Persistence behavior of imidacloprid and carbosulfan in mango (Mangifera indica L.)

Imidacloprid was sprayed on mango cv. Dashehari at 0.3 mL L(-1) of water during pre-bloom stage with 6-8 cm panicle size (first week of March) to control hopper and carbosulfan was sprayed at 2.0 mL L(-1) of water in the trees of mango hybrid (H-1000) during fruit development stage (first week of May) to control leaf webber. Residues of both the insecticides were analysed in peel, pulp and fruit at different stages of fruit development and maturity. The initial residues of imidacloprid, after 30 days of spraying, were 1.21, 0.56 and 1.77 mg kg(-1) in peel, pulp and whole fruit, respectively. The residues persisted in peel for 60 days and in pulp for 50 days and dissipated with a half-life of 38 days. Mature Dashehari fruits at harvest (after 85 days of spraying) were free from imidacloprid residues. Carbosulfan in mango peel dissipated from 5.30 mg kg(-1) (after 1 h of spraying) to 0.05 mg kg(-1) at the time of harvest (after 45 days of spraying). Carbosulfan residue in pulp was very low (0.08 mg kg(-1)) after 1 h of spraying, which increased gradually to 0.90 mg kg(-1) after 10 days and finally came down to 0.04 mg kg(-1) after 26 days of spraying. The insecticide residue was not detected in the pulp at the time of harvest. The residues persisted in pulp for 26 days and in peel for 45 days and degraded with a half-life of 7 days. The dissipation of both imidacloprid and carbosulfan followed first order rate kinetics in whole fruit (peel + pulp). Therefore, the safe pre-harvest intervals were suggested to be 55 days for imidacloprid and 46 days for carbosulfan before consumption of mango fruits after spraying of these insecticides.