title: Residue evaluation of imidacloprid, spirotetramat, and spirotetramat-enol in/on grapes (Vitis vinifera L.) and soil.
abstract: A combination of imidacloprid and spirotetramat effectively controls sucking pests on grapevines. Residues of these insecticides on grapes were evaluated after treatment with spirotetramat 12% + imidacloprid 12% (240 SC) three times at 90 and 180 g a.i. ha(-1). The samples were extracted and purified by QuEChERS method and analyzed by high-performance liquid chromatography with a photodiode array detector (imidacloprid) and gas chromatography mass spectrometry (spirotetramat and its metabolite spirotetramat-enol). Satisfactory results were obtained with ranges of 80.6-98.6% for the recovery, 3.1-10% for the relative standard deviation range, and 9.8-15.6% for the uncertainty. The limits of detection and quantification were 0.015 μg mL(-1) and 0.05 mg kg(-1), respectively. Initial residue concentrations of imidacloprid after the 90 and 180 g a.i. ha(-1) treatments were 0.912 (half-life 11 days) and 1.681 mg kg(-1) (half-life 12.4 days), respectively. For spirotetramat + spirotetramat-enol, the residue concentrations were 1.337 (half-life 5.6 days) and 2.0 mg kg(-1) (half-life 7.6 days) for the 90 and 180 g a.i. ha(-1) treatments, respectively. Spirotetramat degraded faster than spirotetramat-enol. After treatment at 90 g a.i. ha(-1), the initial residues of both insecticides were within European Union maximum residue limits and a 1-day pre-harvest interval (PHI) was adequate for safe consumption of grapes. After treatment at 180 g a.i. ha(-1), the required PHI was 7 day. Therefore, a PHI of 7 day should be used after treatment with imidacloprid and spirotetramat.
authors.affiliation: Pesticide Residue Laboratory, Indian Institute of Horticultural Research, Hessaraghatta Lake P.O, Bangalore, 560089, India. soudamini_mohapatra@rediffmail.com.
authors.forename: Soudamini
authors.initials: S
authors.lastname: Mohapatra
authors.affiliation: Division of Fruit Crops, Indian Institute of Horticultural Research, Hessaraghatta Lake P.O, Bangalore, 560089, India.
authors.forename: Sampath
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Division of Fruit Crops, Indian Institute of Horticultural Research, Hessaraghatta Lake P.O, Bangalore, 560089, India.
authors.forename: G S
authors.initials: GS
authors.lastname: Prakash
mesh_terms: D001372:Aza Compounds / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004784:Environmental Monitoring / Q000379:methods*; D006207:Half-Life; D007093:Imidazoles / Q000032:analysis*; D007306:Insecticides / Q000032:analysis*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000032:analysis*; D010573:Pesticide Residues / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*; D013141:Spiro Compounds / Q000032:analysis*; D027843:Vitis / Q000737:chemistry*
chemical_list: D001372:Aza Compounds; D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010573:Pesticide Residues; D012989:Soil Pollutants; D013141:Spiro Compounds; C082359:imidacloprid; C570705:spirotetramat
keywords: Grape; Imidacloprid; Pre-harvest interval (PHI); Spirotetramat; Spirotetramat-enol