Eco-toxicity Evaluation Of Pesticides Carbaryl To Soil Fauna And Flora

Carbamate pesticides represented by carbaryl became the second main force after organophosphorus pesticides when they entered markets in the 1950s. Carbaryl is widely used in fruit trees, vegetables, crops, medicinal herbs, teas and so on. The toxic effects of carbaryl are exposed day by day, interfering endocrine system, injuring reproductive system and influencing the human health. Because of the widespread use of the carbaryl in agricultural ecosystem, and the possibility of field soil contamination, therefore, the eco-toxicity evaluation of carbaryl to soil fauna and flora has great realistic significance, which could provide evidences for food security assurance, reasonable application of pesticides and rebuilding a correct understanding of pesticide.There were a few eco-toxicity evaluations of carbaryl to some animals at present; however, the study on eco-toxicity of carbaryl to plants was scarce. The present evaluation level was also limited to one or other direction of evaluation level, especially lack of eco-toxicity evaluation at the molecular level. The purpose of this paper is to evaluate the inhibition effects of carbaryl on seed roots elongation of several common crops at the physiological level, evaluate the acute toxicity of carbaryl to earthworm (Eisenia foetida) at the individual level, evaluate the damage of the earthworm body cell DNA at the molecular level with the method of Comet assay (Single-cell gel electrophoresis,SCGE). The main conclusions are as follows:1. Carbaryl exerts inhibition on seeds germination and the roots elongation of several common crops. The germination rates was decreased follow the increase of exposure dose. The hemi-inhibitory concentration (EC50) values for different crops in response to carbaryl were 1097ppm (mung bean), 23.13ppm(wheat), 23.7ppm(radish), 38.45ppm (sorghum), 68.33ppm (cucumber), and 63.38ppm (spring onion), respectively. The EC50 values for the tap root system crops is larger than the fibrous root system crops, that is to say, the fibrous root system crops were more sensitive to carbaryl than the tap root system crops.2. The 24h, 48h and 72h LC50 of carbaryl to earthworm (E. foetida) were 324.2ppm (R~2=0.9798), 15.8ppm (R~2=0.9517), and 2.5ppm (R~2=0.9804), respectively. The concentration and exposure time were the main factors on toxicity of carbaryl, and the acute toxicity of carbaryl belongs to moderate toxicity.3. The degree of DNA damage was caused in all the treated groups. The degree of DNA damage became large obviously in accordance with the increase of exposure dose of carbaryl under the same exposure time. The damaged nucleus had a long comet tail in the treated group with high concentration of carbaryl.The results indicated that carbaryl could inhibit the roots elongation of experimented crops, cause the DNA damage or even the death of earthworms in short time period at low concentration. The concentration and exposure time were the main toxicity factors of carbaryl. Therefore, the both two factors should be taken into consideration when spraying carbaryl pesticides on crops. Pesticides have been the primary means and measures to prevent and control the agricultural pests and diseases. They have brought a series of problems such as environmental pollution, ecological balance destruction and food security. The current study explored the reasons and puts forward the issues in the use of pesticide and environmental management, rebuilt a correct understanding of pesticide.