow-legged hornet Vespa velutina nigrithorax Buysson, 1905 and the giant resin bee Megachile sculpturalis Smith, 1853, populations of which have been gradually being discovered across Europe since 2004 and 2008, respectively. Considering the current distribution of both species in Europe, further spread through Central Europe is expected in recent years. In July 2024, the first record of M. sculpturalis was documented in Slovakia, followed by more reports from 11 localities. Less than two months later, the second invasive hymenopteran, V. velutina nigrithorax, was also detected. Utilising multiple methods, their nest was discovered as well. On-site observations showed that the yellow-legged hornets (workers) were active almost two days after colony eradication. The finding of both species was accompanied by an intensive campaign using citizen science.

BackgroundBiological control is a sustainable strategy to combat agricultural pests. Yet, due to legislation, importing non-native biocontrol agents is increasingly restricted. Thus, selective breeding of biocontrol traits of native species is suggested to enhance performance of existing biocontrol agents. Genomic prediction is a new alternative to exploit genetic variation for improving biocontrol efficacy. This study aims to establish proof-of-principle for genomic prediction in insect biocontrol agents, using wing morphology traits in the parasitoid Nasonia vitripennis Walker (Pteromalidae) as a model. MethodsWe performed genomic prediction using a Genomic Best Linear Unbiased Prediction (GBLUP) model, using a total of 1,230 individuals with 8,639 SNPs generated by genotyping-by-sequencing (GBS). We used individuals from two generations from the outbred HVRx population, 717 individuals from generation G169 and 513 from generation G172. To assess genomic prediction accuracy, we used across- generation validation: forward validation for G172 from G169, backward in time validation for G169 from G172, and also 5-fold cross-validation, randomly using one fifth of the population as validiation and the others as training groups. ResultsFor size-related traits, including tibia length, wing length, width, and second moment wing area, the accuracy of genomic prediction was close to zero in both across-generation validations, but much higher in 5-fold cross-validation (ranging 0.54-0.68). For the shape-related trait wing aspect ratio, a high accuracy was found for all three validation strategies, with 0.47 for across-generation forward validation, 0.65 for across-generation backward validation, and 0.54 for 5-fold cross-validation. ConclusionPromising accuracies were observed for all traits in 5-fold cross-validation, but not in the across-generation validations. Overall, applying genomic selection in insect biocontrol agents with a relative small effective population size seems promising. However, factors such as the biology of insects, the techniques of phenotyping, and costs of large-scale genotyping still challenge the application of genomic selection to biocontrol agents.

Fungus farming insects encounter multiple microbial threats in their cultivar gardens. They can affect both the nutritional cultivar and the insects health. In this study, we explored the potential of ambrosia beetles and their larvae to detect the presence of ubiquitous weed or entomopathogenic fungi. The ability to recognize a threat offers individuals a chance to react. Our study organism, the fruit-tree pinhole borer, Xyleborinus saxesenii, is associated with two mutualistic fungi, Dryadomyces sulphureus (Raffaelea sulphurea) and Raffaelea canadensis. Both symbionts were tested in combinations with two common fungus-garden weeds (Aspergillus sp. and Penicillium commune) and the entomopathogen Beauveria bassiana in two-choice experiments. Behavioural repellence was found in many, but not all combinations. Larvae and adult females showed an opposite reaction towards the entomopathogen, whereas for Aspergillus sp., neither provoked repellence nor attraction of larvae and adult females, if R. canadensis was used as lure. Our results validate a response of both larvae and adult ambrosia beetles towards other fungal volatiles. Their decision to confront a potential threat or preferably to avoid it could be subject to a more complex context.

BACKGROUNDThe oriental fruit fly Bactrocera dorsalis is an invasive pest causing considerable ecological and economic damage worldwide. The Y chromosome is an important target for the sterile insect technique (SIT) but its sequence and structure has been poorly explored. RESULTSWe assembled the genome of B. dorsalis at the chromosome level with a total size of 562.6 Mb. The assembly includes a [~]7.6 Mb Y chromosome sequence, being the first reported Y chromosome in Tephritidae. The assembled Y chromosome is highly repetitive, and contains 61 genes, including 9 multi-copy genes. We surprisingly found that the M factor (MoY) in Tephritidae has multiple copies, verified by our droplet digital PCR (ddPCR) analysis. Besides, we identified 32 copies of gyf-like on the Y chromosome (gyfY) that were highly expressed in testis. RNAi targeting the gyfY resulted in depletion of live sperms, suggesting that the amplification of gyfY is essential for male fertility, which facilitated the understanding of high fecundity of this invasive insect. CONCLUSIONWe reported firstly the Y chromosome of Bactrocera dorsalis. Our results will also provide target genes for CRISPR/Cas9 based SIT, leading to the development of novel control strategies against tephritid flies.

Carrion insects need to quickly and accurately locate a suitable carcass to maximize their reproductive success. They are attracted by cadaveric volatile organic compounds (VOCs). However, very little is known about VOCs that attract insects at later stages of carrion decomposition. Here, we tested the response of Necrodes littoralis (Linnaeus, 1758). (Staphylinidae: Silphinae), a Palearctic beetle that colonizes large carrion late in decomposition, to selected VOCs. First, in the laboratory choice tests we demonstrated that the beetles reveal no preference for meat with larval blow flies over meat alone. This finding indicates that both, the fly larvae and the feeding matrix they form on meat are not the source of specific attractants for the adult beetles of Necrodes Leach, 1815. Therefore, we focused on VOCs that are related to carrion putrefaction. We tested the response of the beetles to benzyl butyrate, butan-1-ol, butyric acid, cadaverine, dimethyl disulfide (DMDS), dimethyl trisulfide, indole, phenol, putrescine and skatole in laboratory choice assays and field trapping tests. None of the compounds elicited the positive and significant response of the beetles under laboratory or field conditions, indicating that these VOCs are probably not the attractants of N. littoralis. Moreover, in the field tests we found a significant attraction of Lucilia sericata (Meigen, 1826) (Diptera: Calliphoridae) to traps with DMDS. DMDS revealed also a positive (however insignificant) response of Saprinus spp. (Coleoptera: Histeridae) and Sarcophaga spp. (Diptera: Sarcophagidae). Sarcophaga flies were also attracted to traps with butyric acid. These findings expand the knowledge on chemoecology of carrion insects, highlighting the need to further search for VOCs that attract late-colonizers of carrion.

The spider mites Tetranychus evansi Baker & Pritchard and Tetranychus urticae Koch (Acari: Tetranychidae) are key tomato pests worldwide. Biological control of spider mites using phytoseiid predatory mites remains challenging. The glandular trichomes on the tomato leaves and stem severely hamper the movement and establishment of the predatory mites. As a result, smaller predatory mites, able to thrive under the sticky heads of the glandular trichomes, have gained much interest. As some iolinid predatory mites were reported to feed on spider mites, we investigated the potential of Pronematus ubiquitus McGregor to control both T. urticae and T. evansi on tomato plants. On whole tomato plants, P. ubiquitus was able to suppress populations of T. urticae, but not of T. evansi. Based on the marginal number of spider mites killed in laboratory trials, the observed biocontrol effect on full tomato plants might not be due to direct predation but to a plant-mediated indirect impact. The oviposition of T. urticae was found to be significantly lower on tomato leaflets pre-exposed to P. ubiquitus as compared to non-exposed leaflets. The oviposition rate of T. evansi was not affected by previous exposure of the tomato host plant to P. ubiquitus. We demonstrated that P. ubiquitus reduces the population growth of T. urticae on tomato plants. Further large-scale field trials need to confirm the findings of the present study.

Oviposition behavior in phytophagous insects is influenced by different stimuli and plays a key role in pest dynamics and crop loss. This study used 3D-printed artificial fruits varying in colour (yellow, blue, white) and odour (cherry, orange, banana) to test how visual and olfactory cues affect oviposition acceptance (no-choice) and preference (choice). In no-choice assays, the nine artificial fruits displayed sufficiently different visual and olfactory cues to trigger different egg-laying outputs (by a factor 1:3 between the least attractive fruit, white fruit with banana scent and the most attractive fruit, yellow fruit with cherry scent). While cues acted independently in no-choice settings, significant interactions were observed in choice conditions, highlighting multimodal sensory integration. In choice assays, the number of eggs laid and female preference depended on both the characteristics of fruits and their context. However a strong correlation was found between acceptance and preference. The relationship found between acceptance and preference implied that when a fruit seemed preferred in no-choice assays, it was even more preferred in one-choice assays. We finally discussed the practical implications for behavior-based pest management strategies.

SUMMARYClimate change is reshaping agriculture and insect biodiversity worldwide. With rising temperatures, insect species with narrow thermal margins are expected to be pushed beyond their thermal limits, and losses related to herbivory and diseases transmitted by them will be experienced in new regions. Several previous studies have investigated this phenomenon in tropical and temperate regions, locally and globally; however, here, it is proposed that climate changes impact on agriculture can be traced through the study of Nearctic migratory insects, specifically leafhoppers. To test this hypothesis, leafhoppers in strawberry fields located in the province of Quebec, eastern Canada, were evaluated. The strawberry-leafhopper pathosystem offers a unique opportunity because leafhoppers can transmit, among other diseases, strawberry green petal disease (SbGP), which is associated with pathogenic phytoplasmas. Here, we found that in the last ten years, the number of leafhoppers has been increasing in correspondence with the number of SbGP cases detected in eastern Canada, reporting for the first time ten species new to eastern Canada and two to the country, although the leafhopper diversity has been seriously affected. Our model using more than 34 000 leafhoppers showed that their abundance is influenced by temperature, a factor that we found also influences the microbiome associated with Macrosteles quadrilineatus, which was one of the most abundant leafhoppers we observed. One of our most striking findings is that none of the insecticides used by strawberry growers can control leafhopper incidence, which could be linked to microbiome changes induced by changing temperatures. We suggest that Nearctic leafhoppers can be used as sentinels to trace the multilayered effects of climate change in agriculture. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=185 SRC="FIGDIR/small/544773v1_ufig1.gif" ALT="Figure 1"> View larger version (77K): org.highwire.dtl.DTLVardef@e984eorg.highwire.dtl.DTLVardef@3146a9org.highwire.dtl.DTLVardef@1160b9aorg.highwire.dtl.DTLVardef@53c39c_HPS_FORMAT_FIGEXP M_FIG C_FIG IN BRIEFThe current climate crisis is reshaping insect biodiversity and abundance, but little is known about the direct effect of this phenomenon on agriculture. In this study, we explored leafhoppers, a group of agriculturally important insect pests and disease vectors, as sentinels of the effect of climate change on agriculture. Our findings indicate that this group of insects can help us to understand the effect of the current climate crisis on insect invasions, diversity, abundance, disease dynamics and insecticide resistance and to take quick action to ensure food security while achieving more sustainable agriculture. HIGHLIGHTSO_LIMigratory leafhoppers benefit from temperature increases C_LIO_LILeafhopper-transmitted diseases have increased in the last decade C_LIO_LINew non-migratory leafhoppers can be found now in Nearctic regions C_LIO_LILeafhopper insecticide resistance could be linked to the insect microbiome C_LI

The ability of powered flight in insects facilitated their great evolutionary success allowing them to occupy various ecological niches. Beyond this primary task, wings are often involved in various premating behaviors, such as the generation of courtship songs and the initiation of mating in flight. These specific functions imply special adaptations of wing morphology, as well as sex-specific wing morphologies. Although wing morphology has been extensively studied in Drosophila melanogaster, a comprehensive understa nding of sexual wing shape dimorphisms and developmental plasticity is missing for other Diptera. Therefore, we raised flies of the three Diptera species Drosophila melanogaster, Ceratitis capitata and Musca domestica at different environmental conditions and applied geometric morphometrics to analyze wing shape. Our data showed extensive interspecific differences in wing shape, as well as a clear sexual wing shape dimorphism in all three species. We revealed an impact of different rearing temperatures wing shape in all three species, which was mostly explained by plasticity in wing size in D. melanogaster. Rearing densities had significant effects on allometric wing shape in D. melanogaster, while no obvious effects were observed for the other two species. Additionally, we do not find evidence for sex-specific response to different rearing conditions in all three species. We determined species-specific and common trends in shape alterations, and we hypothesize developmental and functional implications of our data. Contribution to the Field StatementThe size and shape of organisms and organs must be tightly controlled during development to ensure proper functionality. However, morphological traits vary considerably in nature contributing to phenotypic diversity. Such variation can be the result of evolutionary adaptations as well as plasticity for example as reaction to changing environmental conditions during development. It is therefore a major aim in Biology to unravel the processes that control differences in adult morphology. Insect wings are excellent models to study how organ size and shape evolves because they facilitate basic tasks such as mating and feeding. Accordingly, a tremendous variety of wings sizes and shapes evolved in nature. Additionally, plasticity in wing morphology in response to different rearing conditions has been observed in many insects contributing to phenotypic diversity. In this work we applied Geometric Morphometrics to study wing shape in the three Diptera species: the Mediterranean fruit fly Ceratitis capitata, the Vinegar fly Drosophila melanogaster and the housefly Musca domestica. Flies were raised in different temperature and density regimes that allowed us to study the effects of these environmental factors on wing shape. Additionally, in accordance with different mating behaviors of these flies, we observed a clear sexual shape dimorphism in all three species. Since the three studied species represent serious pests and disease vectors, our findings may contribute to existing and future monitoring efforts.

Males respond to intense sperm competition by adapting reproductive strategies to promote fertilization success, which is critical for population reproduction. Thus, investigating the patterns and mechanisms of sperm competition is crucial for the development and application of pest population management techniques. In this study, we analyzed the sperm precedence pattern of a major pest, the fall armyworm, and used this pattern to manage the pest population. First, we found that females had a post-mating response and did not gain direct benefit through multiple mating. Next, in a double mating experiment, we used a molecular marker created by CRISPR/Cas9 to determine that most females use only the sperm of the first male to produce offspring. To further explore the role of fertilizing sperm in sperm competition, we constructed a sterile male line with eupyrene sperm defect by knocking out the B2t gene. Interestingly, two round mating assays showed that first mating with B2t-null males inhibited sperm fertilization from a second wild-type male. In other words, prior mating with B2t-null males significantly reduced the fertility and fecundity of females. Based on this finding, we continued to explore whether sperm-deficient sterile males could be used in the management of FAW populations. Cage experiments and mathematical modeling analyses showed that the release of excess B2t-null males induced population suppression. Our study expands our knowledge of sperm competition patterns in lepidopteran. In addition, our study provides a paradigm to develop and apply genetic control methods based on sperm competition outcome in polyandrous pests. SignificanceSperm competition is essential for maintaining population reproduction. Understanding patterns and mechanisms of sperm competition facilitates the development of appropriate pest genetic control methods. Here, we describe that a globally major pest, the fall armyworm displays the first-male sperm precedence pattern. Interestingly, first mating with B2t-null males, which produces non-functional eupyrene sperm, significantly reduces the fertility and fecundity of females. That means that the ejaculate of the first male, even if its eupyrene sperm are defective, can inhibit sperm fertilization from a second wild-type male. Based on this, the release of excess B2t-null males significantly suppresses FAW populations. These results suggest that future development of genetic control techniques based on targeting nucleated sperm can effectively control FAW populations.

Sandy pitfall traps are an elaborate construction to capture prey and antlions are well-known representatives of this predation technique. From a soil mechanical perspective, antlions exploit the interactions between the particles of their habitat and engineer a stable trap. This construction is close to the unstable state, where a prey item will immediately slide towards the center - towards the ambushing antlion - when accidently entering the trap. This method is efficient, but requires permanent pit maintaining. According to the present knowledge, antlions throw sand at their prey, to distract it, and/or cause sand slides towards the center of the pit. Using sand throwing and escape experiments, as well as finite element analysis, we supported this hypothesis. Furthermore, we added new hypothesis about maintaining the pitfall trap. We showed that sand that accumulates in the center of the pit will be continuously removed, which lead to the slope maintenance close to an unstable condition. This avoids self-burial of the antlion, as well as decreasing the chance of prey item escapes by keeping the slope angle steep. This demonstrates the interaction of an insect larva with its abiotic environment from a novel perspective and adds further insights into longstanding entomological hypotheses.

Insect-induced galls are novel structures that serve as habitat to whole communities of associate arthropods that include predators, parasitoids and inquilines. Galling insects are generally under-described, but their associate communities, which can include many specialist organisms, are virtually unknown, particularly in the southwest United States. Aciurina bigeloviae (Cockerell 1890) and Aciurina trixa Curran 1932 are unusually common and abundant galling flies in New Mexico. The 2 species are sister and occur in sympatric areas but have distinct gall morphologies. We reared all arthropods from 3800 galls from 14 sites in the northern and central regions of the state and as a result characterized the complete communities of both species, including barcode sequences and eclosion phenology. We also investigate interactions of A. trixa galls with the abundant inquiline weevil Anthonomus cycliferus Fall 1913 and find no measurable effect of inquiline abundance on the size of the emerged adult fly or gall. The total species count is 24 and includes 6 guilds; both A. bigeloviae and A. trixa communities are richer and more complex than other documented Tephritidae-Asteraceae galling systems. This study highlights the potential of galling insects as ecosystem engineers to maintain large, rich and multi-trophic communities.