Functional diversification of UDP-glycosyltransferase gene clusters for adaptation to host plants and pesticides in an invasive insect

The fall armyworm (FAW, Spodoptera frugiperda ) threatens global food security through exceptional host adaptability and rapid evolution of insecticide resistance. Here, our results suggest that the clustered UDP-glycosyltransferases ( UGTs ) of S. frugiperda play vital roles in phytochemical and insecticide detoxification. Through an innovative nanoparticle-enhanced RNAi screening system following CRISPR/Cas9 validation, we identify cluster functional diversification of UGTs in chemical stress adaptation. Bioassay analyses revealed that UGT cluster 1 (C1) mainly confers insecticide tolerance, whereas clusters 2 (C2) and 3 (C3) mediate adaptation to rice and corn, respectively. In vitro recombinant protein assays further reveal that C1 UGTs (UGT40M12 and UGT40R18) exhibit metabolic activity against insecticides such as emamectin B1a, whereas C2 UGTs (UGT33B25 and UGT33B26) specifically metabolize rice-derived flavonoids. Although not validated in this study, previous research has shown that UGT33F32 from C3 specifically metabolizes corn-derived phytochemicals, including DIMBOA. The differential substrate preferences of these UGTs toward both phytochemicals and insecticides underscore their pivotal roles in driving co-adaptation to host plants and chemical insecticides. This work not only elucidates the evolutionary significance of UGT cluster functional diversification as adaptation toolkits, but also provides novel insights for integrating host plant resistance and chemical control in pest management strategies.