Characterization and Functional Analysis of Three Cytochrome P450 Monooxygenases in <i>Lasioderma serricorne</i> : Assessing Their Contribution to Lambda‐Cyhalothrin Susceptibility Through RNA Interference

In insects, cytochrome P450 monooxygenases (CYPs) play a pivotal role in the detoxification of various insecticides. The cigarette beetle, Lasioderma serricorne, is an economically important pest of stored products, for which pyrethroid insecticides are increasingly used. Nevertheless, the responses and functions of CYPs in L. serricorne under pyrethroid exposure remain poorly understood. In this study, three full-length CYP cDNAs were identified from L. serricorne and designated as CYP6BK29, CYP6SY1, and CYP6TE1. Phylogenetic analysis revealed that these CYPs belong to the CYP3 clan and the CYP6 family. Reverse transcription-quantitative PCR showed that CYP6BK29 and CYP6SY1 were predominantly expressed in the larval midgut, whereas CYP6TE1 transcripts were enriched in the fat body. The expression of CYP6BK29 peaked in the third- and fourth-instar larvae, while CYP6SY1 was specifically highest in the fourth-instar. In contrast, CYP6TE1 showed the highest mRNA levels in adults. Exposure to a sublethal dose (LD₃₀) of lambda-cyhalothrin (LCT) significantly upregulated the mRNA levels of CYP6BK29 and CYP6TE1, but not that of CYP6SY1. RNAi-mediated knockdown of CYP6BK29 significantly increased the susceptibility of larvae to LCT. In contrast, silencing CYP6SY1 or CYP6TE1 had no significant effect on larval survival under LCT exposure. These results provide evidence that CYP6BK29 contributes to LCT detoxification in L. serricorne, highlighting its potential as a molecular target for novel pest management strategies.