Study On The Toxic Effects Of Imidacloprid On The Liver Of African Clawed Frog

Neonicotinoids are some of the most widely utilized insecticides because they are highly effective against a variety of insects and are relatively nonvolatile and highly water soluble.Imidacloprid was extensively used to defend crops against insects.However,imidacloprid has the potential to contaminate surface water by entering water bodies from crops,affecting non-target aquatic organisms.Therefore,in this study,Xenopus laevis was selected to study the liver toxicity effect of imidacloprid.The contents and conclusions of the research are shown as follows:（1）Acute toxicity test of imidacloprid to the Xenopus laevis.The acute toxicity of imidacloprid to Xenopus laevis was investigated and the 96 h-LC₅₀ value for imidacloprid was 74.18 mg/L.The toxicity level of imidacloprid to the Xenopus laevis was classified as low,however,prolonged exposure to imidacloprid caused damage to the liver of Xenopus laevis.（2）A method for the determination of imidacloprid in the liver of the Xenopus laevis.LC-MS was used to detect imidacloprid content in water exposed to imidacloprid and in the liver of Xenopus laevis.The results showed that the concentration of imidacloprid in water was basically consistent during exposure.After28 days of exposure to imidacloprid,when exposed to high and low concentrations,the content of imidacloprid in the liver were 2.2424±0.1382 mg/kg and 0.2130±0.0061mg/kg,respectively.Prolonged exposure can cause imidacloprid to accumulate in the liver of Xenopus laevis.（3）Oxidative stress effects of imidacloprid in the Xenopus laevis.To investigate the effect of imidacloprid on oxidative stress in the liver of the Xenopus laevis,the enzymatic activities of SOD,CAT,GST,GSH-Px and MDA related to the antioxidant system were measured in the liver of Xenopus laevis exposed to different concentrations for different periods of time.The results showed that compared with the control group,the enzyme activity of SOD,CAT,GST,GSH-Px and the content of MDA were increased,indicating that imidacloprid induced oxidative stress of Xenopus laevis.（4）The effect of imidacloprid on the liver of Xenopus laevis was studied at the morphological level through histopathological observation.The Xenopus laevis was exposed to different concentrations of imidacloprid.After 28 days of exposure,the liver was employed for histological observation.Compared with the control group,the inflammatory cell infiltration,tissue congestion and cell necrosis were observed in the liver of Xenopus laevis.（5）Non-target metabonomics was used to study the toxic effect of imidacloprid on the liver of Xenopus laevis.After exposure to imidacloprid for 28 days,the liver of Xenopus laevis was employed for non-targeted metabonomics analysis.The results showed that the exposure to imidacloprid affected the changes of metabolism-related endogenous metabolites,thereby disrupting related metabolic pathways,suggesting that imidacloprid had an effect on the metabolism of Xenopus laevis.