Efficacy of selected insecticides against coconut black headed caterpillar, Opisina arenosella (Walker) under laboratory and field conditions

The study was aimed at identifying alternative to monocrotophos, the only chemical recommended for root feeding against which the Opisina arenosella has shown resistance. This experiment was carried out in laboratory as well as in field conditions. In laboratory condition, among the tested chemicals viz., monocrotophos 36% SL, neemazal 1% and emamectin benzoate 5% SG gave one hundred per cent reduction followed by bifenthrin 10% EC (98.35%) and imidocloprid 17.8% SL (98.35%) as compared to untreated control. Field evaluation of selected chemicals indicated that monocrotophos 36% SL and neemazal 1%, gave one hundred per cent reduction followed by emamectin benzoate 5% SG (97.83%) and imidocloprid 17.8% SL (97.04%) as compared to untreated control. Thus besides monocrotophos other chemicals such as neemazal, emamectin benzoate, bifenthrin and imidacloprid also recorded significant mortality of coconut black headed caterpillar. The coconut palm successfully absorbed all these chemicals and can be used for root feeding.