Biological Activity Of Isocycloseram Pyramid Against Diamondback Moth And Its Digestion Dynamics In Cabbage And Soil

Isocycloseram is a new type of isoxazoline insecticide developed by Swiss Syngenta Crop Protection Co.,Ltd.It is still in the stage of drug efficacy test,environmental safety evaluation and risk assessment in my country,registration certificate has not been approved.In this paper,on the basis of testing the indoor virulence and field control effect of isocycloseram against diamondback moth,an analytical method for the determination of effective components in isocycloseram 10%DC was established by HPLC.A method for the analysis of residues of isocycloseram in cabbage and soil was established by QuEChERS-HPLC,and carried out the digestion dynamic test of isocycloseram.The result are as follows:1.The virulence of isocycloseram against diamondback moth was determined by the leaf dip method in the room,and field control efficacy tests were carried out in 2019 and2020.The virulence regression equation of isocycloseram to diamondback moth is Y=5.7404+1.4363x,R~2=0.9940,the LC50 at 48 h after the drug is 0.2629 mg/L,the relative virulence index is 21.46,and the biological activity is much higher than that of the control drug Avermectin.The control effect of isocycloseram 10%DC agent 15-30 g ai/hm~2 treated the control of diamondback moth at 7 d and 14 d after treatment in 2019,which were82.37%-98.56%and 97.85%-99.02%,respectively;in 2020,which were 61.82%-96.79%and 76.71%-96.33%,respectively.The control effect was significantly higher than that of the control agent(1.8%Abamectin EC).Therefore,isocycloseram 10%DC is suitable for the field control of diamondback moth in cabbage.2.To establish an analytical method for the determination of active ingredients in isocycloseram 10%DC by HPLC.A Zorbax Eclipse XDB-C18 reversed-phase chromatographic column was used,with acetonitrile-0.1%formic acid water(volume ratio65:35)as the mobile phase,and the detection wavelength was 264 nm.The linear correlation coefficient(R~2)of isocycloseram was 0.9999,the standard deviation was 0.0152,the coefficient of variation was 0.1550%,and the average recovery was 99.70%.The analytical method has the characteristics of good linear correlation,simple operation,good precision and high accuracy,and can be used for qualitative and quantitative analysis of isocycloseram DC.3.An analytical method was established for the analysis of isocycloseram residues in cabbage and soil by QuEChERS-HPLC.The LOD and LOQ of isocycloseram in soil matrices were 0.0073 and 0.0245 mg/kg,respectively,and the LOD and LOQ of isocycloseram in cabbage matrices were 0.0090 and 0.0299 mg/kg,respectively.The matrix effects of soil and cabbage were-3.11%and 14.23%,respectively.The recovery rate of isocycloseram in cabbage is 91.67%-114.74%,the RSD is 0.40%-6.33%,the recovery rate in soil is 89.89%-104.08%,the RSD is 0.50%-6.46%.It can meet the requirements of isocycloseram residue analysis in cabbage and soil.4.The digestion dynamic test of isocycloseram was carried out in Jiangxi,China.The half-lives of isocycloseram in cabbage and soil in 2019 and 2020 were 2.50-2.88 d and 3.87-4.81 d,respectively.At the same time,the removal effects of different cleaning methods on the residues of isocycloseram in cabbage were studied.The removal rates of water immersion,ultrasonic cleaning and adding sodium bicarbonate were 18.44%-57.40%,20.46%-71.47%and 24.23%-59.62%,respectively.The removal rates of sodium chloride and citric acid were 43.67%-71.66%and 38.50%-73.20%,respectively.Therefore,choosing an acidic fruit and vegetable cleaner or adding sodium chloride can better remove isocycloseram residues on cabbage.