Polymorphism and Distribution of Ace Gene Involved in the Resistance of Musca Domestica to Organophosphates in Guizhou Province of China

Acetylcholinesterase is the primary target of organophosphates (OPs) and carbamates in insects. As gene mutation has been verified as an important mechanism of insecticide resistance in insects, in this study, we investigated the status of OPs resistance and the polymorphism of ac e gene (that encodes acetylcholinesterase) in housefly ( Musca domestica L ) field populations in Guizhou Province, China. Bioassays showed that the houseflies had 142.16–303.54-fold resistance to dichlorvos (DDVP) and 122.13–363.98-fold resistance to temephos. Molecular analysis revealed resistance-causing mutations of a ce gene at loci of 260, 342 and 407 in the housefly populations, with a total frequency of 55%, 100% and 94%, respectively. In addition, 11 combinations of a ce mutation were observed across the detected populations. The most frequently detected combination was L/V+A/V+Y, followed by L+A+Y and L/V+A+Y. No significant relationship was found between single mutation/combination mutations and DDVP resistance. These results indicate that the OPs resistance is prevalent among the housefly populations in Guizhou Province, with a similar pattern of allele mutation of ace across China. The target resistance can not fully account for the resistance of houseflies to OPs in Guizhou.