Repellency and toxicity of essential oils from Cymbopogon martinii, Cymbopogon flexuosus and Lippia origanoides cultivated in Colombia against Tribolium castaneum

A large number of plant essential oils have been used against diverse insect pests. Unlike conventional pesticides, usually these natural products present less risk to humans and the environment. This study was conducted to determine the repellent activity and toxicity of the essential oils isolated from Cymbopogon martinii palmarosa, Cymbopogon flexuosus lemongrass, and Lippia origanoides wild oregano against Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), using the area preference and contact toxicity on filter papers methods, respectively. The repellent action of the oils decreased in the order Cymbopogon martinii > C flexuosus approximate to L origanoides. All oils were more effective as repellents than the commercial product IR3535. Tested oils also depicted low toxicity, showing less than 20% lethality at maximum tested concentration (1.2 mu L/cm(2)) and exposure period (72 h). These results suggest that the essential oils evaluated in this study may be useful in repellent formulations against T. castaneum. (C) 2012 Elsevier Ltd. All rights reserved.