Aedes albopictus CYP6Z8 metabolizes multiple AChE-inhibiting insecticides

The Asian tiger mosquito Aedes albopictus transmits several arboviruses, including chikungunya, Zika, and dengue, posing serious public health threats. The excessive use of insecticides has led to increasing resistance to commonly applied insecticides in this species. We previously observed that enhanced expression of a CYP6Z8 homolog (AalbCYP6Z8) was associated with insecticide resistance in two field populations of Ae. albopictus; however, its capacity in insecticide metabolism had not been biochemically characterized. In this study, to explore the potential role of AalbCYP6Z8 in insecticide metabolism, a fully functional enzyme system was reconstituted in vitro by using Escherichia coli-produced recombinant AalbCYP6Z8 and NADPH-dependent cytochrome P450 reductase along with cytochrome b5. Our metabolism assays showed that CYP6Z8 was capable of metabolizing organophosphates (temephos and malathion) and carbamates (propoxur and bendiocarb), but not pyrethroids (deltamethrin and permethrin). Mass spectrometry analyses tentatively identified the structures of specific metabolites, revealing that AalbCYP6Z8 transforms organophosphates through oxidative desulfurization and carbamates through dealkylation and hydroxylation. This work demonstrates that AalbCYP6Z8 is a versatile metabolizer of acetylcholinesterase-inhibiting insecticides.