CYP417A1 Contributes to Resistance to Both Nitenpyram and Buprofezin in a Field Population of Nilaparvata lugens

The brown planthopper (BPH), Nilaparvata lugens (Stål), is one of the most destructive insect pests of rice across Asia, and its management relies mainly on intensive use of chemical insecticides. Field-evolved resistance to multiple insecticides has emerged in N. lugens populations in many regions, yet the genes associated with reduced susceptibility to multiple compounds in field populations remain poorly characterised. We collected an N. lugens field population from Jiangmen (Guangdong, China) and obtained estimated resistance ratios of approximately 1013-fold for buprofezin and 159-fold for nitenpyram relative to published susceptible baselines. Comparative transcriptomic profiling of nymphs exposed to LC30 concentrations of buprofezin or nitenpyram identified 76 and 103 differentially expressed genes, respectively, with 28 shared between the two contrasts. CYP417A1 (LOC111047271) was the only cytochrome P450 significantly induced by both insecticides, and this transcriptional induction was corroborated by RT-qPCR. CYP417A1 belongs to the planthopper-associated CYP417 subfamily of the CYP4 clan. RNA interference-mediated silencing of CYP417A1 substantially increased 96 h mortality of nymphs subsequently exposed to either insecticide. Molecular docking predicted that both insecticides could occupy the same substrate-access pocket adjacent to the distal face of the heme, sharing predicted contacts with Phe118 and Phe224 while showing distinct anchoring patterns. Overall, the RNAi results support a contribution of CYP417A1 to reduced susceptibility to two insecticides with distinct modes of action, whereas basal expression differences between susceptible and field populations and direct metabolic activity remain to be established.