Evaluation of insecticidal activity of Lawsonia inermis Linn. against the red flour beetle, Triboliumcastaneum(Herbst)Author(s): KamalKrishna Biswas, Nusrat Sharmin, M.Ahasanur Rabbi
Lawsonia inermis Linn. (Lythraceae), commonly known as Henna, is a popular skin and hair coloring agent in many parts of the world. It is traditionally used as amedicinal plant by diverse groups of tribal/ethnic people. The presentwork was aimed at studying the insecticidal activity of leaf and fruit of Lawsonia inermis against the red flour beetle, Triboliumcastaneum (Herbst) which is considered as a major pest of stored grains. The leaves and fruits of Lawsonia inermis were successively extracted with ethyl acetate and methanol at room temperature to yield EAL (ethyl acetate extract of leaves), EAF (ethyl acetate extract of fruits),MEL (methanol extract of leaves) andMEF (methanol extract of fruits). Then residual filmtoxicity method was applied to evaluate the insecticidal activity of EAL, EAF,MEL and MEF against adult Tribolium castaneum. In this study, the effectiveness of test samples was increased with the increase of exposure time and after 48 hrs of exposure, the lowest LD50was found to be 0.105 mg/cm2 for MEL. According to the intensity of activity, the toxicity was found in the order ofMEL > EAL > EAF > MEF. The overall results of this study suggest that leaves of Lawsonia inermis has potential insecticidal effect which might be used in pest control.