The Toxic Effects Of Cypermethrin And Imidacloprid On Procambarus Clarkii

In this paper,the toxic effects of Cypermethrin and Imidacloprid on the freshwater prawn.Procambarus clarkii,were investigated.The main research contents included:acute toxicity tests of Cypermethrin and Imidacloprid on Procambarus clarkii;the effects of a sub-lethal concentration of Cypemethrin and Imidacloprid on some physiological indexes of Procambarus clarkii,includingOxygen consumption,ammonia-N excretion rate,AChE and Na⁺,K⁺-ATPase activities,and some immune-related enzymes(acid phosphatase,alkaline phosphatase,lysozyme) activities,and some antioxidant enzyme(superoxide dismutase,catalase,glutathione S-transferase) activities.Each experimental index was synthesized and analysed the toxic effects of two pesticides on Procambarus clarkii.The results would provide the scientific reference basis for evaluating pesticides to safety of aquatic animals.The static acute toxicity test results showed that the LC₅₀ of Cypermethrin and Imidacloprid for 96 h were 0.063mg/L and 10.98mg/L to Procarnbarus clarkii,the Sc of Cypermethrin and Imidacloprid were 0.0063mg/L and 1.10mg/L.It was showed that Cypermethrin was more poisonous to Procambarus clarkii than Imidacloprid.According to results of acute toxicity test,six concentrations were putted up in the range of 0-96h LC50,the experiment lasted for 24h,Then each experimental index were measured.Main conclusions are drawn as follows:With the increasing concentrations of Cypermethrin,both of the oxygen consumption rate and the ammonia-N excretion rate were decreased.However,with the increasing concentration of Imidacloprid,the oxygen rate tended to raise first and then declined,the ammonia-N excretion rate had decreased.It was showed that Procambarus clarkii has different way to adapt the toxic effect on the respiration metabolism.Two sub-lethal concentration pesticides induced AChE activities, Na⁺,K⁺-ATPase activities were inhibited when Procambarus clarkii were exposed to sub-lethal concentration Cypermethrin.But when Procambarus clarkii were exposed to Imidacloprid,Na^-,K⁺-ATPase activities were inhibited at lower concentrations and were induced at higher concentrations.When Procambarus clarkii exposed to Cypermethrin,with the increasing concentrations of Cypermethrin.the ACP activities of gill and hepatopancreas tissues were higher generally than the blank group,the AKP activities of gill tissues first rised and then declined,but the AKP activities in hepatopancreas tissues was inhibited all the time.LSZ activities of gill first decreased and then rised.But when Procambarus clarkii exposed to Imidacloprid,the phosphatase activities of gill and hepatopancreas tissues took on contrary changes.LSZ activities of gill showed lower than blank groups generally.When Procambarus clarkii exposed to Cypermethrin,with the increasing concentrations of Cypermethrin,the SOD and CAT activities of muscle tissue were inhibited and decreased obviously,the GST activities of muscle tissue were induced and increased.The CAT and GST activities in hepatopancreas tissues were inhibited and decreased,the SOD activities in hepatopancreas was induced and increased significantly.But when Procambarus clarkii exposed to Imidacloprid,only the SOD activities of muscle took on first increased then decreased,the others decreased in lower concentrations and increased in higher concentrations,and the enzymes activities in hepatopancreas tissue higher than in muscle tissue.