Functional characterization of PxUGT33W1 with abamectin response and reproduction in Plutella xylostella.

UDP-glycosyltransferases (UGTs) are key Phase II detoxification enzymes involved in insect xenobiotic metabolism; however, the functional contribution of individual UGT genes to abamectin response in Plutella xylostella remains poorly understood. In this study, we characterized a candidate gene, PxUGT33W1, using a combination of molecular, cellular, and genetic approaches. PxUGT33W1 exhibited broad expression across developmental stages and tissues, with elevated transcript levels in the midgut, epidermis, and reproductive organs. Its expression was significantly induced following abamectin exposure in a time-dependent manner, suggesting a stress-responsive pattern. Heterologous expression of PxUGT33W1 in Sf9 cells was associated with increased cellular survival under abamectin treatment, although whether this effect reflects direct enzymatic activity remains to be determined. CRISPR/Cas9-mediated knockout of PxUGT33W1 was associated with a 3.1-fold increase in larval susceptibility to abamectin, accompanied by a significant reduction in overall UGT activity toward α-naphthol. Furthermore, the knockout strain exhibited reduced fecundity, along with altered expression of vitellogenin (Vg), vitellogenin receptor (VgR), and juvenile hormone signaling-related genes. Collectively, these findings suggest that PxUGT33W1 may contribute to variation in abamectin susceptibility and reproductive performance in P. xylostella. However, direct biochemical evidence for abamectin metabolism by PxUGT33W1, such as its glycosylation, and the mechanistic basis of the observed phenotypes remain to be established.