Multimodal Insecticidal Activity of α-Humulene Against Chilo suppressalis via Endocrine Disruption and Transcriptional Suppression of Cuticular Proteins.

Striped rice stem borer (Chilo suppressalis, SSB) poses a substantial threat to global rice production, leading to considerable economic loss. In this study, we explored the insecticidal mechanism of α-humulene, a sesquiterpene derived from Humulus lupulus, against SSB larvae. Bioassays indicated that α-humulene markedly elevated larval mortality rates and extended developmental periods. Transcriptomic analysis revealed the upregulation of genes involved in juvenile hormone (JH) biosynthesis and the downregulation of cuticle protein genes. Molecular docking experiments demonstrated that α-humulene could form putative binding interactions with both cuticular proteins and key enzymes in the JH biosynthesis pathway, suggesting a potential interaction that may influence the structural stability of the cuticle and hormonal balance. Furthermore, JH and ecdysone titer assays confirmed hormonal imbalance in treated larvae. This study identified α-humulene as a novel multimodal insecticidal compound targeting two critical systems, namely endocrine disruption via dysregulated JH biosynthesis, and structural integrity impairment through cuticle protein suppression, presenting a sustainable approach for the eco-friendly management of rice pests.