| In recent decades,neonicotinoid insecticides have developed in the global pesticides market,and it was also the fastest growing class of pesticides and has become the world’s largest botanical insecticides and imidacloprid represented by the neonicotinoid insecticide is the first sales of all pesticides varieties.New neonicotinoid insecticides have been widely concerned at home and abroad because of its effectiveness,selectiveness and it is low-toxic to human being and mammal and no mutually resistance with other insecticides.The domestic and foreign pesticide companies carry out the related research on the analogues.Besides the imidacloprid,several kinds of new neonicotinoid insecticides have been developed.Imidaclothiz is a new kind of insecticide developed in recent years.The secon-d generation of the new neonicotinoid insecticides developed by Nantong Jiangshan Agrochemical&Chemical Co.Ltd.Its chemical name is（1-（2-chloros-5-thiazolylm ethl）-N-nitroimida-zolin-2-ylideneamine）.Imidaclothiz is active against numerous suck ing and biting insects,including aphids,whiteflies,beetles and some Lepidoptera sp ecies as well.Neonicotinoid is a kind of internal absorption pesticide and to use in tea will be absorbed by tea trees,transport and metabolism.Little information is available about degradation mechanism secondary metabolite residues,toxicity since the metabolites in environment was in trace and its were difficult to be detect.Therefore,imidaclothiz as the research object in this experiment,combined with plant tissue culture technology,and through the induction of tea callus,callus culture to expand suspension culture was established the platform about metabolic mechanism and screening of secondary metabolites,and to further study the other cultivars about degradation mechanism.The main conclusions obtained were listed as follows:1.Based on previous experiments,leaves of Longjing 43 steril strain was selected as the explants for tissue culture and the callus induction conditions were optimized in autumn and winter.The conclusion showed that the best induction condition of primary callus was:using MS（Murashige&Skoog,1962）medium with plant growth regulator 2,4-D 2.0 mg·L-1+KT 0.5 mg·L-1+6-BA 0.5 mg·L-1;p H5.8;the induction time is 30 days.Callus keep loosen texture and white color with high growth rate.It suitable for liquid suspension culture2.The suspension culture conditions of callus of Longjing 43 leaves were optimized.Based on B5 medium with plant growth regulator 2,4-D 1.0 mg·L-1+KT0.1 mg·L-1,liquid loading 40m L/150m L,and weigh about 3 g callus and used sterile blade cut into the medium,the temperature of liquid culture condition is 25℃±1 and Constant Temperature Shaking Incubator speed is 120 r·min-1,under dark condition for culturing.After 7 to 10 days of culturing.To select primary suspension about 20m L poured into aseptic fresh liquid medium with B5+2,4-D 1.0 mg·L-1+KT 0.1 mg·L-1（20m L/150m L）as secondary culture,and poured 20 m L suspension culture liquid into the rest of the primary suspension.Continuous culture for 21-28 days,the suspension cells of tea plant could be isolated after 3-4 times subculture.The suspension cells keep highly growth rate and highly metabolic activity.The suspension system is stable and it is suitable for studying on pesticide metabolites.3.Dynamic simulation of degradation of imidaclothiz in the field.Selected the same growth of the soil tea plant with the addition of 10μg imidaclothiz standard,10%wettable powder,respectively.Picked the leaves in 0 d,1 d,3 d,5 d,7 d,10 d,14 d and test by UPLC-MS/MS.The results show that the leaves begen to absorb imidaclothiz standard about 0.044μg and 10%wettable powder about 0.057μg in 0 day;and the leaves absorbed imidaclothiz standard 0.212μg and wettable powder 0.347μg on 14days.The absorption rate of the standard was 2.12%and degradation rate was 62.58%;the absorption rate of wettable powder was 3.47%and degradation rate was 57.20%.its prove that the absorption rate of wettable powder is higher than that of standard and tea leaves were absorbed imidaclothiz after application on 0 day.it is concluded that the wettable powder has auxiliary agent,which is beneficial to the passage of the imidaclothiz through the wax layer of leaves and promoting the absorption of the leaves.4.Research on the imidaclothiz metabolism of tea plant suspension cells.vigorous growth of tea suspension cells was selected as materials and addition 400μL of 500μg·m L-1imidaclothiz standard.The sampling interval was 5 days and keep sampling for 75 days,each sample was extracted 1m L and detection by HPLC.The degradation trend of the imidaclothiz in suspension cells was obtained.The results showed that cells did not produce significant degradation effect in imidaclothiz and the degradation rate was only about 2%;we found the mass to charge ratio of 198 and 216 of imidaclothiz suspected metabolites after preliminary detection of samples.5.Research on the metabolism of several new neonicotinoid insecticides in tea suspension cells.vigorous growth of tea suspension cells was selected as materials and draw 400 u L from 500μg·m L-1to acetamiprid,thiamethoxam standard and addition into suspension cells,respectively.The sampling interval was 5 days and keep sampling for 75 days,then each sample was extracted 1m L and detection by HPLC.Results showed that the degradation rate of thiamethoxam was 54.24%and cells have no significant degradation effect in acetamiprid... |
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