Abstract: The toxicity of four kinds of insecticides (7504, trichlorphon, sevin, deltamethrin) to Daphnia magna can be determined with the method of biological toxicity and the method of biochemical toxicity. Of four insecticides, deltamethrin has the most efficient toxicity to Daphnia magna, its 24h LC₅₀ being 0.385 μg/L. Next is trichlorphon, 24h LC₅₀ being 0.74 μg/L. Third is sevin, 24h LC₅₀ being 18.6 μg/L.The last is 7504 and its 24h LC₅₀ being 303.7 μg/L. According to the results of the method of biological toxicity, we culture Daphnia magna in culture solutions added with insecticides (LC₀ and LC₅₀) separately and determine important enzyme's activity and K_m (AChE, Carboxylesteraes and so on). The results show: different insecticides can affect the enzymes differently, and the method of biochemical toxicity is more sensitive and more accurate than the method of biological toxicity.

Key words: Daphnia magna, Enzyme's activity, Insecticide

摘要： 利用生物毒性测试法与生化毒理测试法，分别探讨了4种杀虫药剂(7504、敌百虫、西维因、溴氰菊酯)对大型蚤幼蚤的毒性。其中溴氰菊酯的毒性最大，24h LC₅₀为0.385μg/L；敌百虫次之，2.748μg/L；西维因为18.6μg/L；7504为303.7μg/L。在生物毒性测试的基础上选择不同浓度的杀虫药剂对大型蚤幼蚤进行培养，测其重要的酶系(乙酰胆碱酯酶、羧酸酯酶等)活性的变化。结果表明，不同的杀虫药剂对不同酶的酶活性有着不同程度的影响，并证明了生化毒理测试法较灵敏、精确。

关键词: 大型蚤, 杀虫药剂, 酶活性