Study On The Control Effect Of Beta-cypermethrin Mixed With Matrine On Plutella Xylostella L.

Plutella xylostella is one of the most important pests of cruciferous plants in the world.In order to delay the resistance of drug and reduce the use of drug,the optimum ratio of 4.5%beta-cyhalothrin EC and 1.3%matrine was screened out through this study.Then in order to achieve efficient and economical control of Plutella xylostella,the writer took advantage of the method of field test to explore the control effect of mixed preparation of Plutella xylostella.In addition,this study determined the effective dose range of the control effect of 4.5%effective cyhalothrin emulsion and 2.5%effective cyhalothrin emulsion at 0.50 times,0.75 times and 1.00 times of the recommended median(X)concentration on Plucella xylostella by laboratory test and field test.And it is also in order to provide the basis for the reduction of dosage.The contents and the main research results are as followed:(1)The indoor virulence of the third instar of diamondback moth was measured by leaf dipping method.After treatment for 48h,the LC50 value of 4.5%efficient cyhalothrin emulsion was 4.839 mg·1-1,1.3%matrine aqueous chamber was 63.791 mg·1-1.On this basis,the best ratio was selected.The results showed that when the ratio of 4.5%beta-cyhalothrin and 1.3%matrine was 6:4,the synergistic effect of it was the best,and the cotoxicity coefficient reached 265.(2)Field control experiments were conducted on 250 times liquid,500 times liquid,1000 times liquid of the best mixture and the control agent 4.5%high-efficiency cyhalothrin emulsion 500 times liquid and 1.3%matrine water 500 times liquid.The results showed that the control effects of 4.5%beta-cyhalothrin and 1.3%matrine mixture on Plutella xylostella were more effective than the control agents under the same condition.In this experiment,the toxicity of 1.3%matrine water and 4.5%beta-cyhalothrin emulsifiable concentrate was enhanced,and the content of beta-cyhalothrin in the compound was significantly reduced,so as to achieve the purpose of synergism and reduce the use of chemical pesticides.Taking into account the cost and efficacy,it is recommended that every 667 m2 in the field was recommended as 1000 times the amount of 4.5%beta-cyhalothrin and 1.3%matrine water mixture.(3)Potted experiment was carried out on Plutella xylostella with 4.5%beta-cyhalothrin emulsion and 2.5%efficient cyhalothrin emulsion in 0.50X,0.75X,1.00Xand 1.50X conditions.The results showed that 4.5%beta-cyhalothrin emulsion was more than 85%,and 2.5%efficient cyhalothrin aqueous emulsion was more than 85%effective in 1.50Xconditions.On this basis,field efficacy tests were carried out,and the results showed that the control effects in 0.50X,0.75X and 1.00 X after 7d,4.5%beta-cyhalothrin emulsion were 69.72%,79.55%and 80.81%,4.5%beta-cyhalothrin emulsifiable oil can achieve better control effect under the condition of reducing dosage.