title: Dissipation kinetics and effect of different decontamination techniques on the residues of emamectin benzoate and spinosad in cowpea pods.
abstract: Dissipation and decontamination of the semisynthetic macrolide emamectin benzoate and the natural insecticide spinosad on cowpea pods were studied following field application at single and double doses of 11.0 and 22 and 73 and 146 g ai ha(-1), respectively. Residues of these naturalytes were estimated using LC-MS/MS. The initial deposit of 0.073 and 0.153 mg kg(-1) of emamectin benzoate dissipated below quantitation level on the fifth and seventh day at single and double dosage, respectively. For spinosad, the initial deposits of 0.94 and 1.90 mg kg(-1) reached below quantitation level on the 7th day and 15th day at single and double dosage, respectively. The half-life of emamectin benzoate and spinosad was 1.13-1.49 and 1.05-1.39 days with the calculated safe waiting period of 2.99-6.12 and 1.09-3.25 days, respectively, for single and double dosage. Processing of the harvestable pods with different decontamination techniques resulted in 33.82 to 100 % removal 2 h after the application of emamectin benzoate and 100 % removal 3 days after spraying, while the removal was 42.05 to 87.46 % 2 h after the application of spinosad and 38.05 to 68.08 % 3 days after application.
authors.affiliation: Department of Agricultural Entomology, College of Agriculture, Kerala Agricultural University, Vellayani P.O., Thiruvanthapuram District, Kerala, 695522, India, vsree_ag@yahoo.co.in.
authors.forename: V
authors.initials: V
authors.lastname: Vijayasree
authors.forename: Hebsy
authors.initials: H
authors.lastname: Bai
authors.forename: Thomas Biju
authors.initials: TB
authors.lastname: Mathew
authors.forename: Thomas
authors.initials: T
authors.lastname: George
authors.forename: George
authors.initials: G
authors.lastname: Xavier
authors.forename: N Pratheesh
authors.initials: NP
authors.lastname: Kumar
authors.forename: S
authors.initials: S
authors.lastname: Visalkumar
mesh_terms: D002853:Chromatography, Liquid; D003666:Decontamination / Q000379:methods; D004338:Drug Combinations; D004784:Environmental Monitoring; D006207:Half-Life; D007306:Insecticides / Q000032:analysis*; D007559:Ivermectin / Q000031:analogs & derivatives* / Q000032:analysis; D007700:Kinetics; D018942:Macrolides / Q000032:analysis*; D013058:Mass Spectrometry; D010573:Pesticide Residues / Q000032:analysis*; D053719:Tandem Mass Spectrometry
chemical_list: D004338:Drug Combinations; D007306:Insecticides; D018942:Macrolides; D010573:Pesticide Residues; D007559:Ivermectin; C108024:emamectin benzoate; C415329:spinosad