Persistence and Dissipation of Dichlorvos and Profenofos on Mulberry Leaves

Abstract

Persistence and dissipation properties of dichlorvos and profenofos in/on mulberry leaves were studied. Dichlorvos (76 WSC) and profenophos (50 EC) were sprayed at recommended dose (2 mL/L) and double the dose (4 mL/L) and leaf samples were drawn at different intervals in triplicate and residues derived from the QuEChERS method were quantified on gas chromatography-electron capture detector (GC-ECD). The initial deposits of dichlorvos and profenofos were between 1.18 to 2.79 and 2.19 to 4.72 μg g-1 in the recommended and double the dose, respectively. Dichlorvos dissipated to 0.03 (98.8%) and 0.031 μg g-1 (97.38%) in recommended and double the doses, respectively three days after spray. Residues of profenofos dissipated to the extent of 95.8% and 94.30%, respectively, at recommended and double doses in 15 days. Dissipation pattern followed first order kinetics for both the insecticides with half life periods of 0.52 and 4.29 days for dichlorvos and profenophos, respectively. Present studies suggest that the use of dichlorvos and profenofos at the recommended doses does not pose any hazard to silkworm, if waiting periods of 2.89 and 32 days respectively,were observed before harvesting mulberry leaves to feed silkworms.