Residue dynamics of spirotetramat and imidacloprid in/on mango and soil.

Spirotetramat is a unique insecticide having both phloem and xylem mobility and imidacloprid, a neonicotinoid insecticide, is one of the most widely used in the world. The combination formulation is very effective against sucking pests of mango. Residue dynamics of spirotetramat and imidacloprid in/on mango and soil was studied following application of the combination formulation, spirotetramat 12% + imidacloprid 12% (240 SC) at 90 and 180 g a.i. ha(-1). Spirotetramat residues in/on mango fruits were 0.327 and 0.483 mg kg(-1) after giving 3 applications at 90 and 180 g a.i. ha(-1), respectively. The residues remained on mango fruits for 7 days and dissipated with the half-life of 3.3 and 5.2 days, respectively. Residues of spirotetramat-enol, the major metabolite of spirotetramat in plant, were not detected in mango fruits. Initial residues of imidacloprid on mango fruits from the two treatments were 0.329 and 0.536 mg kg(-1), respectively. Imidacloprid residues remained on mango fruits beyond 15 days and dissipated with the half-life of 5.2 and 8.2 days. The residues of spirotetramat, spirotetramat-enol and imidacloprid were found below quantifiable limit of 0.05 mg kg(-1) in mature mango fruits and field soil at harvest.