Toxicological Effects Of Chlorpyrifos And Atrazine On Salamandrella Keyserlingii And Hynobius Leechii

In recent years,there is a trend of the sharp declining number of amphibians in the world.Studies have shown that the decrease of amphibians to some extent is related to the polluted environment,and the heavy usage of pesticides is the key reason for environmental pollution.In this study,two common amphibians in northeast China?Salamandrella keyserlingii and Hynobius leechii?are chosen to be the research objects and the common herbicide atrazine and chlorpyrifos are used to be infected objects so as to test the acute toxicity,growth toxicity,oxidative stress damage of these two kinds of pesticides to tadpoles with the tail.Meanwhile,the pathological damage of tadpole muscle and liver caused by two pesticides was analyzed from the perspective of pathology by HE staining.The results of acute toxicity test showed that the 96 h LC₅₀0 of atrazine to the tadpoles of Salamandrella keyserlingii and Hynobius leechii was 2.63 mg/L and 4.29mg/L,respectively;the 96h LC₅₀0 of chlorpyrifos to the tadpoles was 0.11 mg/L and0.16 mg/L,respectively;and the 96 h LC₅₀0 of the mixed solution to the tadpoles of Salamandrella keyserlingii and Hynobius leechii was 0.18 mg/L and 0.28 mg/L,respectively.The growth toxicity test showed that atrazine and chlorpyrifos could inhibit the length and weight of tadpoles whether they were single exposure or combined exposure,and the higher the concentration,the greater the inhibition.The inhibition rates of tadpole length and weight of Hynobius leechii at the end of exposure were atrazine15.3%and 17.2%;chlorpyrifos 16.2%and 18.4%;mixed solution 22.6%and 34.6%.The inhibition rate of each exposure group on the length and weight of the tadpole of Salamandrella keyserlingii were as follows:atrazine 15.1%and 18.1%;chlorpyrifos17.6%and 24.7%;mixed solution 27.6%and 34.8%.With the increase of the exposure concentration and the exposure time,the content of SOD,CAT and GSH-PX decreased as a whole and the content of MDA increased gradually.At the end of exposure,compared with the control group,the content of SOD,CAT,and GSH-PX of the tadpoles,Hynobius leechii reduced by 32.6%,58.8%,29.6%,and that of the tadpole of Salamandrella keyserlingii reduced by 52.3%?73.4%?54.3%,respectively.HE staining results showed that after being poisoned,some phenomena of enlargement hepatocyte,decreased chromatin,inflammation of muscle tissue,broken muscle fiber,disintegration and so on emerged in the tadpoles of Salamandrella keyserlingii and Hynobius leechii.It was found that by the recovery of the experiment,the body to some extent was partially repaired whether from the view of growth and development,histopathology or autioxidant enzyme activities when the environment gets improved.The toxicological impacts of atrazine and chlorpyrifos on tadpoles of Salamandrella keyserlingii and Hynobius leechii were studied in different ways in this study,which enriches the effects of pesticides on the toxicology of amphibians,and at the same time,the author hopes to provide an important theoretical basis for the reasonable usage of pesticides and environmental protection of amphibians.