Combined detoxification mechanisms and target mutation fail to confer a high level of resistance to organophosphates in Cydia pomonella (L.) (Lepidoptera: Tortricidae)

Despite the frequent and widespread applications of organophosphates against Cydia pomonella this species has developed low levels of resistance to this chemical group. Investigations concerning the mechanisms involved in resistance are scarce, and usually consider only one of the potential mechanisms. With the aim of a better understanding the resistance mechanisms and their possible interaction, four of these mechanisms were investigated simultaneously in one sensitive (Sv) and two resistant strains (Raz and Rdfb) of this insect. Resistant strains displayed an increased mixed function oxidase activity, whereas carboxylesterase activity varied upon the substrate used. The three strains had similar β-naphtyl acetate activity, and the hydrolysis of α-naphthyl acetate and p-nitrophenyl valerate was higher in the Sv strain. The p-nitrophenyl acetate activity was highest in the resistant strains and was strongly inhibited by azinphos and DEF. The Raz strain has a modified acetylcholinesterase (AChE), which resulted in a 0.7-, 3.2- and 21.2-fold decrease in the susceptibility to chlorpyriphos-ethyl-oxon, azinphos-methyl-oxon, and paraoxon-methyl, respectively. These combined resistance mechanisms only conferred to Raz a 0.6-, 7.9- and 3.1-fold resistance to the related insecticides. Organophosphates resistance in C. pomonella results from a combination of mechanisms including modified affinities to carboxylesterase substrates, and increased metabolisation of the insecticide. The apparent antagonism between increased functionalisation and reduced sensitivity of the AChE target is discussed.     

检测有机磷残留的微生物传感器研究进展

有机磷杀虫剂广泛应用于世界农业中,因残留于水体与食物中,从而威胁到人类与动物健康。因此,需要实地快速、灵敏、有选择性地测定这些毒害神经的化合物。回顾了用于监测有机磷杀虫剂的生物传感器的进展,主要是应用基因重组技术构建了细胞表面表达有机磷水解酶的重组细胞作为构建微生物传感器的微生物,并总结了各类微生物传感器相关的优点与限制条件,以期为生物传感器研究提供思路与方法。