Esterase activity and organophosphate resistance in Culex pipiens pallens (Diptera: Culicidae) populations in Zhejiang

Abstract

This research measured the lethal concentrations of dipterex to larval populations of Culex pipiens pallens L. in Zhejiang and determined the esterase activity level in each female population. The LC50 of dipterex for each larval population was 0.35 ppm for Ningbo, 0.46 ppm for Hangzhou, 0.47 ppm for Zhoushan, 0.66 ppm for Wenzhou, 0.71 ppm for Jiaxing, 0.75 ppm for Jinhua, and 1.43 ppm for Taizhou. The average integral value, the index of esterase activity for each female population, was 5,780.7 for Ningbo, 6,425.9 for Hangzhou, 7,045.9 for Zhoushan, 7,259.9 for Jiaxing, 8,283.2 for Jinhua, 9,046.3 for Wenzhou, and 12,907.9 for Taizhou, which were higher than those in the early 1990s. The index of esterase activity provided the following levels of resistance: Ningbo was classified as a region of low OP resistance; Hangzhou, Zhoushan, and Jiaxing were regions of middle OP resistance; Jinhua and Wenzhou were regions of middle to high resistance; and Taizhou as a region of high resistance.