Synergies Control Of Reduced Insecticides And Insecticides Residues Against Myzus Persicae In Broccoli

As a wordwide omnivorous pest,Myzus persicae often causes physiological abnormalities by prickling plant juice,spreading plant virus disease and secreting honey dew.Because the insect body is small,it is not easy to be found when it occurs in the early stage,and with the increase of drug dosage year by year,the resistance is strengthened step by step.Therefore,M.persicae has become an important control object for vegetable production and management.In this study,the occurrence dynamics and spatial pattern of M.persicae were studied,which provided theoretical basis for the timely control of M.persicae in the production of Broccoli.On this basis,the toxicity of insecticides,synergistic effect and optimal ratio screening of compound,synergistic effect of insecticides reduction,and the actual control effect in the field was evaluated.Meanwhile,the dynamic effects of insecticides reduction in Broccoli.The major tests in this paper are listed as follows:1.Occurrence dynamics and spatial pattern of M.persicae in Broccoli fieldThe occurrence and spatial pattern of M.persicae in Broccoli.The results showed that the M.persicaewas aggregated in Broccoli field,the theoretial sampling number and sequential sampling model were inferred from spatial pattern paramaters,in addition,the peak of M.persicae population occurred in mid-late August to mid-September.2.Laboratory insecticides screening and field efficacy evaluation against M.persicaeThe toxicity bioassay and field efficacy tests by dipping method and spraying.The laboratory toxicity test results showed that the LC50 of flupyradifurone had the highset toxicity,was 7.67 mg·L-1 at 48 h.The LC50 of Ambda-cyhalothrin showed the lowest toxicity,was 1011.03 mg·L-1 at 48 h.The order of the toxicity of the insecticides from high to low were as follows:flupyradifurone,sulfoxaflor,abamectin,ciprofloxacin,thiamethoxam,chlorfenapyr,veratrine,imidacloprid,emamectinbencoate,clothianidin,acetamiprid,cyantraniliprole,matrine,spirotetramat,flonicamid,tolfenpyrad,spinetoram,ambda-cyhalothrin.On this basis,five kinds of flupyradifurone,sulfoxaflor,chlorfenapyr,emamectinbencoate,thiamethoxam insecticides,were selected for field experiment,the results showed that treatment of five kinds of insecticides at different concentrations had a higher control effect against M.persicae.The field control efficacies of five kinds of insecticides were 70.10%～90.11%after seven days of application.The field control efficacies of five kinds insecticides were 56.93%～82.55%after fourteen days of application.3.Co-toxicities and field efficacy evaluation of mixed insecticides against M.persicaeIn order to screen out to the combination of insecticides complex agent with synergistic against M.persicae by toxicity bioassay and field efficacy.The results showed that abamectin with flupyradifurone,sulfoxaflor and thiamethoxam,with ratio of 1:2,1:1,1:1,respectively,showed significant synergistic effect,and the co-toxicity coefficient(CTC)was 1044.19,529.60,378.03.Fields trials showed that the control efficacy of abamectin mixed with flupyradifurone,sulfoxaflor and thiamethoxam was 90.48%,89.36%,84.36%after seven days,compared with abamectin,the control effect increased by 0.25%～6.37%.Fourteen days after treatment,the control efficacy of abamectin mixed with flupyradifurone,sulfoxaflor and thiamethoxam was maintained at 75.2 5%～85.72%.4.Synergistic effect and field efficacy evaluation of spray adjuvants mixed with insecticides against M.persicaeIn order to determine the synergistic effects of different spray adjuvants to insecticides against M.persicae,three kinds of spray adjuvants mixed with two kinds of insecticides against M.persicae by toxicity bioassay and field efficacy.The results showed that synergistic effects of three kinds of spray adjuvants mixed with two kinds of insecticides were as follows:Qiangliyuan>NanoSC108>Jijian.The LC50 of flupyradifurone and thiamethoxam was 7.67 mg·L-1 and 12.66 mg·L-1 at 48 h,respectively.Among them,the synergism ratio of flupyradifurone and thiamethoxam added of Qiangliyuan were 65.58%,58.06%,respectively,the next one is NanoSC108,the synergism ratio were 63.23%,38.15%,respectively,the synergism ratio of flupyradifurone and thiamethoxam added of Jijian were 55.02%,31.12%,respectively.Field efficacy trials showed that the control efficacy of each treatment against M.persicae in Broccoli were the highest seven days after treatment,especially,the control effects of flupyradifurone and thiamethoxam reduced by 20%mixed with Qiangliyuan were as high as 94.95%and 90.47%,respectively,compared with flupyradifurone and thiamethoxam,the control effect increased by 10.91%,16.36%,respectively.Fourteen days after treatment,the control effects of flupyradifurone and thiamethoxam reduced by 40%mixed with three kinds of spray adjuvants maintained at 57.78%～81.43%、45.46%～65.18%.5.Dissipation dynamics of insecticides reduction in BroccoliThe effects of spray adjuvants on the residues of flupyradifurone and thiamethoxam in Broccoli was studied,and the degradation rule was studied by LC-MS/MS method.The results showed that the degradation laws of flupyradifurone and thiamethoxam were consistent with the first-order kinetic degradation laws,indicating that flupyradifurone and thiamethoxam were easily degradable pesticide.Among them,the residual order of the three additives added under the condition of 20%reduction of flupyradifurone were as follows:NanoSC108>Jijian>Qiangliyuan;the residual order of the three additives added under the condition of 30%reduction of flupyradifurone were as follows:NanoSC108>Qiangliyuan>Jijian;the residual order of the three additives added under the condition of 40%reduction of flupyradifurone were as follows:Qiangliyuan>NanoSC108>Jijian.The residual order of the three additives added under the condition of 20%and 30%reduction of thiamethoxam were as follows:Qiangliyuan>Jijian>NanoSC108;the residual order of the three additives added under the condition of 40%reduction of thiamethoxam were as follows:NanoSC108>Jijian>Qiangliyuan.It was concluded that under the condition of 20%reduction of the two insecticides,the addition of Qiangliyuan and NanoSC108 had a good effect on reducing the residue of the two insecticides;under the condition of 30%reduction of the two insecticides,the addition of Jijian and NanoSC108 has a good effect on reducing the residue of the two insecticides;under the condition of 40%reduction of the two insecticides,the addition of Jijian has a good effect on reducing the residue of the two insecticides.And the half-lives of each treatment of flupyradifurone and thiamethoxam were 2.57 d～3.44 d,1.96 d～4.44 d in Broccoli,respectively.