Evaluation of Some Plant Essential Oils as Repellent and Toxicant Against Trogoderma Granarium (Everts) (Coleoptera: Dermestidae)

The essential oils from four medicinal plants viz., Azadirachta indica, Curcuma longa, Nigella sativa and Piper nigrum were assessed at a rate of 5, 10, 15 and 20% concentrations against khapra beetle, Trogoderma granarium (Everts) for their potential to protect stored wheat grains in term of their repellency and toxicity. Essential oils of A. indica gave the highest mean repellency (90.00%) at 20% concentration. The minimum value of repellency (23.56%) was observed in case of P. nigrum at 5% concentration. Highest value of mortality (30.68%) was recorded in case of A. indica, while minimum value of mortality (14.82%) was observed after 30-days of treatment application at 20% concentration. Similarly, after 5days of treatment application at 5% concentration, highest mortality was 3.45% in case of A. indica and minimum value was 2.24% where application of P. nigrum was carried out. Essential oils from these plants caused significant T. granarium mortality and deterred the larvae from feeding on wheat grains. Essential oils of these plants could serve as the foundation for development of new botanical insecticides.