A cytochrome P450 monooxygenase (CYP337B5) plays a key role in regulating juvenile hormone biosynthesis and degrading chlorantraniliprole in Spodoptera frugiperda (Lepidoptera: Noctuidae)

Cytochrome P450 monooxygenase (P450) has been shown to be involved in the detoxification metabolism of exogenous drugs or regulates the endogenous synthesis of juvenile hormone III (JH III). However, it is not yet known whether a particular P450 gene involved in the metabolism also affects the synthesis of juvenile hormones. Fall armyworm (FAW, Spodoptera frugiperda) showed a significant increase in juvenile hormone I (JH I) and juvenile hormone II (JH II) under chlorantraniliprole stress, and 11 chlorantraniliprole resistance-related P450 genes were significantly up-regulated. Among them, CYP337B5 was not only overexpressed in the midgut and head of FAW larvae, but also significantly increased in the female and male adult stages with high JH I and JH II titers. Injecting double-stranded RNA significantly reduced the metabolism rate of chlorantraniliprole in FAW and inhibited the production of juvenile hormones. Additionally, the degradation rates of chlorantraniliprole were significantly increased along with the production of various metabolites when incubated in vitro using recombinant CYP337B5; and JH I and JH II were also increased to some extent by 1.2 and 0.5 times. The results show that CYP337B5 is efficiently involved in the metabolism of chlorantraniliprole and specifically involved in the synthesis of JH I and JH II. We show that some P450s may have dual functions of endogenous hormone synthesis and exogenous substance metabolism in insects, which may be the root cause of the cost of drug resistance in insects.