Knockdown Toxicity of Insecticides and B.T. Formulations on Larvae of Teak Defoliator, Hyblaea puera

Laboratory experiments were conducted for assessing the knockdown toxicity of various insecticides and B.t. formulations against third and fourth instar larvae of Hyblaea puera. The results indicated that the mortality of third instar larvae was 85-100 per cent in all insecticides and B. t. formulations within 2 hours of feeding. A new insecticide, Nurelle D 505 at 0.082% and 0.11%. Monocrotophos 0.05%, Quinalphos 0.05% and the B. t. formulations Delfin @ 159 IU/ml were found to cause cent per cent knockdown toxicity within 8 hours after inoculation against fourth instar larvae of H. puera. However, all the 24 HAI. The B. t. formulations were effective even at lower concentrations against third instar and at higher concentrations against fourth instar.