| Cotton is an important industry pillar in Xinjiang.In recent years,Aphis gossypii has gradually become an important factor restricting the development of cotton industry.However,the long-term use of chemical pesticides has brought serious "3R" problems.It is urgent to find green,safe and efficient products to replace chemical pesticides.In this study,the biological activity of extracts against Aphis gossypii was determined,the plant resources with strong biological activity against Aphis gossypii were screened,the best extraction process was studied to improve the extraction efficiency,and the control effect of self-made extract EC of Datura stramonium against Aphis gossypii was determined,so as to lay a foundation for the development and application of botanical insecticides.The results are as follows(1)28 species of 18 families were collected from Xinjiang.The bioassay of methanol extracts against Aphis gossypii was determined by the method of dipping insects and leaves.The results showed that there were 8 plants with corrected mortality(24h)above 50%.Datura stramonium had the best insecticidal effect,followed by Hemlock,with corrected mortality(24h)of 75.18% and 69.76% respectively.(2)By comparing the effects of three different extraction methods on the extraction rate of methanol extract,ethanol extract,petroleum ether extract and ethyl acetate extract of Datura stramonium,it was found that the optimum extraction method and solvent were ultrasonic extraction and ethanol solvent,and the extraction rate was 11.29%.Through orthogonal test,the optimum extraction method of Datura stramonium extract was further determined,that is,85% ethanol concentration,extraction for 45 min,solid-liquid ratio of 1:10,repeated extraction for four times.(3)The results showed that four extracts of Datura stramonium had strong contact killing effect on Aphis gossypii,among which ethanol extract had the highest contact killing activity,followed by methanol extract,ethyl acetate extract and petroleum ether extract.The 72 h corrected mortality rates were 91.26%,90.71%,85.69% respectively 84.78%;The results showed that the extracts of Datura stramonium had a certain endosorbent effect on Aphis gossypii,but the activity was low.The ethanol extract had the highest endosorbent activity,followed by methanol extract,followed by petroleum ether extract and ethyl acetate extract.The absorption activity within 72 hours was 69.01%,53.34%,50.06% and 42.32% respectively.With the help of ultra performance liquid chromatography tandem mass spectrometry detection platform,a total of 675 metabolites of 13 categories in Datura stramonium plants were identified,among which the metabolites in seeds were the most,followed by leaves and stems;The biological activity of different parts of Datura stramonium against Aphis gossypii was determined,and the results showed that the seed extract had the strongest effect against Aphis gossypii.The results of the experiment and related literature are used to speculate that Anisodamine,Scopolamine,Anisodamine,Scopolamine,Scopolamine,and Anisodamine are the best α-Solanine,Norhyoscyamine,Anisodine α-Solanine and other seven alkaloids are the main insecticidal substances in Datura stramonium.(4)The formula of Datura stramonium extract EC was determined as follows: 15% crude extract of Datura stramonium,15% Tween-80,30% ethanol and 30% DMSO respectively,and the quality was qualified.The indoor control effect showed that the control effect of 50 and 100 times diluted solution of Datura stramonium extract EC was 75.93%,80.19%,62.31%and 70.47% respectively after 5 days and 7 days of application,which was far lower than 89.76% and 95.29% of the control group,indicating that the two pesticides had poor sustained effect,and there was still a partial gap compared with chemical pesticides. |
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