The Establishment of a Highly Sensitive Insecticidal Activity Detection System Using Silkworm First Instar Larvae Enables an Efficient Search Method for Insecticide Seed Compounds

Moth pests are the most commonly reported arthropod groups to develop resistance to insecticides and cause serious agricultural damage worldwide. Therefore, there is a need to develop new insecticides for crop protection, but it is extremely difficult to discover insecticide seed compounds using lepidopteran pests as test organisms because of their low insecticide sensitivity. In this study, we constructed a highly sensitive insecticidal activity detection system using silkworm first instar larvae to obtain promising insecticidal compounds against moth pests. As the result of screening 724 substances in the O̅mura Natural Compound (O̅NC) library via this new silkworm system, borrelidin, a natural product derived from actinomycetes, was identified as an insecticidal compound for silkworms. Moreover, borrelidin also showed insecticidal activity on three species of moth pests. Here, we propose an efficient search method for insecticide seed compounds against moth pests, together with some verification results.