Evaluation of different solvent extracts of sweet flag rhizome, Acorus calamus (L.) on pulse beetle, Callosobruchus maculatus (F.)

Abstract

Investigation was conducted to test the insecticidal activity of sweet flag rhizome (Acorus calamus L.) extracts on Callosobruchus maculatus (F.) on cow pea in storage during 2016-2017 at the Department of Agricultural Entomology, Agricultural College and Research Institute, Coimbatore. Sweet flag (SF) extracts obtained by different extraction methods (soxhlet and mechanical shaker extraction) using various solvents viz., hexane, ethyl acetate and ethanol exhibited varied levels of insecticidal action on Callosobruchus maculatus (F.). Pulse beetle on cow pea seeds, there was a positive correlation between the concentration of the sweet flag extracts and the insecticidal action. The LC50 value of hexane, ethyl acetate and ethanol extract of SF obtained in soxhlet extraction for C. maculatus was 0.042, 0.230 and 0.069 per cent at 48 hours, respectively. The LC50 value of hexane, ethyl acetate and ethanol extract of SF obtained in mechanical shaker extraction for C. maculatus was 0.009, 0.275 and 0.069 per cent at 48 hours, respectively. Hexane extract of SF obtained from both extraction methods (soxhlet and mechanical shaker) showed cent per cent mortality at 0.09 and 0.1 per cent on 5th day after treatment (DAT). For ethyl acetate and ethanol extracts of SF obtained from both extraction methods (soxhlet and mechanical shaker), caused more than 80 per cent mortality was observed on 6th DAT at 0.09 and 0.1 per cent on pulse beetle respectively. On 90 DAT, hexane extract of SF obtained from both extraction methods and of ethyl acetate extract of SF obtained from mechanical shaker extraction, there was no progeny development of C. maculatus at 0.05, 0.07, 0.09 and 0.1per cent concentrations. Cent per cent mortality and there is no progeny development C. maculatus in 0.09 and 0.1 per cent of hexane extract of SF (both extraction methods) and ethyl acetate extract of SF (mechanical shaker extraction) treated cowpea seeds upto 90 days when compared to untreated control.