Bo Liu, Si-Yi Chen, Zhi-Hong Li, Shao-Kun Guo
Bactrocera dorsalis (Hendel) is a globally significant quarantine pest, and broflanilide represents a new insecticide with potential for its management. However, the molecular responses of B. dorsalis to broflanilide, particularly the involvement of cytochrome P450 genes, remain poorly understood. To address this gap, we compared the midgut and fat body transcriptomes of adults that survived 24 h of exposure to the median lethal concentration (LC50) of broflanilide with those of corresponding controls. Candidate P450 genes were further examined by quantitative real-time PCR (qRT-PCR), RNA interference (RNAi), and molecular docking. RNA-seq identified strong upregulation of CYP6G8 (log2FC = 11.84 and 6.32) and CYP6GX5 (log2FC = 6.48 and 7.83) in the broflanilide-exposed surviving group. qRT-PCR showed that CYP6G8 was significantly upregulated in both tissues, whereas CYP6GX5 was significantly upregulated in the fat body but showed a nonsignificant upward trend in the midgut. Silencing CYP6G8 increased mortality from 43.21% to 64.14%, and CYP6GX5 silencing increased mortality from 31.11% to 87.07% following broflanilide exposure. Docking analyses predicted possible interactions between both proteins and desmethyl-broflanilide (DM-8007), the active metabolite of broflanilide. These results identify CYP6G8 and CYP6GX5 as candidate P450 genes associated with broflanilide tolerance under the tested conditions, although their direct biochemical roles remain to be determined.