Residue and bio-efficacy of endosulfan against pest complex of fodder cowpea

The bio-efficacy of the organochlorine insecticide endosulfan in the management of insect pest complex of cowpea vis-a-vis the occurrence of residues and its dissipation pattern has been studied. Endosulfan was applied twice after 30 and 45 days of sowing, at two doses viz. 0.07% (490 g a.i./ha, T1) and 0.14% (980 g a.i./ha, T2). At the recommended dose (0.07%) endosulfan could prevent 80–90% over all damage caused by different insect pests of cowpea. The initial residues of endosulfan in cowpea leaves were 11.12 μg/g in T1 and 26.76 μg/g in T2 after first spray whereas after second spray these were 15.67 μg/g in T1 and 31.38 μg/g in T2 which gradually dissipated with time and reached below 1 μg/g within 15 days. The dissipation pattern of endosulfan in cowpea leaves was found to follow first order kinetics. The half-life values were observed as 3 and 3.24 days, and safe waiting periods were calculated as 9 and 13 days in T1 and T2 respectively.