| Beet armyworm is the main insect pests worldwide, which does harm to a variety of cruciferous vegetables. At present, the beet armyworm control measures are mainly chemical control in China. However many serious consequences have been caused by the long-term using chemical pesticides. In order to reduce and delay the generation of the beet armyworm insecticide resistance, people began to use botanical insecticides. Mulberry contains a variety of bioactive substances, such as DNJ and quercetin, which could effectively inhibit glycosidase activity and could greatly reduce the harm of lepidoptera pests on crops. In this paper, taking mulberry powder as raw material and optimize the extraction process. The test is to compare the weight of the crude extract in anhydrous ethanol, acetone, n-butanol, ethyl acetate and tetrachloromethane, and then using liquid chromatography (HPLC) to measure the DNJ and quercetin content in each crude extract. Different contents of crude extract in water. The control group is water. The main results are as follows:1. Using anhydrous ethanol as a solvent for extraction process optimization. Conclusion: ultrasonic wave extraction method> soaking extraction method> cold-soaked extraction method.2. Extracted by ultrasonic extraction. Five kinds of solvents for extraction were compared, they are anhydrous ethanol, acetone, ethyl acetate and n-butanol, and tetrachloromethane. Conclusion:anhydrous ethanol> n-butanol> tetra chloromethane> ethyl acetate> acetone. Use HPLC to analyze the above five kinds of crude extract solvent. Conclusion:(1) DNJ extraction rate:anhydrous ethanol> tetrachloromethane> n-butanol> acetone> ethyl acetate.(2) the quercetin extraction rate:anhydrous ethanol> tetrachloromethane> acetone> ethyl acetate> n-butanol3. Extracted by ultrasonic extraction, with40%ethanol,60%ethanol,80%ethanol and anhydrous ethanol compared. Conclusion:60%ethanol>80%ethanol>40%ethanol> anhydrous ethanol. Therefore, the experiments show that the ultrasonic extraction method,with the60%ethanol solvent, which is the optimal extraction scheme.4. Growth inhibition ratio of mulberry leaf extracts aqueous solution to beet armyworm larvae is about80%during the experimental period of48h-96h. Touch treatments have significant effect after24h. But the stomach toxicity shows significant effect in48hours. The stomach toxicity shows obvious effect after48h. Although stomach toxicity effect is slower than the tag effect, in each group of experiments, the experiment effect of stomach toxicity is better than that of touch.5. Through continuous spraying for120hours, with the continuation of the time, the beet armyworm larval mortality and corrected mortality rates experience upward trend. The above experiments illustrate that mulberry leaf extracts has a toxic effect on the beet armyworm, and the higher the concentration of mulberry leaf extracts is, the better the toxic effects on the beet armyworm will be. |
