Cytochrome <scp>P450</scp> ‐mediated regulation of pheromone biosynthesis and adult emergence in <i>Monochamus saltuarius</i> ( <scp>Coleoptera, Cerambycidae</scp> ), with implications for pest management

BACKGROUND: Monochamus saltuarius is a key vector of pine wood nematode in northeastern China, and its development and pheromone biosynthesis directly influence pine wilt disease spread. Cytochrome P450 monooxygenases (P450s) are crucial for insect lipid metabolism, hormonal regulation, and pheromone biosynthesis, but their functions in M. saltuarius remain largely unknown, hindering targeted pest management. RESULTS: Based on transcriptomic of M. saltuarius, 61 candidate P450 genes were identified. Bioinformatic analysis further narrowed these to 13 candidate genes potentially involved in pheromone biosynthesis, which were subsequently subjected to phylogenetic analysis and spatiotemporal expression profiling. RNA interference (RNAi) was then employed to functionally characterize two P450s in females (CYP6HD1 and CYP4G300) and three in males (CYP6HD1, CYP6BJ72, and CYP6BJ48). The results demonstrated that CYP4G300 in females and CYP6HD1 in males had dual effects in pheromone biosynthesis and adult emergence. In contrast, CYP6BJ48 functioned specifically exclusively in male pheromone biosynthesis, highlighting functional divergence among P450s. Notably, CYP6HD1 exhibited sex-specific regulatory patterns, reflecting differences in pheromone composition and physiological demands between sexes. Moreover, RNAi of selected P450s altered 20E levels, supporting the view that these genes may influence pheromone biosynthesis and emergence through hormone-associated and lipid metabolic pathways, including THF-diol-related processes. CONCLUSION: Our findings demonstrate that P450s in M. saltuarius coordinately regulate pheromone biosynthesis and adult development through lipid metabolic and hormonal pathways. These results provide mechanistic insights into insect chemical communication and identify P450s as promising molecular targets for the development of novel, environmentally friendly pest management strategies against this important forest pest. © 2026 Society of Chemical Industry.