Efficacy of seed extracts of Samadera indica Gaetrn. for the management of epilachna beetle, Henosepilachna septima (Dieke)

Abstract

Snake gourd, a vegetable commonly grown in Kerala is highly prone to the attack of epilachna beetle, Henosepilachna septima (Dieke)). There is immense scope for the utilization of botanicals for the management of insects. Niepa bark tree, Samadera indica (Gaertn.) is one such potential candidate due to the presence of the bitter principle, quassinoids. In this study, we have analyzed the efficacy of S. indica seed extracts in causing feeding deterrence and altering the biology of the pest. Lethal Doses of the extracts effective against the pest was estimated by probit-dose analysis and the LD50 values ranged from 8.10 to 22.30 mg per g body weight of the insect and LD90 values ranged from 62 to 72.40 mg per g body weight of the insect. The grubs that underwent treatment with LD90 of acetone extract consumed relatively lesser quantity of leaves at 72 HAT (0.11 g). Furthermore, there was increase in duration of grubs (14 days) and pupae (7.67 days), reduced pupal weight (1.25 g). Considering the effect on feeding deterrence, mortality and changes in biology of the pest, acetone extract is the most effective extract.