三唑磷和氯氟氰菊酯对蚯蚓的联合毒性效应

近年来农药复配使用成为普遍现象,它对生态的危害是否有别于农药单独使用?采用OECD人工土壤法,通过急性毒性、回避行为及抗氧化酶(CAT、POD、SOD)活性3个生态响应水平,研究三唑磷和氯氟氰菊酯对蚯蚓的联合毒性效应。结果表明:三唑磷对蚯蚓7 d和14 d的半数致死浓度(LC50)分别为331.1 mg·kg~(-1)和122.0 mg·kg~(-1);氯氟氰菊酯对蚯蚓7 d LC50和14 d LC50分别为897.9 mg·kg~(-1)和656.7 mg·kg~(-1)。2种农药按毒性比1:1复配,表现为协同作用。三唑磷和氯氟氰菊酯对蚯蚓48 h的半数回避浓度(AC50)分别是41.6 mg·kg~(-1)和6.0 mg·kg~(-1),两者亦表现为协同作用。经2种农药单独处理,蚯蚓体内CAT活性呈现轻微上升后下降,而POD和SOD活性无明显变化;复配导致POD活力显著上升,而CAT和SOD活力则显著下降。研究表明:三唑磷和氯氟氰菊酯复配呈现协同作用,增强彼此对蚯蚓的毒性作用,增大土壤生态危害风险;联合效应的产生与其阻断神经传导这一共同靶标有关。

The Single and Joint Toxicity of Tiazophos and Cyhalothrin to Earthworm

The usage of pesticide mixture has been a common method for agriculture which may have many differ￣ences with the single use of pesticide. The joint toxicity effect of tiazophos and cyhalothrin to earthworm were studied using OECD artificial soil method. Acute toxicity, adviodance behavior and antioxidant enzyme activities (CAT, POD, SOD ) were observed. The result indicated that 7 d￣LC50 and 14 d￣LC50 of tiazophos are 331.1 mg?kg￣1 and 122.0 mg?kg￣1 in acute toxicity test;7 d￣LC50 and 14 d￣LC50 of cyhalothrin are 897.9 mg?kg￣1 and 656.7 mg?kg￣1 . The mixture with the ratio of 1:1 of toxic unit showed synergistic effect. The medium concentration for a￣voidance behavior (AC50 ) of tiazophos is 41.6 mg?kg￣1 and of cyhalothrin is 6.0 mg?kg￣1 in adviodance behavior experiment. The mixture showed synergistic effect. Enzyme activities test indicated that CAT activity rose after de￣creased when Eisenia foetida was exposed to two pesticide singly. The POD activity increased in the joint expo￣sure. The CAT and SOD activities decreased in the joint exposure. It is concluded that joint exposure can strengthen toxicity to E. foetida. Joint toxicity effect of tiazophos and cyhalothrin is related to blocking the nerve transduction.