Residue study of imidacloprid in grapes (Vitis vinifera L.) and soil

Abstract

Introduction Grape, an important fruit crop of India, is affected by thrips that is a destructive sucking insect of grapevine. Imidacloprid, a neonicotinoid insecticide, gives very good control of this insect. Objectives Study of the residue persistence of imidacloprid on grapes, to estimate its residue deposit, half-life of degradation, safe pre-harvest interval and harvest time residues for consumption of this fruit after its multiple applications. Methods Extraction with acetonitrile, partitioning into dichloromethane, clean up with neutral alumina and estimation of residues with high-pressure liquid chromatography, using a UV-VIS detector at wavelength of 270 nm. Results Initial residue deposit of imidacloprid on grape berries following treatment of Confidor 200 SL at the recommended and double the recommended dose of 80 and 160 g a.i. ha1 were 0.74 and 1.26 mg kg1, respectively. Residues remained in the fruits up to 60 days but at a low level of 0.056 and0.108 mg kg1. The residues dissipated with the half-life of 16.6 days from both the treatments. Conclusion The pre-harvest interval recommended for safe consumption of grape berries is 60 days. Residues of imidacloprid in grape berries and soil at harvest (105 days after the last treatment) were observed to be below detectable limit of 0.05 mg kg1 from both the treatments.