Preliminary Study On The Prevention And Control Techniques Of Plant Essential Oil And Inert Powder Against Sitophilus Zeamais

Sitophilus zeamais is the largest stored grain pest in China,and its damage will seriously reduce the quality of stored grain.At present,the chemical pesticide control,which is mainly relied on,will cause pest resistance,resulting in an increasingly serious“3R”problem.Therefore,it is of great significance to develop green and friendly new botanical insecticides to control stored grain pests.This experiment mainly studied the fumigation,contact and repellent effects of Mentha piperita oil,Cinnamomum cassia oil,Allium sativum oil,Illicium verum oil on adult S.zeamais.A.sativum oil with the best comprehensive effect was selected to determine its comprehensive toxicity to S.zeamais under different temperature conditions and whether wheat was added.The control effect of food-grade inert powder on S.zeamais at different temperatures,A.sativum oil and inert powder were mixed in different proportions,and their control effects on adult S.zeamais at different temperatures were determined to determine the best formula of the compound.It provides a scientific basis and preliminary basis for the subsequent application of green prevention and control technology of stored grain pests.The main results are as follows:1.Preliminary screening of prevention and control effect of four plant essential oils on S.zeamais1)Preliminary screening of repellent effect of 4 plant essential oils on S.zeamaisThree doses of 0.1,0.2 and 0.3μL/cm²were set,and the repellent effects of four essential oils on S.zeamais were garlic A.sativum oil>C.cassia oil>M.piperita oil>I.verum oil.At the dose of 0.2μL/cm²the average repellent rates of C.cassia oil and A.sativum oil at 96 h were 61.00%and 69.40%,respectively,and the repellent grades were all grade IV,while the average repellent rates of M.piperita oil and I.verum oil were57.80%and 53.13%,respectively,and the repellent grades were all grade III.2)Preliminary screening of contact toxicity of 4 plant essential oils on S.zeamaisThree doses of 0.3,0.6 and 1.2μL/cm²were set,and the contact killing effect of four plant essential oils on S.zeamais was A.sativum oil>C.cassia oil>I.verum oil>M.piperita oil.At the dose of 0.3μL/cm²,the corrected mortalities of A.sativum oil,C.cassia oil,I.verum oil and M.piperita oil to S.zeamais at 60 h were 50.00%,47.78%,34.43%and 33.33%,respectively.3)Preliminary screening of fumigation effect of 4 plant essential oils on S.zeamaisThree concentrations of 2,8 and 14μL/L were set up,and the fumigation effectof four plant essential oils on S.zeamais was A.sativum oil>C.cassia oil>M.piperita oil>I.verum oil.At the dose of 8μL/L,the corrected mortality of A.sativum oil,C.cassia oil,M.piperita oil and I.verum oil to S.zeamais at 48 h was 98.75%,94.75%,85.00%and68.75%.The above preliminary screening results showed that A.sativum oil had the strongest comprehensive effect on S.zeamais,so A.sativum oil was selected as the followup experimental material.2.Determination of fumigation effect of A.sativum oil on S.zeamais under different conditions1)Fumigation effect of A.sativum oil on S.zeamais at different temperaturesSix concentration gradients of 0.8,1.4,2.0,2.6 and 3.2μL/L were set.At 24 h after treatment,the LC₅₀of S.zeamais adults were 2.01,0.78 and 0.80μL/L at 20°C,27°C and35°C,respectively.The results showed that the fumigation effect of A.sativum oil on S.zeamais adults was significantly different at different temperatures.The fumigation effect of 27°C was the strongest,followed by 35°C and 20°C.2)Fumigation effect of A.sativum oil on S.zeamais under grain mixing conditions Seven concentration gradients of 4,10,16,22,28,34 and 40μL/L were set.At 24,48and 72 h after treatment,the LC₅₀of S.zeamais adults after adding wheat were 31.82,9.15and 6.28μL/L,respectively,and the LC₅₀of S.zeamais adults without adding wheat were2.75,1.21 and 0.78μL/L,respectively,indicating that the added wheat had a strong adsorption effect on the essential oil,would weaken the fumigation effect of A.sativum oil on S.zeamais.3.Determination of the different control effect of inert powder on S.zeamais at different temperaturesSix dose gradients of 50,100,150,200,250 and 300 mg/kg were set up,and the LD₅₀of S.zeamais adults were 78.04,58.01 and 71.81 mg/kg at 20°C,27℃and 35°C for 72 h.The results showed that the control effect of inert powder on S.zeamais adults was the best at27°C,followed by 35°C and 20°C.4.The optimal ratio of A.sativum oil and inert powder to control S.zeamais at differenttemperaturesThe mass ratio of A.sativum oil to inert powder was set as 1:50,2:50,1:100,1:150,2:150,1:200,1:250,2:250 and 1:300.At 20°C,27°C and 35°C,the higher the temperature,the better the effect on S.zeamais,and the optimal ratio of A.sativum oil to inert powder was 2:50.At 35°C,the corrected mortality of S.zeamais treated with this ratio for 21 days was higher than 85%,which had strong persistence.In this study,efficient plant essential oil--A.sativum oil and food-grade inert powder screened were made into a mixture at an optimal ratio of 2:50 and applied to the prevention and control of stored grain pests such as S.zeamais.The use of food-grade inert powder as a carrier for adsorbing essential oil can play a sustained-release synergistic effect,which is in line with the concept of green prevention and control,and provides a certain direction for the development of economical and friendly new grain storage pest control technology.