Toxicity of field-Weathered residues of insecticides to the cabbage butterfly Pieris brassicae L.

Abstract

In biological and chemical assessments of insecticide residues on cauliflower (Brassica oleracca varbotrytis or 'Snowball'),quinalphos and malathion dissipated quickly, followed by fenitrothion ' while esdosulfan and phosalone were relatively persistent. Minimum effective level of quinalphos for thedenote  larvae was 34.4 to 36.0 times less than its initial deposit on leaves followed by fenitrothion(14.7 to l5.2 times), phosalone (7.5 to 8.8 times), endosulfan (6.5 to 7.2 times) and malathion(1.4 times). Phosalone provided maximum period of protection against the larvae (17 days), whilefenitrothion, endosulfan and quinalphos for about 10 days. Malathion was not effective even forI full day (0.8 day).