Abstract:

Objective To preliminarily explore biochemical resistance mechanism by comparison the biochemical characteristic of carboxylesterase in pyriproxyfen-resistantand susceptible population of Culex pipiens pallens. Methods The activity of carboxylesteres (CarE) was determined by van Aspern(1962). Results The tendency of CarE activity change in hydrolyzing α-naphthyl acetate (α-NA) or β-naphthyl acetate (β-NA) depended on substrate concentration. The hydrolyzing activity was significantly higher in resistant population than in susceptible population with α-NA and β-NA as substrates within the certain concentration range. When substrate was β-NA, the Kinetic parameters (K_m) and V_max of CarE were 27.20×10-5 mol/L and 115.00×10-5 A/(mg·pro·min) in resistance population respectively, and that of CarE in susceptible population were 104.00×10^-5 mol/L and 207.00×10^-5 A/(mg·pro·min). Difference between them was significant (t_b=2.74, t_c=3.16). When substrate was α-NA, there was no significant difference between K_m (131.00×10^-5 mol/L) in resistance population and K_m (75.20×10^-5 mol/L) in susceptible population; but difference was significant between V_max of them. The CarE from resistant population was more sensitive to DDVP (dichlorvos) and propoxur than that from susceptible population. Conclusion Enhanced CarE activity maybe attributable to the resistance of Cx. pipiens pallens to pyriproxyfen.

Key words: Culex pipiens pallens, Carboxylesterase, Insecticide resistance, Pyriproxyfen

摘要：

目的 比较淡色库蚊抗吡丙醚种群和敏感种群羧酸酯酶生化特征的差异,初步探讨其生化抗性机制。方法 参照van Aspern(1962)的方法测定羧酸酯酶活性。结果 淡色库蚊抗性品系和敏感品系羧酸酯酶水解活性随底物浓度(α-乙酸萘酯或β-乙酸萘酯)的增加而升高;在一定浓度范围内,抗性品系对这两种底物的水解活性均高于敏感品系。β-乙酸萘酯为底物时,抗性品系羧酸酯酶的米氏常数(K_m)和最大反应速度(V_max)分别为27.20×10^-5 mol/L和115.00×10^-5 A/(mg·pro·min),敏感品系K_m和V_max分别为104.00×10^-5 mol/L和207.00×10^-5 A/(mg·pro·min),两者差异有统计学意义(t_b=2.740,t_c=3.160,P<0.05)。α-乙酸萘酯为底物时,抗性品系羧酸酯酶K_m为131.00×10^-5 mol/L,与敏感品系K_m(75.20×10^-5 mol/L)比较差异无统计学意义,而V_max则差异有统计学意义。胆碱酯酶抑制剂测定结果表明,抗性品系羧酸酯酶对敌敌畏和残杀威的敏感性高于敏感品系。结论 羧酸酯酶可能与淡色库蚊对吡丙醚的抗性有关。

关键词: 淡色库蚊, 羧酸酯酶, 抗药性, 吡丙醚