Objective The cytochrome P450 gene from Ectropis grisescens Warren, CYP4G15, was cloned for bioinformatics and expression analysis in relation to the detoxification metabolism and resistance mechanism toward the pesticide indoxacarb of the most destructive defoliators at tea plantations in China.

Method The coding region of CYP4G15 was cloned using RT-PCR, the bioinformatics, gene sequence, and phylogenetic relationships with the P450 genes of other closely related species analyzed by software, and the gene expressions at developmental stages and after an indoxacarb induction of E. grisescens determined by RT-qPCR.

Result CYP4G15 was successfully cloned to show a full-length with an open reading frame of 1572 bp encoded with 523 amino acids. It had a predicted molecular weight of 59.85 kD and a theoretical isoelectric point at pH 8.85. The protein appeared to contain a conserved domain of the cytochrome P450 family closely related to Lepidoptera Noctuidae insects, such as Spodoptera frugiperda and Spodoptera exigua. CYP4G15 was highly expressed in the 3^rd and 4^th instar larvae, lowly in the eggs, and significantly higher in the male than in the female pupae and adults. The 3^rd instar larvae of E. grisescens treated by indoxacarb at LC₂₀ and LC₅₀ doses had its CYP4G15 reached the highest expressions that were 7.16-fold and 3.65-fold, respectively, of control 48h after the artificial induction.

Conclusion CYP4G15 appeared to play a significant role in the detoxification of E. grisescens against indoxacarb. This study unveiled a plausible new venue to advance the research on control of the debilitating pest in tea plantations.