关键词: 德国小蠊, 羧酸酯酶, 有机磷杀虫剂, 抗性机制

Abstract: Objective To study the role of carboxylesterase in the development of organophosphate resistance and the activity variance of carboxylesterase in different strains of German cockroach(Blattella germanica).Methods Relationship between carboxylesterase and organophosphate resistance in German cockroach was studied with bioassay,biochemical analysis and synergistic test.The cockroaches from the susceptible strain(SS) of laboratory and field strains of different areas in Beijing [Xuanwu(XW) district,Changping(CP) district,Shunyi(SY) district and Shijingshan(SJS) district] were used as test insects. Results The synergistic test showed that synergistic ratio of TPP to malathion and dichlorvos were 1.86 and 1.51 fold in susceptible strain,respectively.And in field strains(XW,CP,SY and SJS),they were 5.79,20.08,15.26 and 4.74 fold for malathion,respectively and 2.00,1.67,2.16 and 4.81 fold for dichlorvos,respectively.There was significant difference between the Michaelis-Menten constants(K_m) and the maximum velocity(V_max) of carboxylesterase from two strains of German cockroach.The K_m and V_max of caboxylesterase in susceptible strain were 0.1580 mmol/L and 58.4225 μmol/(mg pro·min),respectively.And in field strains(XW,CP,SY and SJS),the K_m and V_max of carboxylesterase were 0.1279,0.1071,0.1080,0.1095 mmol/L and 307.2550,338.5755,340.3300,212.4570 μmol/(mg pro·min),respectively.The inhibition medium concentration(I₅₀) of malathion and dichlorvos to caroxylesterase from SS strain were 17.64 mmol/L and 0.91 μmol/L,respectively.For field strains,the I₅₀ of malathion were 80.48,35.49,83.24 and 82.29 mmol/L,respectively,and that of dichlorvos were 15.35,7.89,11.52 and 8.60 μmol/L respectively.The inhibition of malathion and dichlorvos to caroxylesterase from SS strain(I₅₀ were) was much lower than from field strains strain(XW,CP,SY and SJS).Conclusion The enhancement of detoxification activity was one of resistance mechanism to organophosphate in German cockroach.