<scp> MicroRNA <i>Lse‐novel_mir63</i> </scp> regulates metamorphosis and fumigant tolerance by targeting <scp> <i>CYP4G249</i> </scp> in <scp> <i>Lasioderma serricorne</i> </scp>

BACKGROUND: Genes in the CYP4G subfamily are essential for the final steps of cuticular hydrocarbon (CHC) biosynthesis, which influences insect metamorphic development, desiccation tolerance, and insecticide penetration. However, the functional roles and regulatory mechanisms of CYP4G genes in Lasioderma serricorne, a major stored-product pest, remain poorly understood. RESULTS: In this study, we identified the CYP4G249 gene in L. serricorne, exhibiting conserved CYP4G structural features. RNA interference (RNAi)-mediated knockdown of CYP4G249 significantly reduced CHC content, impaired larval molting, decreased body weight, and increased desiccation susceptibility. Histological analysis revealed thinning of the newly formed epidermis, while scanning electron microscopy showed cuticular wrinkling and spiracle collapse in dsCYP4G249-treated larvae. Silencing CYP4G249 also enhanced larval mortality following exposure to ethyl formate and methyl isothiocyanate. At the post-transcriptional level, Lse-novel_mir63 was shown to target the coding region of CYP4G249, and administration of Lse-novel_mir63 mimics suppressed CYP4G249 expression, recapitulating the RNAi phenotypes. Overexpression of Lse-novel_mir63 further increased larval susceptibility to fumigants. CONCLUSIONS: These results demonstrate that Lse-novel_mir63 regulates CYP4G249 expression, controlling CHC biosynthesis, larval metamorphosis, and fumigant tolerance in L. serricorne. The CYP4G249-Lse-novel_mir63 axis represents a promising molecular target for RNAi- or miRNA-based pest management strategies, potentially enhancing fumigant efficacy while disrupting insect development. © 2026 Society of Chemical Industry.