Recently, it has been reported that plants produce variety of phytochemicals against insect pests as a part of their defencemechanism. In this study, to identify novel compounds that disrupt juvenile hormone (JH) receptor complex, plant essentialoil compounds were tested using in vitro yeast two-hybrid system transformed with the Aedes aegypti JH receptor complex.Among the plant essential oil compounds, farnesol interfered with pyriproxyfen-mediated binding of A. aegypti Met-FISC.In contrast, farnesyl acetate induced the binding of A. aegypti Met-FISC. Also, both compounds caused retardation ofovarian development and change of transcription level in female A. albopictus. These results could provide insights onthe plant-insect coevolution and may be useful for the development of insect specific and safe pesticides.

Insect growth regulators (IGRs) are insecticides that disrupt the normal development of target insects by inducing symptoms such as premature molting or supernumerary larval stages. Juvenile hormone (JH)-based IGRs are of particular interest because they simulate or interfere with the formation of juvenile hormone receptor complex. Insect larvae generally have been poorly susceptible to JH agonists (JHAs) because endogenous JH titer is already high in the larval stage. In contrast, JH antagonists (JHANs) might be more effective for control of target pests in larval stages through interference in the status quo action of JHs. In this study, we tested 2,354 chemical compounds using the yeast-two hybrid system to identify JHANs. Among them, K265674 sample was selected and its insecticidal activity was evaluated against Aedes albopictus larvae. These results may be useful for development of novel IGR insecticide.

Entomopathogenic fungi have been widely studied for their potential as the effective biological control agents. They produce variety of secondary metabolites with insecticidal activities, and it is reasonable to assume that entomopathogenic fungi might produce secondary metabolites modulating juvenile hormone for their survival against defense mechanisms of host insect. In this study, Beauveria spp. and Lecanicillium spp. strains cultured on unpolished rice medium were extracted with acetone. Both extracts showed juvenile hormone antagonist (JHAN) activities in the yeast-two hybrid β-galactosidase assay. In addition, they showed high insecticidal activities against Aedes albopictus, Plutella xylostella, and Ostrinia furnacalis. These results suggested that secondary metabolites of entomopathogenic fungi could be useful for development of novel IGR insecticides.

Insect growth regulators (IGRs) are insecticides that disrupt the normal development of target insects by inducing symptoms such as premature molting or supernumerary larval stages. IGRs are categorized into three types based on their mode of action. One of the them is classified as juvenile hormone agonists (JHAs). In recent studies, we identified juvenile hormone antagonists (JHANs) from plant extracts. In order to identify a novel juvenile hormone agonists and antagonists, we tested 2,354 chemical compounds using the yeast-two hybrid system. Among them, 2 JHAs and 4 JHANs were selected and their insecticidal activities were evaluated against Aedes albopictus larvae. These results may be useful for development of novel IGR insecticides.