Study On The Toxic Effects Of Three Formulations Rotenone On Mud Carp And Earthworm And Environmental Safety Evaluation

The safety of pesticides on non-target organisms is an important index of pesticide on the ecological environment impact evaluation. Rotenone is one of the most widely used botanical pesticides in our country at present. The application amount of rotenone is rising every year and emulsifiable concentrate?EC?, micro emulsions?ME?and suspension concentrate?SC?is one of the main three type formulations. Different formulations may have different biological processes in the environment and lead to the different environmental toxicity and behavior. This research selects the main environmental matrix such as soil, water, fish, worms and duckweed in the aquatic ecosystems. The assimilation, accumulation and toxic effects of three formulations rotenone?EC, ME and SC?in mud carp was investigated and the toxic effects of three formulations rotenone on earthworm as well the accumulation effect in the organisms, duckweed, soil, water and other environmental materials was studied.The toxic effects of three formulations rotenone on mudcarp and earthworms were evaluated. Results showed that significant difference between three formulations and the lethal dose(LC₅₀)of the three formulations at 24 h was 109.74, 136.64 and 153.05 ?g/L for EC, ME and SC, respectively. However, the LC₅₀ of earthworms in water was high as 2.31³.48 mg/L. This may suggests that the species significantly influence the effect of rotenone. Comparison of three formulations rotenone virulence of earthworms in the water and soil as you can see, the rotenone applied in the water environment showed more poison activity than in the soil, which can also be told that the environment can significantly affect the effect of the pesticide.The contents change in various tissues and organs in the poison and recovery process were detected by high performance liquid chromatography?HPLC?. Treated group were exposed with ₅₀ ug/L rotenone diluted in freshwater, the content of rotenone the in the whole fish EC, ME and SC is 0.78 mg/kg, 0.49 mg/kg and 0.32 mg/kg afrer 24 h. The highest enrichment ratio of EC in fish up to 15 times. The three rotenone concentrations in gills, scales, muscles, eyes, head, and intestines also detected. The results showed that the enrichment concentration of EC in both of the organizations are higher than that of ME and SC. In addition, from the distribution rate of three formulations in organizations, the ratio of rotenone in muscular tissue were more than 70%. When put the turn white poisoning fish in plenty of water, as the growth of the time, the fish will slowly back to normal, take advantage of this feature, tested the change of rotenone content from the three formulations in various organizations in the recovery process, fish recovery process was mainly completed within 15 minutes. 15 minutes after, EC, ME and SC in fish recovery rate was 73.01%, 88.95% and 93.20%, respectively. The rotenone content in the tissues and organs was also falling fast. Using paraffin section H.E. Stain method to observe the influence of the three formulations on muscle, eye, gills, and intestinal and results show that the three kinds of formulations could lead to different degrees of severity in various tissues and organs.We also explored the enrichment behavior of three formulations rotenone in the environment, such as water, soil, duckweed. According to the results of three formulations, we found that the bio-accumulation of EC was higher than that of ME and SC. The existence of aquatic organisms such as fish, earthworms can significantly accelerate the degradation of rotenone. Three formulations rotenone has a half-life of 23.70²5.32 h in the blank water, but put the duckweed and fish into the simulation ecological environment, the half-life of three formulations rotenone was 2.84 h⁸.28 h. Compared the half-life of the two treatment groups, we will find that there was a significant difference.The toxic effects of three formulations rotenone in aquatic ecosystems and soil ecosystem was studied. Results showed that the toxicity of rotenone in aquatic ecosystems was higher than the soil ecosystem. The amount of enrichment of rotenone in earthworm body in the water was much higher than in the soil in the same period. In addition, the degradation ability of earthworms to three formulations rotenone was also studied by the soil testing method. The three formulations rotenone in the the soil absence of worms has a half-life of 1.85 d, 2.79 d and 2.01 d for EC, ME and SC, respectively, and the half-life in the soil with worms were 0.81 d, 1.10 d and 1.29 d. Using optical microscope to observe and compare the earthworm skin tissues morphology change after treated with different formulations rotenone for 1d, the result within 1d showed that three formulations rotenone could harm the earthworm outer epidermis, EC and ME damage was more serious.In this paper, the research results showed that different formulations rotenone possessed significantly different biological activity. One of the important reasons of why rotenone high toxicity to the fish was that rotenone could enter the body form gills and penetrated the fish muscle tissue, finally, leaded a large number of enrichment in the fish body. At the same time, put the poisoning fish in a large amount of clean water, fish can release rotenone to external environments from different tissues and organs, such as to complete the body eliminate the effect of rotenone; on the other hand, different formulations also affected the rotenone degradation in soil, the presence of earthworms can significantly speed up the degradation of rotenone, But rotenone could also produce harm to earthworms, the toxicity effect of rotenone in the water environment is higher than in the soil. The research also provided theoretical guidance and scientific advice for the use of rotenone EC, ME and SC.