Study On The Toxicity Effect Of Chlorpyrifos And Beta-cypermethrin On Vibrio Fischeri And Eisenia Foetida

Recently,with the development of agricultural economy,the utilization of pesticides has also greatly increased,which will inevitably cause toxicity to non target organisms in natural ecosystems,harming to the structure and function of ecosystem.Moreover,the ecological toxicological effects caused by different pesticides have also attracted extensive attention accompanying.This main study of this paper includes that:（1）The test was conducted to evaluate the 15min and 30min acute toxicity effect on vibrio fischeri of single and mixed sample of chlorpyrifos and beta-cypermethrin on mixed ratio of 1:1、3:2 and 2:3.The Toxic Unit（TU）method,Additive Index（AI）method and Mixtures Toxicity Index（MTI）method were used to evaluate the joint toxicity.（2）The artificial soil method was utilized to study the acute toxicity effect on eisenia foetida of single and mixed sample of chlorpyrifos and beta-cypermethrin on mixed ratio of 1:1、3:2 and 2:3,using Additive Index（AI）method to evaluate the joint toxicity.（3）Study on the change of earthworm protein content,superoxide dismutase（SOD）,peroxidase（POD）and catalase（CAT）activity and malondialdehyde（MDA）content after poisoned by different concentrations of chlorpyrifos and 4 mg·kg^-11 of beta-cypermethrin under the sublethal dose,to explore the single and combined effects of chlorpyrifos and beta-cypermethrin on the physiological and biochemical indexes of earthworms.The test results are as follows:（1）The acute toxicity experiments of vibrio fischeri showed that the15min and 30min-EC₅₀0 of chlorpyrifos and beta-cypermethrin to vibrio fischeri were 35.37,38.29 mg·L^-11 and 124.82,127.39 mg·L^-11 respectively.The joint toxicities of chlorpyrifos and beta-cypermethrin were partial additive effects and synergistic.The evaluated results by Additive Index（AI）method was slightly different from the Toxic Unit（TU）method and Mixtures Toxicity Index（MTI）method.（2）After 7d,14d and 21d poisoned by chlorpyrifosm and beta-cypermethrin,the LC₅₀0 value were 374.28,351.41,318.65 mg·kg^-1and 669.17,483.73,335.21 mg·kg^-1respectively.The higher ratio of chlorpyrifosm in mixed sample would enhance the toxicity of beta-cypermethrin.（3）Under the single action of chlorpyrifos,the protein content of earthworms increased first and then decreased with the increase of exposure concentration;the activity of SOD and POD showed the trend of low concentration promotion and high concentration inhibition;the activity of CAT showed a trend of decreasing at first,then increasing and then decreasing with the extension of exposure time;the content of MDA increased with the increasing exposure concentration when exposed to 14 d,and when exposed to 21 d,it gradually tended to change in the level of the control group.Under the single effect of beta-cypermethrin,the content of protein in earthworm at low concentration and long time exposure was similar to that of high concentration and short time exposure;the activity of SOD showed a trend of increasing first and then decreasing;the activity of POD reached the maximum value at 10 mg and L^-1,and then decreased with the extension of exposure time;the activity of CAT decreased first and then increased during the exposure time;the content of MDA increased first,and then it decreased gradually tended to the level of the control group when exposed to 14 d.（4）Under the the joint toxicity of different concentrations of chlorpyrifos and 4 mg·kg^-11 of beta-cypermethrin,the protein content in earthworms decreased first and then increased;The activity of SOD was significantly inhibited,showing a trend of decreasing first,then increasing and then decreasing;The activity of POD showed a trend of increasing first,then decreasing and then increasing with the increase of exposure concentration;the CAT activity gradually decreased with the increase of exposure concentration and the prolonged exposure time;The change of the content of MDA was similar to the single effect.（5）According to the test results of the single and joint toxicity effects of chlorpyrifos and beta-cypermethrin on antioxidant enzymes and the content of MDA in eisenia foetida under sublethal doses,SOD,POD and CAT can be used as biological indexes to determine the degree of earthworm organism injury caused by chlorpyrifos and beta-cypermethrin pollution,and the content of MDA is not suitable as a biological indicator for organism to suffer oxidative stress.