Division of Entomology, Indian Agricultural Research Institute, New Delhi - 110012, (India).
1Department of Entomology, CCS Haryana Agricultural University, Hisar, Haryana, (India).
The persistence and residual toxicity of laboratory prepared emulsions of synthetic pyrethroids along with their proprietary formulations was evaluated against 9±1-day old larvae of Spodoptera litura (Fab.) fed on treated castor and cabbage. In the case of castor crop, considering the LT50 and PT values, decamethrin + toluene + Triton X-100 exhibited maximum residual toxicity, being 19.638 days, followed by proprietary decamethrin (17.750 days). The LT50 values for formulated cypermethrin, fenpropathrin and fenvalerate were 15.588, 13.234 and 11.959 days in comparison to their corresponding proprietary products, i.e., 16.328, 16.368 and 17.640 days, respectively. In the case of cabbage, proprietary fenpropathrin registered maximum residual toxicity, being 23.703 days followed by decamethrin + toluene + Triton X-100: (20.450 days). The descending order of residual toxicity in the case of cabbage was: fenpropathrin proprietary, 23.703 days; decamethxin + toluene + Triton X-100, 20.450 days; decamethrin proprietary, 20.174 days; cypermethrin + xylene + Triton X-100, 19.129 days; fenvalerate proprietary, 18.928 days; fenvalerate + C-IX + tween-80, 17.811 days; cypermethrin proprietary, 17.652 days; and decamethrin + toluene + Triton X-100, 16.854 days.
