套袋对芒果中甲基硫菌灵与吡虫啉农药残留的影响

用甲基硫菌灵与吡虫啉喷施套袋后的热农1号芒果,通过不同果袋处理、多次喷施农药和检测不同果实部位农药残留量3个试验研究套袋对芒果农药残留的影响及农药在果实上的残留和分布情况。采用高效液相色谱串联质谱法(UPLC-MS/MS)同时检测甲基硫菌灵、降解物多菌灵和吡虫啉,3种残留物最低检出限分别为0.5、0.12和0.5μg/kg。结果表明,不同果袋处理均能显著减少农药残留量,但白色纸袋(白袋)处理和黄色双层纸袋(黄袋)处理无显著差异。多次喷施农药时,对照(CK)果肉中3种农药总残留量在前50 d(喷药4次)持续极显著增加并超标,白袋处理在40 d(喷药3次)达到最大值并处于安全范围,果实成熟时CK和白袋处理农药残留均有所下降。不同果实部位的农药残留差异极显著,CK的外层果皮富集86.02%的甲基硫菌灵残留物和45.62%的吡虫啉,白袋处理则分别为66.93%和43.78%,但吡虫啉在白袋处理中的分布差异不显著。综上说明套袋能有效减少热农1号芒中的农药残留,甲基硫菌灵残留物主要富集果实表皮中,而吡虫啉内吸性更强,在果肉中也有大量残留,在多次喷药时,套袋能将2种农药控制在安全范围。

Effects of Fruit Bagging on Residual of Thiophanate-methyl and Imidacloprid in Mango Fruit

The ‘Renong No.1’ mango in the open fields was sprayed with thiophanate-methyl and imidacloprid to quantify the effects of bagging on pesticide residues.The following 3 methods were adopted in the experiment:different bagging treatments,excessive spraying pesticides and testing the pesticide residues in different parts of fruits.Changes in the residue levels of thiophanate-methyl and its metabolite carbendazim and imidacloprid in mango were determined by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS).The limits of quantification were 0.5,0.12 and 0.5 μ,g/kg for all the 3 fungicides respectively.Results showed that fruit bagging decreased the pesticides residues in mongo significantly,and the difference between white paper bag (WB) and yellow double bag (YB) treatments was not significant.After 50 days (sprayed 4 times),residue levels of no bagging (CK) mongo increased continuously,and WB reached the maximum after 40 days (sprayed 3 times).After 60 days (sprayed 5 times),the residue of thiophanate-methyl and its metabolite carbendazim was within safe level,imidacloprid not.The total pesticides in WB were within safe level.The residues of thiophanate-methy and its metabolite carendazim in the outer rind were 86.02％ in CK,and WB were 45.62％.The residue of midacloprid was 66.93％ and 43.78％ in CK and WB respectively.