氯虫苯甲酰胺对我国土壤跳虫种群的生态毒理效应和分子机制研究

Toxicity of pesticides on soil fauna and environment has been highlighted worldwide in recent years. Chlorantraniliprole was introduced into China from 2008 as a novel pesticide and exhibits good efficacy in controlling pests on crops. It has negligible acute toxicity on nontarget animals, however, research should be taken to study how this pesticide affect them sublethally. Collembola and other soil fauna play an important role as decomposers of leaf litter and soil organic matter, and may give an earlier indication of ecosystym disturbance than predaceous soil animals. Collembola are also known as ideal test animals for ecotoxicological research. They have been used to study the effects of various environmental contaminants such as heavy metals and pesticides on animals. In this study, we try to study effects of chlorantraniliprole on some collembolan species (Folsomia candida and Sinella curviseta), including acute toxicity test, reproduction and sublethal toxicity test. The protocol of the standard ISO (1999) laboratory test will be followed. In addition, we will try to find changes in behavior, physiology and biochemistry on collembola. Some biomarkers, such as metabolic enzymes, defensive proteins and DNA damage will be detected, and molecular mechanism of these differences will be analyzed and discussed. Hopefully, several useful biomarkers could be found to indicate chronic toxicity of Chlorantraniliprole on soil animals and environment, which would be useful for soil ecotoxicology and environmental risk assessment.

新型农药氯虫苯甲酰胺在我国投入使用时间较短，效果好且不直接杀伤非靶标动物。然而它对于土壤中非靶标动物的慢性毒理效应需要进一步研究。跳虫是国际上土壤生态毒理研究广泛应用的指示生物。本课题拟在室内进行白符跳和曲毛裸长角跳的农药毒理学试验，采用自然土壤法模拟农田施药环境，以这两种跳虫为对象，研究氯虫苯甲酰胺对跳虫种群以及土壤环境的毒性效应。采用室内急性处理和长期慢性暴露处理相结合的设计，研究农药对其行为、生存率、繁殖率等生物学指标的毒性效应；进一步测定农药长期低剂量暴露对跳虫重要生物标志物的影响；分析氯虫苯甲酰胺对跳虫DNA损伤和几种防御性蛋白基因表达水平的分子反应机制。本研究将为我国农田土壤环境评估提供指示生物与生物标志物参考，也为氯虫苯甲酰胺的土壤生态环境毒理学提供研究资料。

氯虫苯甲酰胺（CAP）是广泛使用的新型杀虫剂。主要防治鳞翅目害虫等靶标害虫，对非靶标动物毒性较低。近年来有研究表明，CAP对于非靶标节肢动物如白符跳存在较大的繁殖毒性，本项目为此进行以下研究：.分别以白符跳和奇裸长角跳为对象，研究人工土壤中CAP对两种跳虫的繁殖毒性，得出的繁殖率半抑制浓度分别为：0.533 mg/kg dw和>1000 mg/kg dw，CAP对前者的毒性等级为高毒，对后者为低毒。.在亚致死浓度暴露下研究CAP对两种跳虫的抗氧化防御系统的影响，结果显示CAP能够不同程度影响影响两种跳虫的生理生化指标，尤其是过氧化氢酶、谷胱甘肽还原酶、谷胱甘肽转移酶，其次是总谷胱甘肽和脂质过氧化物，对金属硫蛋白无显著影响。.以湖南红壤、江苏黄壤、北京潮土、吉林黑土和OECD人工土壤为测试介质，进行典型土壤中CAP对白符跳的繁殖试验，得出5种土壤中白符跳的繁殖率半抑制浓度分别为0.0499、0.970、0.183、0.673和0.533 mg/kg dw，CAP对白符跳的毒性处在剧毒和高毒等级。5种土壤中白符跳体长增长10%抑制浓度分别为0.0132、0.0121、0.0175、0.1214和0.0290 mg/kg dw。.CAP慢性暴露后，对两种跳虫的相关生理生化指标在mRNA水平的表达的影响：白符跳体内谷胱甘肽转移酶基因表达量和GST活性、过氧化氢酶基因和CAT活性保持了比较对应的关系，而细胞色素P450 I表达量变化最为敏感。.对CAP进行土壤动物跳虫的风险评估：CAP在人工土壤、湖南红壤、北京潮土中对于白符跳的风险系数分别为：1.13、12.0、3.28，风险不可接受；而在江苏黄土和吉林黑土中的风险系数分别为0.619和0.892，风险均可接受。.本研究的科学意义在于：首次采用中国广布种奇裸长角跳进行CAP的生态毒理学研究；从种群、个体、细胞等多角度研究农药对跳虫的生态毒理学效应，筛选出合适的指示生物和灵敏、可靠的生物标志物，从分子层面寻找生理生化指标变化背后的毒性机制；为CAP的环境监测和建立科学的评价方法体系作参考；获得的数据可用于评价农药对土壤跳虫的风险；针对不同典型土壤的性质特点，提出需考虑污染物在不同土壤中生物有效性与毒性的差异。