Control Efficiency Of Potato Seed-coating With Thiamethoxam On Aphids And Virus Disease And Effect Of Seed-coating On Feeding Behaviour Of Myzus Persicae In Potato Plant

Potato(Solanum tuberosum L.) is the fourth food crop in the world, aphids and virus diseases is important plant diseases and insect pests,plant growth and development was bad,yield and quality decreased,variety degeneration and many other issues.The experiment of toxicity test of thiamethoxam on Myzus persicae was determined,To construct the 1.2% thiamethoxam flowable concentrates for seed coating of formulation was developed,The control effects and efficacy duration of potato seeds coated with 1.2% thiamethoxam seed coating on aphids and virus disease,and the safety of natural enemy insects were investigated in the field.The dynamic of residue in potato plants and tuber were detected using high performance liquid chromatography(HPLC).The comparison research on the feeding behavior of Myzus persicae in thiamethoxam coating,dressing and blank on the potato seedling was conducted by electrical penetration graph technology(EPG).To lay the foundation for the promotion of potato seed coating, reducing the economic loss caused by the damage of aphids and virus disease,the main research results are as follows:1.The experiment of toxicity test of thiamethoxam and imidacloprid on Myzus persicae was conducted.The results showed that the LC50 of two reagents including imidacloprid and thiamethoxam were: 165.5464mg/l、45.4228mg/l.The virulence of thiamethoxam was higher than imidacloprid,and the relative toxicity was 3.6446. There were significant differences between imidacloprid and thiamethoxam,the activity of thiamethoxam was betterr than imidacloprid.2.To construct the 1.2% thiamethoxam flowable concentrates for seed coating of formulation,a series of effective composition content,wetting agent,dispersing agent,film-forming agent and other agents were screened by flow point method.The 1.2% thiamethoxam flowable concentrates for seed coating which contains: thiamethoxam 1.2% as active ingredient,filler 3%,and promoter1 3.3%,promoter2 1.8%,dispersing 1.5%,dyes 5.0%,film-forming agent 8.0%,suspending agent 2.8%,antifreezing agent 3.0%.Its quality index and effect on the the emergence rate were determined.The results showed that the above formulation had good film-forming,high suspension rate,perfect heat storage stability.The further field emergence experiment revealed that,when effective dose was 1:80 coating,the 1.2% thiamethoxam flowable concentrates for seed coating had a little effect on the emergence rat,1:100 and 1:120 had no effect.These results demonstrated applying in the field was feasible.3.The virus disease of potato is an important disease and it could be prevented by controlling of aphids.The control effects and efficacy duration of potato seeds coated with 1.2% thiamethoxam seed coating on aphids and virus disease,and the safety of natural enemy insects were investigated in the field.The results showed that the aphid number and disease index of virus disease were lower in the plants of seed coating treatment than those of control.During aphids occurrence peak for the first time,the control effects on aphids more than 80.00% and the control effects on virus disease were 100.00%.During aphids occurrence peak for the second time,the control effects on aphids were 76.92% and the control effects on virus disease were 79.67%.So the efficacy duration was as long as 120 d,which can realize a single pesticide application to reduce the aphids,control the effect of virus disease. And there were toxicity to chrysopids and ladybug.4.The dynamic of residue in potato plants and tuber were detected using high performance liquid chromatography(HPLC).The kind of virus disease in potato tuber were detected using Double Antibody Sandwieh Enzyme-linked inununosorbant assay(DAS-ELISA).The residue dynamic of thiamethoxam residue in potato plants was accorded with the first-order dynamic equation C=37.639e-0.0559 t,r=-0.9879,based on the thiamethoxam residue 33.975 mg/kg at the 60 th day after planting,and the half-life period was12.4d.The period of the longer residual effect of thiamethoxam in potato plants.Meantime,Potato tubers from plangting to harvest,were not detected thiamethoxam in potato tubers,that through root absorption tothe transmission.The PVY virus did not detected in tubers,the coating effectively control number of occurrence of aphids,which can effectively inhibit the spread of the PVY virus.5. In order to studing effect of thiamethoxam coating on feeding behaviour of Myzus persicae in potato plant,the comparison research on the feeding behavior of Myzus persicae in thiamethoxam coating,dressing and blank on the potato seedling was conducted by electrical penetration graph technology(EPG).The results showed that: The frequency of np wave,C wave and stylet in intercellular penetration increased,and the number of E1 wave and E2 wave reduced.It’s the first time appeared the period of E1 wave significantly prolonged and the duration of the E1 wave shortened.The conclusion was:there were some factors in thiamethoxam coating potato seedlings hinder Myzus persicae feeding,so that the number of Myzus persicae feeding reduced,the feeding time delayed, the feeding amount reduced.