RESUMO
Predatory stink bugs capture prey by injecting salivary venom from their venom glands using specialized stylets. Understanding venom function has been impeded by a scarcity of knowledge of their venom composition. We therefore examined the proteinaceous components of the salivary venom of the predatory stink bug Arma custos (Fabricius, 1794) (Hemiptera: Pentatomidae). We used gland extracts and venoms from fifth-instar nymphs or adult females to perform shotgun proteomics combined with venom gland transcriptomics. We found that the venom of A. custos comprised a complex suite of over a hundred individual proteins, including oxidoreductases, transferases, hydrolases, ligases, protease inhibitors, and recognition, transport and binding proteins. Besides the uncharacterized proteins, hydrolases such as venom serine proteases, cathepsins, phospholipase A2, phosphatases, nucleases, alpha-amylases, and chitinases constitute the most abundant protein families. However, salivary proteins shared by and unique to other predatory heteropterans were not detected in the A. custos venom. Injection of the proteinaceous (>3 kDa) venom fraction of A. custos gland extracts or venom into its prey, the larvae of the oriental armyworm Mythimna separata (Walker, 1865), revealed insecticidal activity against lepidopterans. Our data expand the knowledge of heteropteran salivary proteins and suggest predatory asopine bugs as a novel source for bioinsecticides.
RESUMO
Trichogramma spp. are egg parasitoids largely used worldwide for biological control of lepidopteran pests. Host quality (related to host size and age, host species, etc.) can influence parasitism preference and fitness of the parasitoid offspring. However, few studies have documented the performance of Trichogramma parasitoids when they parasitize nonfertilized eggs of their lepidopteran hosts. In the present study, we investigated the performance of three indigenous Trichogramma species ( Trichogramma japonicum Ashmead, Trichogramma dendrolimi Matsumura, and Trichogramma chilonis Ishii) on fertilized and nonfertilized eggs of their native host, Chilo suppressalis (Walker). The results showed that the three Trichogramma species tested could recognize fertilized and nonfertilized eggs of C. suppressalis . The different fertilization status eggs of C. suppressalis were all accepted by T. japonicum , T. chilonis , and T. dendrolimi with a clear tendency that they preferred to parasitize fertilized eggs whether under no-choice or choice conditions. All Trichogramma species successfully completed development in parasitized eggs of C. suppressalis regardless if the host eggs were fertilized or not. There was similar adult emergence rate, development time, and female progeny between fertilized and nonfertilized eggs for all Trichogramma species with an exception of development for T. chilonis . Trichogramma chilonis had shorter developmental time in fertilized eggs than in nonfertilized ones. Whether in fertilized or nonfertilized eggs, T. dendrolimi had longer development time than other two Trichogramma species. However, T. dendrolimi had the largest percentage of female progeny on fertilized eggs, followed by T. japonicum , and T. chilonis had the least percentage of female progeny. The present study indicates that Trichogramma parasitoids (i) can distinguish fertilized vs. nonfertilized host eggs, and (ii) could use nonfertilized host eggs for successful offspring development (despite showing lower preference for such eggs) [corrected].
