Studies On The Effect Of Insecticide On Physiological Activities Of Fish

Lamba-cyhalothrin is a kind of synthetic pyrethroids, which proves to be effective, widespread and less poisonous so it is widely used to control insect pests in agriculture, and becomes the third most important insecticide after organophosphates and carbamates. Although it is a very effective insecticide and has little harms to chordate animals such as birds and mammals, yet such a thing is a deadly poison to aquatic such as fish. It has been suggested that synthetic pyrethroids are easily absorbed by the gills of fish even at very low concentrations. And because of its wide use, it will consequently affect fish cultivating and even the whole ecological cycle. The aim of the present study is to assess the toxic effects of Lamba-cyhalothrin on the Monopterus albus.Monopterus albus , popularly named eel, is a species of freshwater fish which belongs to eel subfamily, gill branch and gill item and which is very popular on account of its delicious taste. It has fairly capacity of anti-pollution; therefore, Monopterus albus was chosen as experiment subject in this experiment. At the beginning, the effectiveness of Lamba-cyhalothrin on the acute toxicity was studied .The 96hr LC50 of Lamba-cyhalothrin for Monopterus albus was 0.021μg/L. The Monopterus albus hepatic tissue homogenate was treated against Lamba-cyhalothrin levels of 0.0021μg/L,0.0035μg/L,0.0053μg/L,0.0106μg/L for exposure times of 48hr and 96hr.Then this experiment has studied the effect of Lamba-cyhalothrin on the activities of GOT, GPT, AChE, SOD, and GST in liver in Monopterus albus. In the end this experiment has studied the effects of Lamba-cyhalothrin on micronucleus and nuclear abnormity in the peripheral blood of Monopterus albus. The main results were summarized as follows:1.The half lethal concentrations of 24 hr, 48 hr,72 hr, 96 hr of Monopterus albus to Lamba-cyhalothrin were 0.0362,0.0320,0.0263,0.0213μg/L and the safety concentration were 0.00213μg/L. So the toxicity of Lamba-cyhalothrin on Monopterus albus was very strong.2.With the effects of Lamba-cyhalothrin, GOT and GPT activities of the Monopterus albus increased observably in lower concentrations and decreased in higher concentrations. With the concentration augmented or the time prolonged, the liver cells were serious damaged and even killed, and then the hepatic enzymes cannot be synthesized.3.With the concentration augmented or the time prolonged, the activities of liver AChE of Monopterus albus were dropped gradually, and the restraining degree gradually increased, the difference were significant at the 0.05 level(P<0.05) when all test groups compared with the control group.4.There was a dosage-effect relationship between Lamba-cyhalothrin concentrations and the activities of liver glutathione S-transferase (GST) of Monopterus albus. With the concentration augmented, the activities of GST were inhibited obviously first and second induced markedly and then inhibited to significant difference at the 0.01 level (P<0.01) with the control level.5. Micronuclei test of Monopterus albus was applied to study possible mutagenic activities of Lamba-cyhalothrin. The test results indicated that Lamba-cyhalothrin could increase the micronuclear rates, nuclear anomalies and total nuclear anomalies erythrocytes. At certain range of Lamba-cyhalothrin concentration, the frequency of micronucleated erythrocytes showed a dosage-dependent elevation. In addition, with the different times, the high frequency of micronucleated erythrocytes appeared also 0.0035μg/L, then the high frequency of nuclear anomalies erythrocytes droped gradually. In short, Lamba-cyhalothrin had mutagenic actions to the erythrocytes of Monopterus albus.These hepatic enzymes indices mentioned above and micronuclear rates could be considered as biological monitoring indices of Lamba-cyhalothrin pollution in aquatic ecosystems.In the thesis,Biomarker systematically and creatively studied the effects of the sublethal concentrations of Lamba-cyhalothrin (an synthetic pyrethroid)on the physiological,biochemical changes of the freshwater fish, Monopterus albus,which provides a theoretical and scientific basis for environments monitoring and fish cultivating.