Acute toxicity of insecticides to the multivoltine and bivoltine races of the silkworm, Bombyx mori L.

Topical application of graded doses of 12 insecticides belonging to the organochlorine, organophosphorus and carbamate groups to 4th-instar larvae of multivoltine (Pure Mysore) and bivoltine (Kalimpong A) races of Bombyx mori showed sequential development of neurotoxic symptoms (excitation, head swaying, vomiting of gastric juices and a moribund state) followed by death. Organochlorine insecticides were generally rapid in their action compared to the organophosphorus and carbamate insecticides. Gamma-HCH [lindane] and endosulfan were the most toxic, and bromophos the least, among the insecticides tested. Similar toxicity was observed in the multivoltine and bivoltine races.