Toxicity of newer insecticides to the coconut caterpillar Nephantis Serinopa Meyr and its parasite Bracon Brevicornis Wesmeal

Abstract

The LD 50 levels of toxicity of phosalone, endosulfan, malathion, quinalphos, fenthion, phosphamidon. monocrotophos, fenitrothion, dichlorvos, BHC and carbaryl to 4th instar larvae of the coconut caterpillar Nephantis seringa were 0.02428, 0,02925, 0.05288, 0.05614, 0.08416, 0.09477, 0.09833, 01013, 0.1639, 0.2920and 0.4990 respectrvely. Toxicity of residues of dichlorvos 0.05%, fenitrothion, 0.05%, malathion 0.05% on coconut leaves to 1st instar larvae of N. serhwpa had become negligible on the 8th day of their application and that of residues of quinaiphos 0.05%, phoslone 0.05% and BHC 0.2% on the 16th day of application; residues of carbaryl 0.2%, and monocrotophos 0.02% showed toxicity beyond 16 days. Toxicity of residues of the same concentrations of dichlorvos, fenitrothion, fenthion, endosulfan and phosphamidon on coconut leaves to adults of Bracon brevicomis had become negligible in 8 days of application and that of residues of malathion, quinaiphos, phosalone and BHC in 16 days of application; residues of monocrotophos and crabaryl remained toxic to parasites beyond 16 days.