Eurycomanone (EN) Activates Transcription Factor FoxO by Inhibiting the Insulin Signaling Pathway to Suppress the Development of Spodoptera frugiperda .

The insulin-like signaling (IIS) pathway is essential for insect growth and development. In this study, we showed that eurycomanone (EN) is an active compound with growth inhibitory activity against Spodoptera frugiperda larvae. Experiments in cells and RNA-seq analysis in the midgut showed that EN targeted the IIS pathway in S. frugiperda to activate the transcription factor SfFoxO ( S. frugiperda forkhead boxO) to regulate mRNA levels associated with nutrient catabolism. Additionally, mass spectrometry imaging revealed that EN was distributed in the larval gut and enriched in the inner membrane of the gut. Immunofluorescence, western blotting, and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) results showed that EN induced program cell death (PCD) in the larvae midgut. Thus, EN targeted the insulin receptor to inhibit the IIS signaling pathway, exerting inhibitory activity on the growth and development of S. frugiperda larvae. Our results suggest that EN has great potential as a botanical pesticide, and the IIS signaling pathway may be an effective target for botanical pesticides.