CYP6AB328-mediated spinetoram resistance via N-demethylation in Tuta absoluta: A potential resistance monitoring marker.

BACKGROUND

Tuta absoluta, a major pest of solanaceous crops, has rapidly evolved resistance to spinosyn insecticides, causing significant damage to global crops. Our previous study demonstrated that CYP6AB328 plays an important role in the development of spinetoram resistance. However, the direct metabolic role of this detoxification enzyme in spinetoram metabolism remains unclear.

RESULTS

In this study, we conducted a docking analysis between CYP6AB328 and spinetoram. Our docking analysis showed a good binding affinity between CYP6AB328 and spinetoram, with an energy of less than -6.0 kcal mol-1. Metabolomic analysis showed that recombinant CYP6AB328 exhibited substantial metabolic activity toward spinetoram-J (16.62%) and spinetoram-L (12.42%), which were metabolized into two products, N-desmethyl spinetoram J and N-desmethyl spinetoram L, respectively. We also found that laboratory-selected spinetoram-resistant strain of T. absoluta displayed 34-fold cross-resistance to spinosad, but little to no cross-resistance to imidacloprid (1.26-fold), chlorantraniliprole (1.12-fold), deltamethrin (1.76-fold) and avermectin (1.34-fold. Meanwhile, the expression level of CYP6AB328 was positively correlated with spinetoram resistance across four field populations of T. absoluta.

CONCLUSIONS

These findings provide valuable insights into the molecular mechanisms underlying detoxification of spinetoram and support the development of a candidate molecular marker for monitoring spinetoram resistance in the field populations, thereby contributing to improved pest management strategies. © 2026 Society of Chemical Industry.