Laboratory Evaluation of Comparative Toxicity of Bacillus thuringiensis Subspecies to Larvae of Plutella xylostella and Bombyx mori

Laboratory bioassay tests on the comparative efficacy of eight Bacillus thuringiensis (B.t.) subspecies against third instar larvae of Plutella xylostella L. as well as its safety to second lnstar larvae of Bombyx mori L. revealed that B.t. subsp. kurstaki (Bactospeine) was the most toxic to larvae of P. xylostella followed by B.t. subsp. thuringiensis and B.t. subsp. kurstaki (lab culture). The B.t.t. and B.t.k. (Bactospeine) were found to be less toxic to the larvae of Bombyx mori than the other species.