Prabhakaran S K, Kamble S T
Department of Entomology & Environmental Programs, University of Nebraska, Lincoln 68583-0816.
J Econ Entomol. 1993 Aug;86(4):1009-13. doi: 10.1093/jee/86.4.1009.
Strains of German cockroach, Blattella germanica (L.) were tested for resistance to three insecticides using the time-mortality response technique in comparison with known susceptible strains. Dursban-R and Macy strains indicated high levels of resistance to chlorpyrifos and moderate resistance to propoxur and cypermethrin. The hydrolytic activity of esterase enzymes was determined with a model substrate, p-nitrophenyl acetate. The specific activity of the enzymes increased with a corresponding increase in substrate concentration. Maximum activity was observed at 80 microM. The resistant strains had significantly higher activity than the susceptible strains. The enzyme activity also increased with an increase in pH. Highest esterase activity was observed at pH 8.0 for all the strains. The calculated Michaelis Menten constant (Km) values for the resistant strains were nearly two-fold higher than for the susceptible strains. Nondenaturing gel electrophoresis revealed differences in isozyme composition. In total, 10 esterase bands were detected, and these bands were characterized using different inhibitors and substrates.
采用时间-死亡率反应技术，将德国小蠊（Blattella germanica (L.)）品系与已知的敏感品系进行比较，测试其对三种杀虫剂的抗性。毒死蜱-R和梅西品系对毒死蜱表现出高抗性，对残杀威和氯氰菊酯表现出中等抗性。用对硝基苯乙酸作为模型底物测定酯酶的水解活性。酶的比活性随着底物浓度的相应增加而增加。在80微摩尔时观察到最大活性。抗性品系的活性明显高于敏感品系。酶活性也随着pH值的升高而增加。所有品系在pH 8.0时观察到最高酯酶活性。抗性品系的米氏常数（Km）计算值比敏感品系高出近两倍。非变性凝胶电泳揭示了同工酶组成的差异。总共检测到10条酯酶带，并使用不同的抑制剂和底物对这些条带进行了表征。
