Environmental Safety Evaluation Of Botanical Pesticide Toosendanin

Toosendanin pesticide is a good kind of botanical pesticide with high insecticidal activity, multiple action modes, broad spectrum and unique mechanism. Based on the result of Huanan Agriculture University, 0.5% toosendanin EC was developed by R& D Center of Biorational Pesticide, Norwest A & F University. This dissertation focused particularly on the studies of environmental safety evaluation of the two toosendanin-based products: 78% toosendain powder and 0.5% toosendanin EC.1. The safety of toosendanin to seven species of environmental organism was evaluated, according to"Experimental Guideline for Environmental Safety Evaluation of Chemical Pesticide". The results showed:(1)The acute LD₅₀ of 78% toosendanin powder and 0.5% toosendanin EC to quai(lCoturnix chinensis)was 158.544 and 17.951mg/Kg respectively. The powder was low toxic to quail. The EC was moderate toxic to quail. The accumulative coefficient of both was 5.96.(2)Both toosendanin powder and EC were no apparent contact toxicity to silkworm(Bombyx mori). The acute LC₅₀ of them was more than 200mg/L. They had some negative effect on silkworm's growth and developing.(3)Toosendanin powder and EC both were low toxic to be(eApis mellifera). Acute contact LD₅₀ of toosendain powder and EC to bee was 6543.989 and 973.301μg/bee, respectively. Acute oral LD₅₀ of them for bee was 3678.969 and 154.072 mg/L, respectively.(4)Toosendanin powder's LC₅₀ to earthworm was more than 5000 mg/L. Toosendanin EC's LC₅₀ to earthworm was between 100 and 200mg/L .Both of them were low toxicity.(5)The toosendanin powder and EC were no apparent contact toxicity to ladybeetle(Coccinella septempunctata). The LC₅₀ of toosendanin powder for ladybeetle was more than 5000mg/L, The LC₅₀ of toosendanin EC was 1370mg/L. (6)The LC₅₀ of toosendanin powder to tadpole(Rana limnochris)was more than 10mg/L. The LC₅₀ of toosendanin EC to tadpole was 0.443mg/L. The powder was low toxic to tadpole. The EC was highly toxic to tadpole. 78% Toosendanin powder was low toxic to quail, silkworm, bee, earthworm, ladybeetle, tadpole and soil microbe; 0.5% toosendanin EC was low toxic to silkworm, bee, earthworm, and ladybeetle and soil microbe. Its toxicity to quail was moderate, to tadpole was high.2. The affection of toosendanin to respiration, ammoniation, nitrification and nitrogen-fixing bacteria of soil microbe were studied. The result showed: toosendanin powder was no apparent inhibition to respiration of soil microbe. High concentration of toosendanin EC had some effect on respiration of soil microbe. High concentration of toosendanin EC had some effect on ammoniation and nitrification of soil, however, toosendanin powder had no effect on them. Toosendanin EC had hardly affection, but toosendanin powder had some effect on nitrogen-fixing bacteria in vegetable field and flower field and no apparent regular pattern.3. In Chapter 4, The mothed for determination of residues of toosendanin in tapes water and soil by high performance liquid chromatography (HPLC) was established Toosendanin recoveries determined in tapes water and soil by HPLC were both more than 75%.4. Adsorption of soils to toosendanin by oscillation balance method was tested. The result showed:Toosendanin was adsorbed by soil in water-soil system, and it was found that adsorption process of toosendanin in three kinds of soil was fitted to Freundlich(R2>0.953).5. The degradation of toosendanin in different soils and water was studied by HPLC from Chapter 6 to 7. The results showed that: Degradation rate of toosendanin was both fast in non-sterilized soil and sterilized soil, but toosendanin depletion was faster in sterilized. Abiotic hydrolysis of toosendanin in different water had related to dielectric pH value. In Ph 5 and pH 9 solutions, the half-life of toosendanin were 17.748 and 13.899d, respectively. Hydrolytic rate of toosendanin was very slow in neutral. The half-life of toosendanin was 26d. The studies on environmental fate of toosendanin that toosendanin degrade fast in soil and water, and it is lower persistent in environmental media.