Ecotoxic Effects Of Ethiprole On Earthworms

Pesticides play an important role in reducing the loss of pests and diseases and ensuring the high yield and harvest of agriculture.They have become indispensable means of production in current agricultural production.However,when pesticides are widely used,they are harmful to soil ecosystems and non-target organisms.In this study,Eisenia foetida earthworm,a common non-target organism for evaluating soil pollution,was taken as the research object.The ecotoxic effects of ethiprole were studied at tissue,cell,molecule and gene expression levels in order to find out the more sensitive indicators to pollutants,so as to improve the ecotoxicological diagnostic indicators,establish a risk assessment technology system,and reasonably solve soil problems.The pollution problem provides a theoretical basis.(1)Individual level:Acute toxicity test showed that the 14d-LC₅₀ value of ethiprole to earthworms was 5000.2,95%confidence interval was 4344.6-5897.3,regression equation was Y=1.747X-6.464,R² was 0.954.The mortality of earthworms increased gradually with the increase of exposure concentration and exposure time.ethiprole is a low toxic pesticide to earthworms.(2)Cell level:The epidermis and intestinal tissues of poisoned earthworms were observed by microscopy.The results showed that the intestinal tract was severely damaged at 416.0mg/kg concentration on 21 days,the blind passage was lost,the longitudinal muscles were irregularly arranged,and the lower epidermis of 625.0 mg/kg was severely damaged at 7 days,the epidermis was not smooth,the cell spacing was enlarged,and the cells were not closely arranged.(3)Tissue level:The effects of ethiprole on antioxidant enzymes and malondialdehyde of Eisenia fetida were studied by artificial soil exposure.The results showed that the activity of SOD first increased and then decreased at 416.0 mg/kg and 625.0 mg/kg concentrations(except 28 days)and then decreased at 1000.0 mg/kg;the activity of POD was inhibited except at 416.0 mg/kg for 3 days and 625.0 mg/kg for 21 days;the activity of MDA was higher than that of the control group within 14 days of each treatment concentration,but after21 days,the activity was lower than that of the control group,at 416.0 mg/kg and 625.0mg/kg.The concentration of mg/kg increased significantly at 7 days.CAT was inhibited at concentrations of 416.0 mg/kg,625.0 mg/kg and 1000.0 mg/kg.At concentrations of166.0mg/kg,250.0mg/kg and 312.0mg/kg,it increased first and then decreased with the prolongation of exposure time,reaching its maximum at 14 days,indicating that CAT activity was more sensitive to pollutants.(4)Molecular level:The DNA damage of earthworm coelomic cells induced by ethiprole was studied by artificial soil method.The results showed that the degree of DNA damage(Olive tail distance,tail DNA content,tail length)first increased and then decreased with the increase of exposure time and concentration at each concentration,reaching the maximum at7 days,then gradually decreased after 7 days,and the higher the concentration,the slower the decrease,indicating that the DNA damage was at a lower concentration.Comet assay can also be used as an indicator biomarker sensitive to pollutants.(5)Gene expression level:Quantitative fluorescence polymerase chain reaction was carried out by artificial soil method.The results showed that SOD gene increased first and then decreased under ethiprole treatment.After ethiprole exposure,the expression of TCTP gene and HSP 90 increased at transcriptional level,reaching the maximum on the 7th and 14th day respectively,and the expression of l-r RNA gene remained inhibited with the increase of ethiprole concentration.