Dietary items of predacious aquatic bugs (Nepoidea: Heteroptera) in Japanese wetlands

Some species of predatory aquatic bugs (Nepoidea, including Belostomatidae and Nepidae) are designated as threatened-vulnerable species in the Red Data Book of Japan and are regarded as effective predators of freshwater snails and mosquito larvae. To reveal the feeding habits of Nepoidea, we investigated their dietary items in wetlands and obtained data from the published literature. Lethocerus deyrolli (Vuillefroy) preys mainly upon frogs, and the major diet of the nymphs is tadpoles. Laccotrephes japonensis (Scott) adults prey mainly upon tadpoles. Lethocerus deyrolli nymphs and L. japonensis adults compete against each other as same-guild members because they are sympatric in wetlands. Both nymphs and adults of Appasus japonicus (Vuillefroy) feed oil snails, and L. japonensis nymphs feed on aquatic insects, including mosquito larvae (39.3% of aquatic insects). These species are effective predators of medically important pests such as snails, and mosquito larvae.