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.
