Indoor Bioassay And Field Efficacy Of Three Plant-based Insecticides On Mythimna Separata

Mythimna separata(Walker)is one of the most important omnivorous crop pests in China,and its effective control is vital to crop production.At present,chemical pesticides are mainly used in the prevention and treatment of Mythimna separata in China.However,with prolonged use of chemical pesticides,the resistance of chemical pesticides in subsequent control has gradually increased,and the impact on the environment has become greater and greater.Therefore,in this test,botanical pesticides were mainly used for Indoor bioassay and field efficacy of corn Mythimna separata,in order to obtain a control agent with high activity against the Mythimna separata and envin order to obtain a control agent with high activity and environmental friendly against Mythimna separata.Based on the previous research basis,this study uses Mythimna separata as the test insect,and three botanical insecticides,matrine,veratridine,and azadirachtin as the test agents.Indoor insecticidal activity of the 3rd instar larvae and their field test effects on corn armyworms,with a view to providing theoretical basis for pesticide control of field insects such as Mythimna separata.The main research results of this experiment are summarized as follows:1.Taking the 3rd instar larvae of myxomycetes as the test object,the corrected mortality rate of myxomycetes larvae was measured after treated with matrine,veratrine and azadirachtin for 2,12,24 and 48 hours.Then,the LC50 of the three insecticides were obtained Matrine 32.845 mg / L,veratrine 126.015 mg / L and azadirachtin 48.254 mg / L.It can be seen from the above data that matrine is the best in the toxicity test of three plant pesticides,Azadirachtin is the second,while veratrine is the worst.2.On the basis of the indoor toxicity test,the field efficacy test was carried out for three kinds of chemicals: 2% matrine,0.5% veratrine and 1% Azadirachtin microemulsion.Each pesticide was set with three test concentrations of low,medium and high according to its recommended dose.The results showed that 1% Azadirachtin microemulsion had the best control effect,followed by 2% matrine and 0.5% veratrine.Compared with the results of indoor bioassay,the control effect of 1% Azadirachtin and 2% matrine in the field was slightly different from that of indoor bioassay.To sum up,comparing the test results of three kinds of botanical insecticides,i.e.2% matrine,0.5% veratrine and 1% Azadirachtin microemulsion,we can see that 1% Azadirachtin microemulsion has the best control effect in practical application.Therefore,based on this test,1% Azadirachtin microemulsion is recommended as the control agent in the future slime control.In the actual production,we can consider to add appropriate synergist,penetrant,stabilizer and other additives to improve the physical and chemical properties of the agent,so as to further improve its control effect.We can also improve the efficacy and delay the occurrence and development of insect resistance by screening the best combination way with three kinds of botanical agents.After screening out the synergism combination with better control effect,the synergism combination with better control effect can be developed according to the physical and chemical properties of different agents.