Cytochrome P450 Genes CYP9A58 and CYP9A59 Contribute to Pyrethroid Tolerance in Spodoptera frugiperda.

Spodoptera frugiperda (J.E. Smith) is a notoriously destructive and invasive agricultural pest, causing substantial economic losses worldwide. Research has shown that cytochrome P450s play an important role in detoxifying insecticides. However, the precise molecular mechanism of P450-mediated detoxification of pyrethroids in S. frugiperda remains largely unknown. Enzyme activity assays demonstrated the involvement of P450 monooxygenases in pyrethroid detoxification in S. frugiperda. Subsequently, the results of induction experiments revealed that CYP9A58 and CYP9A59 were significantly upregulated by bifenthrin (up to 4.59- and 5.54-fold) and lambda-cyhalothrin (up to 4.17- and 3.28-fold). Stage- and tissue-specific expression analyses suggested that CYP9A59 exhibited predominant expression in sixth-instar larvae, and CYP9A58 was primarily expressed in the moth stage, with both P450 genes showing high transcript levels in the midgut. The functional role of P450s was confirmed by RNAi, where knockdown of either CYP9A58 or CYP9A59 significantly increased larval susceptibility to lambda-cyhalothrin, raising mortality by 45.71% and 57.68%, respectively. Furthermore, structural modeling demonstrated the capacity of both P450 enzymes-CYP9A58 and CYP9A59-to form stable complexes with pyrethroid insecticides. Collectively, these results confirm that CYP9A58 and CYP9A59 are key mediators of pyrethroid detoxification, conferring insecticide tolerance in S. frugiperda.