Multiple evolutionary events in host plant adaptation in Lepidoptera

The evolution of insect host adaptation is a key component of insect-plant coevolution, a complex process often shaped by multiple evolutionary events. In this study, we identified two UDP-glycosyltransferase (UGT) genes,SfruUGT33T10andSfruUGT33F32, in the fall armywormSpodoptera frugiperda, which play critical roles in the tolerance of benzoxazinoids (BXs), secondary metabolites in maize. These two detoxification enzymes exhibited distinct glycosylation patterns for BXs and varying detoxification efficiencies, reflecting independent evolutionary trajectories. Phylogenetic analyses revealed thatSfruUGT33T10originated independently within Noctuidae, whileSfruUGT33F32resulted from tandem duplication within the UGT33F gene family and may have undergone neofunctionalization within theSpodopteragenus. Our findings provide evidence that the evolution of these two UGT paralogs contributed to the variation in the tolerance to maize BXs among different Lepidopteran species. This research underscores the significance of multiple independent evolutionary routes in host plant adaptation and offer new insights into the complex evolutionary processes underlying insect-plant interactions.