| Thrips palmi Karny is an important pest of solanaceae and cucurbitaceous plants as eggplant and cucumber, since it can breed for the whole year, and its growth is extremely fast, therefore, it affects the yield and quality of solanaceae plants and cucurbitaceous plants, resulting in serious economic losses. At present, the prevention and control of thrips palmi Karny in agricultural production largely depend on the chemical pesticide, which has become a serious obstacle to the extension of pollution-free vegetables.In my study, I have selected plant extracts, pathogenic microorganism, microbial pesticides and so on, which has 14 kinds of biological pesticide in sum. Thrips palmi Karny as the research object for indoor toxicity and field test, I have explored spinosad in cucumber fruits residue detection method. The main results are as follows:1. Choosing 2-instar larvae of Thrip palmi Karny, plant extracts, microbial pesticides as tested pesticides, I made use of leaf dipping method for indoor toxicity determination. When pesticides were used to against the 2-instar larvae of Thrip palmi Karny after 24h and 48h treatment, the results showed the sequence of LC50, that is, spinosad>avermectin>pyrethrin>veratridine>rotenone>imidacloprid>osthol>azedarachin> stemona>celastrus angulatus>matrine>nicotine. Pathogenic microorganisms as tested insecticides, I used insect dipping method for indoor toxicity determination, the sequence of LC50 were:Bacillus thuringiensis>Green muscardine fungus>Beauveria bassiana, when the provided pesticides were used to against the 2-instar larvae of Thrip palmi Karny after treatment 5d, LC50 of Beauveria bassiana, Green muscardine fungus and Bacillus thuringiensis were 2.03 X 1011/L,1.71 X 1011/L and 7680.21mg/L respectively;after treatment 7d, LC50 were 5.51 X 1010/L,2.13×1010/L and 64.41mg/L respectively.2. The field efficacy trials were conducted by spraying method. The effects of 480 g/L spinosad SC was the best, after 1 day’s pesticide treatments, the control efficiency can reach 83%, the duration of the control efficiency could persist a long time. After 7 days, the control efficiency still can reach to 84.80%.1.5% pyrethrin EW 69 g/ha,10% nicotine EC 2700 g/ha,1.3%matrine AS 2700 g/ha,0.5% veratridine SL 8.44 g/ha, there are also have certain effects,1.5% pyrethrin EW 69 g/ha, after 1 day’s pesticide treatments, the control efficiency can reach 60.07%, after 3 day’s pesticide treatments, the control efficiency decreased. After 3 day’s pesticide treatments, the control efficiency of 10% nicotine EC 2700 g/ha is lower, after 3、7day’s the control efficiency was more than 70%. After 3 day’s pesticide treatments, the control efficiency of 1.3%matrine AS 2700 g/ha and 0.5% veratridine SL 8.44 g/ha can reach to 60%, but the period of protection is short, after 7 day’s, the control efficiency decreased. The effects of 3000IU/mg Bacillus thuringiensis WP 9000 g/ha, two billion/g Green muscardine fungus WP 6750 g/ha are slow, after 14 day’s pesticide treatments, the control efficiency can be reached more than 60%. Recommended dosage is:480 g/L spinosad SC 18～36 g/ha,1.5%pyrethrin EW 69 g/ha,10%nicotine EC 2700 g/ha,1.3%matrine AS 2700 g/ha,0.5%veratridineSL 8.44 g/ha,3000IU/mg Bacillus thuringiensis WP 9000 g/ha, two billion/g Green muscardine fungus WP 6750 g/ha.3.The method was established for the determination of spinosad residue in cucumber fruit by HPLC-UVD, its accuracy and precision can meet the requirements of pesticide residue analysis. Through the field test the spinosad in cucumber fruits residue dynamics were monitored, the results of the study showed that, in the field, the spinosad degradation accorded with the first-order kinetics equation, the kinetics equation was Ct=1.6298e-0.249t(R2=0.997),the half-life of spinosad in cucumber fruits was 2.78d,less than 30d, that means spinosad degradation speed, belongs to easy degrade pesticide. At the same time, after spraying 5d, spinosad residues are lower than the maximum residue limits. |
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