常用农药对赤子爱胜蚓急性毒性和抗氧化酶系的影响

为评估农用化学品对蚯蚓的毒性,选择11种常用农药(吡虫啉、噻虫啉、阿维菌素、高效氯氰菊酯、吡蚜酮、噻嗪酮、毒死蜱、克百威、草甘膦、阿特拉津和百草枯)标准品和9种常用农药制剂作为受试物,采用人工土壤法研究其对赤子爱胜蚓(Eisenia fetida)的急性毒性效应,同时还测定了阿维菌素、吡虫啉和噻虫啉14 d暴露后对赤子爱胜蚓体内抗氧化酶(GST、CAT和T-SOD)活性和丙二醛(MDA)含量的影响。结果表明,11种常用农药毒性等级从高到低依次为吡虫啉噻虫啉克百威毒死蜱阿特拉津阿维菌素草甘膦吡蚜酮噻嗪酮高效氯氰菊酯和百草枯,其中吡虫啉、噻虫啉和克百威对赤子爱胜蚓为中毒,其余为低毒。制剂毒性试验结果表明,相对其活性成分,部分农药制剂对赤子爱胜蚓的急性毒性有所增强。此外,0.1 mg a.i.·kg~(-1)的噻虫啉14 d暴露能显著抑制蚯蚓体内CAT活性,而同样浓度下T-SOD活性显著性上升;0.25 mg a.i.·kg~(-1)的阿维菌素暴露14 d则能显著促进蚯蚓GST活性;阿维菌素、吡虫啉和噻虫啉分别在0.5、0.1、0.5 mg a.i.·kg~(-1)的暴露水平,可以诱导蚯蚓MDA含量出现显著性变化。研究表明农药的大量不合理施用会对土壤生物产生不利影响并因此干扰土壤正常的生态功能。

Influence of commonly used pesticides on acute toxicity to earthworm Eisenia fetida and alteration of antioxidant enzyme activities

In the present study, the acute toxicities of 11 commonly used pesticide technicals(imidacloprid, thiacloprid, avermectin, beta-cypermethrin, pymtrozine, buprofezin, chlorpyrifos, carbofuran glyphosate, atrazine and paraquat) and other 9 related pesticide formulations on Eisenia fetida were determined by using artificial soil test method. In addition, the several anti-oxidant enzymes(GST, CAT, and T-SOD) activities and MDA contents in Eisenia fetida were also determined after 14-d exposure to imidacloprid, thiacloprid and avermectin to evaluate the oxidative stress induced by pesticides in earthworm. The results show that the acute toxicity order of test pesticides technicals to Eisenia fetida was:imidacloprid > thiacloprid > carbofuran > chlorpyrifos > atrazine > avermectin > glyphosate > pymtrozine > buprofezin > beta-cypermethrin and paraquat. According to the Guidelines of Environmental Safety Evaluation for Chemical Pesticides, imidacloprid, thiacloprid and carbofuran were classified as medium toxic grade to Eisenia fetida under laboratory conditions by using artificial soil test method, while the other 8 pesticides were classified as low toxic grade to Eisenia fetida. The results of the acute toxicities of the pesticide formulations to Eisenia fetida showed that most of the formulations increased the toxicity to Eisenia fetida as compared to their corresponding active ingredients. Besides, the results of physiological and biochemical tests show that the CAT activity in Eisenia fetida was significantly inhibited by exposure to thiacloprid at 0.1 mg a.i.·kg^-1 soil, while the T-SOD activity in Eisenia fetida was significantly induced by exposure to thiacloprid at the same dose level. The GST activity was significantly induced in Eisenia fetida by exposure to avermectin at 0.25 mg a.i.·kg^-1 soil. The MDA content in Eisenia fetida was significantly changed by exposure to avermectin, imidacloprid and thiacloprid at 0.5, 0.1, and 0.5 mg a.i.·kg^-1, respectively. These results imply that the frequent application of pesticides might have adverse effects on the soil organisms and therefore may disturb the normal ecological function of soil.