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.

捕食性蝽类（异翅亚目：益蝽亚科，Heteroptera: Asopinae）可通过特化的口针注入唾液毒液以捕获猎物。然而，此前对其唾液毒液的蛋白质组成表征尚不充分，这极大阻碍了对该毒液功能的深入研究。本研究针对捕食性蝽类中华益蝽（Arma chinensis）的唾液毒液蛋白质组分展开了详细解析。我们通过多种方法从5龄若虫或成年雌性个体中采集了腺体提取物与毒液样品，并结合毒液腺体的转录组分析，对分泌的毒液开展了鸟枪法蛋白质组学（shotgun proteomic）检测。此外，我们通过注射采集得到的腺体提取物或毒液样品，评估了中华益蝽毒液对其猎物粘虫（Mythimna separata）幼虫的生物学效应。蛋白转录组学（proteotranscriptomic）分析结果显示，中华益蝽毒液包含一套复杂的蛋白质组，涵盖超过100种独立蛋白，包括氧化还原酶、转移酶、水解酶、连接酶、蛋白酶抑制剂、识别与转运结合蛋白、其他蛋白以及大量未表征蛋白。除未表征蛋白外，水解酶类构成了中华益蝽毒液中丰度最高的蛋白家族，涵盖毒液丝氨酸蛋白酶样蛋白、毒液S1蛋白酶、类胰蛋白酶、组织蛋白酶、磷脂酶A2、磷酸酶、核酸酶、α-淀粉酶与几丁质酶等。注射实验结果同样证实，中华益蝽唾液毒液中的蛋白质类组分对粘虫幼虫具有显著杀虫活性。本研究极大拓展了学界对捕食性异翅亚目昆虫唾液蛋白的认知，亦可为新型杀虫化合物的开发提供重要参考。