Proteinaceous compounds in the stink bug Arma chinensis (Hemiptera: Pentatomidae) salivary venom are lethal to Mythimna separata larvae
Predacious pentatomids (Heteroptera: Asopinae) capture prey by injecting salivary venom using their specialized stylets. However, the proteinaceous constituents of their salivary venom were poorly characterized, which impeded further understanding of the function of the venom. In this study, we described the protein components of the salivary venom of the predatory stink bug Arma chinensis in detail. We collected gland extracts and venom samples from 5th-instar nymphs or adult females using various methods and performed shotgun proteomic detection of the secreted venom combined with transcriptomic analyses of the venom glands. Furthermore, we evaluated the biological effect of the A. chinensis venom on its prey, Mythimna separata larvae, by injecting the collected gland extracts or venom samples. The results of the proteotranscriptomic analysis showed that the venom of A. chinensis includes a complex suite of over a hundred individual proteins, comprising oxidoreductases, transferases, hydrolases, ligases, protease inhibitors, recognition, transport and binding proteins, other proteins, and many uncharacterized proteins. Besides of uncharacterized proteins, hydrolases, such as venom serine protease-like, venom S1 protease, trypin-like protease, cathepsin, phospholipase A2, phosphatase, nuclease, alpha-amylase, and chitinase, constitute the most abundant families in A. chinensis venom. The injection assay also indicated the potency of the proteinaceous compounds in A. chinensis salivary venom against M. separata larvae. Our work greatly expands the knowledge of salivary proteins in predaceous heteropterans and may contribute to the development of novel insecticidal compounds.