RESIDUAL TOXICITY OF INSECTICIDES ON CABBAGE CATERPILLAR (PIERIS-BRASSICAE) AND THEIR DISSIPATION ON CAULIFLOWER (BRASSICA-OLERACEA CONVAR BOTRYTIS VAR BOTRYTIS)

An experiment was conducted during winter season (rabi) of 1988- 89 to study the effect of residual toxicity of insecticides on cabbage caterpillar [Pieris brassicae (L.)], and their dissipation on curd of cauliflower [Brassica oleracea L. convar botrytis (L.) Alef. var botrytis L.]. The order of toxicity of insecticides within 24 hr of spray was decamethrin > dichlorvos > endosulfan > permethrin > cypermethrin > fenvalerate > monocrotophos >malathion. A day after the spray the order was: decamethrin > permethrin > endosulfan > cypermethrin > monocrotophos > malathion. Dichlorvos killed the second-instar larvae of the cabbage caterpillar within 5 days; decamethrin, permethrin, fenvalerate, cypermethrin, malathion within 7 days; endosulfan within 10 days and monocrotophos within 15 days after the spray. The initial deposits of 14.87, 4.14, 11.11, 3.88, 46.96,27.13, 22.0 and 28.27 ppm respectively of cypermethrin, decamethrin, fenvalerate permethrin, dichlorvos, malathion, monocrotophos and endosulfan reached below the maximum residue limit in 7.26, 6.55, 7.4, 6.4, 5.33, 6.35, 12.29 and 11.59 days.