中文摘要：

采用生物测定方法．对采自山西省晋源区和陕西省长安县的中华稻蝗种群对马拉硫磷的敏感性及其乙酰胆碱酯酶（ACHE）进行了研究。结果表明，长安种群比晋源种群对马拉硫磷的敏感性低4．79倍。动力学研究表明，晋源种群的动力学参数米氏常数（Km值）和最大反应速度（Vmax值）均比长安种群的高。体外抑制结果表明，两个种群中华稻蝗对所选用的3种有机磷杀虫剂的敏感性从高到低依次为：氧化毒死蜱〉对氧磷〉甲基内吸磷，且长安种群的双分子速率常数（k值）比晋源种群的低。体外抑制结果与生物测定的结果相一致，但动力学研究结果与生物测定存在差异。由此可见，两种群对马拉硫磷的敏感性差异的原因之一可能是乙酰胆碱酯酶的不敏感性，而与酶活性的升高没有明显相关性。

英文摘要：

Acetylcholinesterase （ACHE） was extracted from two field-collected populations of Oxya chinensis （Thunberg）（Jinyuan outskirts, Shanxi Province and Changan County, Shaanxi Province）. The results of bioassay showed that Changan （CA） population was 4.79-fold less susceptible, to malathion than Jinyuan （JY） population. Michaelis constant （Km） and maximum velocity （Vmax） values of JY population were higher than those of CA population. The inhibition study in vitro indicated that the AChE from both populations exhibited similar rank order in sensitivity to inhibition by three OPs, as determined by comparison of their bimolecular rate constants （ki, from the most to the least potent in-hibitors were chlorpyrifos-oxon〉paraoxon〉demeton-S-methyl for AChE from the two populations and that the ki values in CA population were lower than those in JY population. These results were consistent with the results in bioassay, but there existed differences between the results of kinetics study and the bioassay. AChE insensitivity to OP insecticides might contribute to the differences of insusceptibility to malathion of Oxya chinensis between the two populations whereas elevated AChE activities had no significant relationship with the differences of susceptibility.