Many species of endoparasitoid wasps provide biological control services in agroecosystems. Although there is a great deal of information on the ecology and physiology of host/parasitoid interactions, relatively little is known about the protein composition of venom and how specific venom proteins influence physiological systems within host insects. This is a crucial gap in our knowledge because venom proteins act in modulating host physiology in ways that favor parasitoid development. Here, we identified 37 possible venom proteins from the polydnavirus-carrying endoparasitoid Cotesia chilonis by combining transcriptomic and proteomic analyses. The most abundant proteins were hydrolases, such as proteases, peptidases, esterases, glycosyl hydrolase, and endonucleases. Some components are classical parasitoid venom proteins with known functions, including extracellular superoxide dismutase 3, serine protease inhibitor and calreticulin. The venom contains novel proteins, not recorded from any other parasitoid species, including tolloid-like proteins, chitooligosaccharidolytic β-N-acetylglucosaminidase, FK506-binding protein 14, corticotropin-releasing factor-binding protein and vascular endothelial growth factor receptor 2. These new data generate hypotheses and provide a platform for functional analysis of venom components.

Parasitoid wasps are rapidly developing as a model for evolutionary biology. Here we present chromosomal genomes of two Anastatus wasps, A. japonicus and A. fulloi, and leverage these genomes to study two fundamental questions—genome size evolution and venom evolution. Anastatus shows a much larger genome than is known among other wasps, with unexpectedly recent bursts of LTR retrotransposons. Importantly, several genomic innovations, including Piwi gene family expansion, ubiquitous Piwi expression profiles, as well as transposable element-piRNA coevolution, have likely emerged for transposable element silencing to maintain genomic stability. Additionally, we show that the co-option evolution arose by expression shifts in the venom gland plays a dominant role in venom turnover. We also highlight the potential importance of non-venom genes that are coexpressed with venom genes during venom evolution. Our findings greatly advance the current understanding of genome size evolution and venom evolution, and these genomic resources will facilitate comparative genomics studies of insects in the future.

Habrobracon hebetor is a parasitoid wasp capable of infesting many lepidopteran larvae. It uses venom proteins to immobilize host larvae and prevent host larval development, thus playing an important role in the biocontrol of lepidopteran pests. To identify and characterize its venom proteins, we developed a novel venom collection method using an artificial host (ACV), i.e., encapsulated amino acid solution in paraffin membrane, allowing parasitoid wasps to inject venom. We performed protein full mass spectrometry analysis of putative venom proteins collected from ACV and venom reservoirs (VRs) (control). To verify the accuracy of proteomic data, we also collected venom glands (VGs), Dufour’s glands (DGs) and ovaries (OVs), and performed transcriptome analysis. In this paper, we identified 204 proteins in ACV via proteomic analysis; compared ACV putative venom proteins with those identified in VG, VR, and DG via proteome and transcriptome approaches; and verified a set of them using quantitative real-time polymerase chain reaction. Finally, 201 ACV proteins were identified as potential venom proteins. In addition, we screened 152 and 148 putative venom proteins identified in the VG transcriptome and the VR proteome against those in ACV, and found only 26 and 25 putative venom proteins, respectively, were overlapped with those in ACV. Altogether, our data suggest proteome analysis of ACV in combination with proteome–transcriptome analysis of other organs/tissues will provide the most comprehensive identification of true venom proteins in parasitoid wasps.

Background: A fundamental feature of parasitism is the nutritional exploitation of host organisms by their parasites. Parasitoid wasps lay eggs on arthropod hosts, exploiting them for nutrition to support larval development by using diverse effectors aimed at regulating host metabolism. However, the genetic components and molecular mechanisms at the basis of such exploitation, especially the utilization of host amino acid resources, remain largely unknown. To address this question, here, we present a chromosome-level genome assembly of the parasitoid wasp Cotesia chilonis and reconstruct its amino acid biosynthetic pathway. Results: Analyses of the amino acid synthetic pathway indicate that C. chilonis lost the ability to synthesize ten amino acids, which was confirmed by feeding experiments with amino acid-depleted media. Of the ten pathways, nine are known to have been lost in the common ancestor of animals. We find that the ability to synthesize arginine was also lost in C. chilonis because of the absence of two key genes in the arginine synthesis pathway. Further analyses of the genomes of 72 arthropods species show that the loss of arginine synthesis is common in arthropods. Metabolomic analyses by UPLC-MS/MS reveal that the temporal concentrations of arginine, serine, tyrosine, and alanine are significantly higher in host (Chilo suppressalis) hemolymph at 3 days after parasitism, whereas the temporal levels of 5-hydroxylysine, glutamic acid, methionine, and lysine are significantly lower. We sequence the transcriptomes of a parasitized host and non-parasitized control. Differential gene expression analyses using these transcriptomes indicate that parasitoid wasps inhibit amino acid utilization and activate protein degradation in the host, likely resulting in the increase of amino acid content in host hemolymph. Conclusions: We sequenced the genome of a parasitoid wasp, C. chilonis, and revealed the features of trait loss in amino acid biosynthesis. Our work provides new insights into amino acid exploitation by parasitoid wasps, and this knowledge can specifically be used to design parasitoid artificial diets that potentially benefit mass rearing of parasitoids for pest control.

Insects are susceptible to elevated temperatures, resulting in impaired fertility, and shortened lifespan. This study investigated the genetic mechanisms underlying heat stress effects. We conducted RNA sequencing on Pteromalus puparum exposed to 25°C and 35°C, revealing transcriptional signatures. Weighted Gene Co-expression Network Analysis uncovered heat stress-associated modules, forming a regulatory network of 113 genes. The network is naturally divided into two subgroups, one linked to acute heat stress, including heat shock proteins (HSPs), and the other to chronic heat stress, involving lipogenesis genes. We identified an Xap5 Heat Shock Regulator (XHSR) gene as a crucial network component, validated through RNA interference and quantitative PCR assays. XHSR knockdown reduced wasps' lifespan while directly inducing HSPs and mediating lipogenesis gene induction. CRISPR/Cas9-mediated knockout of the Drosophila XHSR homolog reduced mutants' survival, highlighting its conserved role. This research sheds light on thermal tolerance mechanisms, offering potential applications in pest control amid global warming.

The order Hymenoptera includes a large number of species with diverse lifestyles and is known for its significant contributions to natural ecosystems. To better understand the evolution of this diverse order, we performed large-scale comparative genomics on 131 species from 13 superfamilies, covering most representative groups. We used these genomes to reveal an overall pattern of genomic change in terms of gene content and evolutionary rate throughout hymenopteran history. We identified genes that possibly contributed to the evolution of several key innovations, such as parasitoidism, wasp-waist, stinger, and secondary phytophagy. We also discovered the distinct genomic trajectories between the clade containing major parasitoid wasps (Parasitoida) and stinging species (Aculeata) since their divergence, which are involved in many aspects of genomic change, such as rapidly evolving gene families, gene gain and loss, and metabolic pathway evolution. In addition, we explored the genomic features accompanying the three independent evolution of secondary phytophagy. Our work provides insights for understanding genome evolution and the genomic basis of diversification in Hymenoptera.