Annals of Plant Protection Sciences

The persistent toxicity of five formulations, of which two from Bacillus thuringiensis vaL kurstaki (halt-55000 SU. mg⁻¹ and biolep-32000 1U. mg⁻¹), one each of avermectin-1.8% w/v (vertimec) and Beauvaria bassialla 1 x 10⁷ spore mil (bassina) and a conventional pesticide malathion-50EC@ 0.1%, 0.2% and 0.05%, respectively was evaluated against 3rd instar larvae of Pieris brassicae on cauliflower. Avermectin, a microbial toxin was found to be most effective biopesticide followed by malathion, halt and biolep. The respective PT values were 240.8, 238.7, 177.1 and 109.9 whereas LTvalues were 2.55, 2.49, 1.89 and 0.92. The order of relative so efficacy based on PT and LT₅₀ was remained the same.