4种农药对中华大蟾蜍蝌蚪和中国林蛙蝌蚪的急性毒性

Acute toxicity of four kinds of pesticides to the larvae of Bufo gargarizans and Rana chensinensis

为评价农药对两栖动物的毒性影响,以我国广布物种——中华大蟾蜍(Bufo gargarizans)和中国林蛙(Rana chensinensis)36期蝌蚪为试验材料,采用静态生物毒性试验方法测定了草甘膦、百草枯、马拉硫磷和溴氰菊酯对中华大蟾蜍蝌蚪和中国林蛙蝌蚪的急性毒性效应。结果表明,草甘膦、百草枯、马拉硫磷和溴氰菊酯对中华大蟾蜍蝌蚪的96 h-LC_(50)(半致死质量浓度)分别为205.52 mg/L、8.74 mg/L、1.81mg/L和69.14μg/L,对中国林蛙蝌蚪的96 h-LC_(50)分别为184.63 mg/L、6.49 mg/L、1.67 mg/L和65.17μg/L。依据LC_(50),所测试的4种农药对中华大蟾蜍蝌蚪和中国林蛙蝌蚪的急性毒性大小一致,从大到小均为溴氰菊酯、马拉硫磷、百草枯、草甘膦;但同一种农药对中华大蟾蜍蝌蚪和中国林蛙蝌蚪的急性毒性大小存在差异,表现为中国林蛙蝌蚪对上述4种农药的敏感性均高于中华大蟾蜍蝌蚪。依据《化学农药环境安全评价试验准则》,对中华大蟾蜍蝌蚪和中国林蛙蝌蚪而言,草甘膦的急性毒性级别为低毒,百草枯和马拉硫磷的急性毒性级别为中毒,溴氰菊酯的急性毒性级别为剧毒。

The present paper takes it as its aim to identify and determinate the acute toxicity of glyphosate, paraquat, malathion and dehamethrin for the two species of Chinese amphibian creatures, known as Bufo gargarizans and Rana chensinensis. The paper intends to take up the topic of the toxic effects of the following four common pesticides on the healthy living of the amphibians, which has not yet been well searched for. In proceeding with the research, we have managed to choose larvae of B. gargarizans and R. chensinensis at the Gosner stage 36 exposed to the four kinds of the most commonly used pesticides, namely, malathion, deltamethrin, glyphosate, and paraquat, which have been used in a 96 h acute toxicity testing series. The reason why we have chosen to conduct the testing series is that pesticides tend to have adverse effects on the survival, growth and development of the non- target organisms, including fish and amphibians, whereas rare had ever been studied on the analysis and estimation based on the acute mortality threat on the median lethal concentration （ LC50 ）. The results of the above testing and experimental series demonstrate that 96 h - LC50 of glyphosate, paraquat, malathion and dehamethrin for B. gargarizans tadpoles account for 205.52 rag/L, 8.74 mg/L, 1.81 mg/L and 69.14 μg/L, respectively, whereas those for R. chensinensis tadpoles should be equal to 184. 63 mg/L, 6. 49 mg/L, 1.67 mg/L and 65. 17μg/L, correspondingly. On the other hand, in terms of the toxic acuteness, no difference can be found either for B. gargarizans or for R. Chensinensis, that is, the order of toxic acuteness takes a descending order as is shown below： dehamethrin 〉 malathion 〉 paraquat 〉 glyphosate. In addition, we have also made comparison among the above mentioned four kinds of pesticide from the point of view of the sensitivity of B. gargarizans and R. chensinensis tadpoles in the paper. Judging by the indexes of 96 h - LC10, 96 h - LC50, and 96 h - LC90, it can be said that R. chensinensis tadpoles turn to be more sensitive to the said four kinds of pesticides than B. gargarizans tadpoles. Moreover, in accordance with Testing guidelines on environmental safety assessment for chemical pesticides, in terms of toxicity, glyphosate is low, paraquat and malathion are in the middle, and deltamethrin should be attributed to as extremely high for the larvae of B. gargarizans and R. chensinensis. In conclusion, it can be said that the given study can be expected to be qualified enough to provide valuable information and data for the toxicity study and safe use of pesticides that are supposed to have the potential to enter the aquarium system.