Study On The Residue And Metabolism Of Lambda-Cyhalothrin On Pakchoi

As a pyrethroid insecticide with wide insecticidal range,strong activity,fast efficacy and low toxicity,Lambda-cyhalothrin is widely used in vegetables,fruit trees and other crops on cabbage caterpillars and diamondback moths.,Aphids and other pests.However,due to the phenomenon of unreasonable and unscientific use of the pesticide,the risk of excessive pesticide residues in crops has also increased correspondingly,which has harmed human health and safety and the safety of the ecological environment.Therefore,studying the deposition,distribution,digestion and metabolism of lambda-cyhalothrin on crops is of great significance to the scientific reduction of the use of this pesticide.In this thesis,the pakchoi"Shanghai Green",which is used more lambda-cyhalothrin,was selected as the test object,and the deposition,distribution and digestion and metabolism of lambda-cyhalothrin on pakchoi were studied.The main results of the experiment are as follows:1.0.5 times（0.5X）,0.75 times（0.75X）,1 times（1X）,1.5 times（1.5X）,2 times（2X）the recommended dosage（5.625 g ai/hm2）of the recommended dosage,high-efficiency chlorofluoro The distribution of initial deposits of fenpropathrin in different parts of pakchoi tended to be consistent.Under different application dosages,the initial deposition concentration of lambda-cyhalothrin on pakchoi showed as follows:2X>1.5X>1X>0.75X>0.5X,rosette stage>adult plant stage.Among them,the leaf and whole plant of pakchoi had no significant difference under the application dose of0.75X and 1X（P>0.05）,and the petiole of pakchoi had no significant difference under the application dose of 0.5X and 0.75X（P>0.05）.The initial deposition concentration of lambda-cyhalothrin on different parts is as follows:leaf>whole plant>petiole>planting soil>root.2.In Sanya,Hainan and Hefei,Anhui,1.5 times the recommended dose of lambda-cyhalothrin（8.44 g ai/hm²）was applied to pakchoi,the digestion rate of lambda-cyhalothrin in different parts of pakchoi was as high as Sanya,Hainan>Hefei,Anhui,the half-lives are 1.8～2.4 d in Hainan and 3.7～4.7 d in Hefei.3.Under different planting environment models,the degradation rate of lambda-cyhalothrin(5.625 g ai/hm²)at the recommended dose of 1 times the recommended dose of pakchoi leaves,whole plants and petioles is open field>greenhouse>open field shading,and the half-lives are 1.7～3.9 d,2.9～6.2 d,4.5～9.0 d.In the soil and roots of pakchoi,the degradation rate of lambda-cyhalothrin is open field shading>greenhouse>open field,and the half-lives are 7.0-7.4 d,7.1-8.7 d,and 9.0-9.8 d,respectively.4.In different growth periods of pakchoi,the recommended dose of lambda-cyhalothrin(5.625 g ai/hm²)is applied.and the degradation rate of pakchoi’s leaves,whole plant and petiole in the two different growth periods are all the open field>greenhouse>the open Shading,the digestion half-life is rosette stage<adult plant stage.The half-life of different parts of pakchoi in the rosette stage are 3.9-6.0 d in the open field,5.3-7.9 d in the greenhouse,and 8.1-9.9 d in the open field shading,the half-life of the different parts of the pakchoi in the adult plant stage is 5.9～7.5 d in the open field,7.3～9.6 d in the greenhouse,and11.0～13.3 d in the open field shading.5.The metabolites of lambda-cyhalothrin on pakchoi were determined by GC-MS/MS.The metabolites of lambda-cyhalothrin on pakchoi were 3-phenoxybenzaldehyde（PBCHO）.