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, organo-phosphorus and carbamate groups to IV instar larvae of the multivoltine (Pure Mysore) and bivoltine (Kalimpong A) races of the silkworm showed sequential development of neurotoxic symptoms viz., excitation, head swaying, vomiting of gastric juices and moribund state followed bv death. Organochlorine insecticides were generally fast in their action compared to the organophosphorus and carbamate insecticides. Gamma HCH and endosulfan were most toxic whereas bromophos the least among the insecticides tested. Similar toxicity was observed for both the multivoltine and bivoltine races of the silkworm.