Insecticidal Activity of Essential Oils of Four Medicinal Plants Against Different Stored Grain Insect Pests

Studies were carried out to investigate the insecticidal activity of essential oils of four locally grown plants such as Datura stramonium, Eucalyptus camaldulensis, Moringa oleifera and Nigella sativa against three major insect pests viz., Tribolium castaneum, Trogoderma granarium and Cryptolestes ferrugineus responsible for economic loss to stored commodities. Test insects were fumigated with concentrations of 5, 10, 15 and 20 µl/L under laboratory conditions at 30±2°C and 65±5% relative humidity. Essential oils fumigation significantly affected the mortality at all levels of concentration and exposure periods. Among essential oils D. stramonium was found to be the most toxic against T. granarium (14.46%) and C. ferrugineus (28.49%) while N. sativa showed the highest fumigant mortality (20.06%) against T. castaneum. Overall results show that C. ferrugineus was found to be the most susceptible test insect with 23.79 % mean mortality followed by T. castaneum (17.11%) and T. granarium (12.27%). Higher mortality was found to be concentration and exposure time dependent. The results demonstrate that the essential oils of investigated plants can be used as fumigant to control insect pests of stored products.