Transport And Metabolism Of Three Pesticides In The Peach Trees

There are three ways of applying pesticides:broadcast, bagging fruit before spraying and root-irrigation with pesticide. Accumulation and transport of acephate (ACE), carbendazim (MBC) and beta-cypermethrin (Bcy) on peach were studied by demonstrating the parents and their metabolites which were affected by applying these pesticides in three different ways. This paper compared the inabsorbabilities of ACE, MBC and Bcy through demonstrating the residues of pesticides and metabolites in different intervals, and evaluated the risks of residues on peaches affected by applying in different ways. The main results are as follows:1、establishment of residue detectionEach of the pesticides and metabolites except Bcy was extracted acetonitrile from peach samples. Concentrated the extracting solution and diluted the condensate with mobile phase to specific volume. Samples were detected by UPLC/MS/MS after filtration with disposable filter membrane. The adding recovery rates of ACE, MAP, MBC,2-AB and BEN detected by this method were in the ranges of 82.1%～93.1%,101.4%～110.9 %,97.8%～110.5%,72.13%～96.53%,79.3%～98.9%respectively, and the relative standard deviations of each were 1.2%～3.1%,0.3%～2.7%,0.6%～4.1%,1.0%～1.5% and 0.7%～4.2%separately, in the adding concentrations from 5 to 500μg/kg. The Bcy residue were extracted by acetonitrile and diluted by n-hexane in certain volume. The samples were detected by GC-ECD. The adding recovery rates of Bcy were in the range of 76.2%～82.3%, the relative standard deviations were in the range of 0.6%～2.4%, in the adding concentrations from 5 to 500μg/kg. The accuracies and precisions of methods met the request of pesticide residue analysis.2、Accumulation, transport and metabolism of three pesticides in peachesThe dynamic curves of degradation of three pesticides which were applied by broadcast on peaches accord with the first order kinetic model. Because that the absorption of pesticide was not steady and the adsorbing capacity was not saturated, after applying two hours later, the peaks of accumulation of ACE applied in high and low concentration, MBC applied in low concentration, Bcy applied in high concentration did not show in two hours but in one day. The data of the experiments of bagging fruit before spraying and root-irrigation with pesticide suggest that the three pesticides can absorb by leaves and roots and then accumulate, transform and metabolize in plants. The amount of all residues of the two experiments were rising at first and then decreasing along with the time passed. And the peak of them showed after one to three days.3 Compare of three pesticides’inabsorbabilitiesACE and MBC are systemic pesticides with strong absorption. While Bcy is not a systemic pesticide and Bcy doesn’t have strong ability of absorption. Residues of ACE, MBC and Bcy of test groups of bagging fruit before spraying and root-irrigation with pesticide were demonstrated. Each of their maximum value of accumulation was 612.45、 316.66、216.88 (μg/kg) in group of bagging fruit before spraying and 237.98、171.01、 26.35 (μg/kg) in group of root-irrigation with pesticide, separately. These data suggest that ACE and MBC have stronger ability of absorption than Bcy. And on another side, after 7 days Bcy cannot be detected in two groups, but ACE and MBC still can be detected after 15 days. It also indicated that the absorption of Bcy was weaker.4 Risk assessments of residues of ACE, MBC and Bcy on peachesResidues of all the pesticides applying in different ways can be detected. But the degradation rates were above 90% and all the residues were less than MRL after 15 days. Risks of applying with recommended dose are low if we don’t consider of the presence of metabolites. The residue of broadcast was 10 to 30 times higher than bagging fruit before spraying and root-irrigation with pesticide. So we can choose appropriate ways to apply these three pesticides. Metabolites of ACE and MBC were detected in samples. The maximum of MAP, the metabolite of ACE, was 140μg/kg. In consideration that Methamidophos is forbidden on fruiters and 2-aminobenzimidazole has negative effects on human, decrease the use on fruiters is suggested.