烯草酮、氯氰菊酯和2-4D丁酯对中华摇蚊（Chironomussinicus）幼虫的急性毒性试验

目的]评价农药对水生生物的毒理效应。方法]采用静水法研究烯草酮、氯氰菊酯和2．4D丁酯对中华摇蚊（Chironomussinicus）幼虫的急性毒性效应。分别设定不同浓度梯度进行急性暴露试验，于48h时测定摇蚊幼虫组织匀浆超氧化物歧化酶（SOD）的活性。结果]在氯氰菊酯和2-4D丁酯处理摇蚊幼虫后12h后，不同浓度间的存活率无显著差异，在48h时随着农药浓度的增加，存活率F降。烯草酮、氯氰菊酯和2-4D丁酯对中华摇蚊幼虫48h的LC。分别为1．842、0．150和1．999mg／L，氯氰菊酯对中华摇蚊幼虫的毒性最高．其次为烯草酮，2-4D丁酯毒性最低。烯草酮对中华摇蚊幼虫组织SOD含量有明显影响．表现出剂量-效应关系；2-4D丁酯对组织SOD含量有明碌影响．但未表现出剂量-效应关系：而氯氰菊酯对组织SOD含量则无明显影响。结论]该研究为水体污染监测和水环境中农药的残留提供理论依据。

Acute Toxicity of Clethodim,Cypermethrin and 2,4-D-butylate to the Larva of Chironomus sinicus

Objective] The aim of this study was to detect the acute toxicity of clethodim, cypermethrin and 2,4-D-butylate. Method] Chironomus sinicus larvae were exposed to different concentrations of clethodim, cypermethrin and 2,4-D-butylate. Survival rate, lethal concentration 50 （LC50） and superoxide dismutase （SOD） activity in the homogenate of the larvae were monitored to detect the toxicity of the pesti- cides. Result] The survival rates of C. sinicus larvae exposed to cypermethrin and 2,4-D-butylate for 12 h were almost unchanged at different concentrations, but de- creased with concentration increasing 48 h later. For each pesticide, the differences in survival rates of C. sinicus larvae at 48 h were significant. The 48 h LC50 of clethodim, cypermethrin and 2,4-D-butylate to C. sinicus larvae were 1.842, 0.150 and 1.999 mg/L, respectively. The acute toxicity of cypermethrin was the highest a- mong the three pesticides and that of 2,4-D-butylate was the lowest. Clethodim sig- nificantly reduced the SOD content in a dose-dependent manner. 2,4-D-butylate also reduced SOD content in C. sinicus larvae, but the reduction was not significantly re- lated to its dosage. However, cypermethrin showed no significant effect on SOD ac- tivity in C. sinicus larvae.