关键词: 淡色库蚊, 羧酸酯酶, 抗药性, 吡丙醚

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