Toxic and oviposition deterrence activities of essential oils from Citrus sinensis (L.) Osbeck and Citrus paradisi (Macfarlane) fruit peel against adults of Tribolium castaneum (Herbst)

The red flour beetle, Tribolium castaneum (Herbst), is one of the most destructive pests attacking stored grain products all over the world. Serious problems assossiated with using synthetic chemical insecticides have strongly demonstrated the need for applying alternative safe compounds such as plant essential oils. The present experiment was conducted to evaluate fumigant toxicity of essential oils from the fresh fruit peel of two Citrus species namely, Citrus sinensis (L.) Osbeck and Citrus paradisi (Macfarlane) against 1 to 7-days-old adults of T. castaneum under laboratoryconditions. Moreover, oviposition deterrence activity of sublethal concentrations of the oils were assessed on the female beetles. All experiments were carried out at 27 ± 1 °C and65 ± 5% r. h. in darkness. Findings indicated the high fumigant toxicity of both essential oils. According to probit analysis, there was no significant differences between C. sinensis (LC50 = 7.27 µl.l-1 air) and C. paradisi (LC50 = 7.70 µl.l-1 air) essentialoils. Also, oviposition deterrence activity of the essential oils was significantly increased as concentrations of the oils were increased from 500 to 2500 ppm. In general, the results of our study demonstrated the high efficacy of C. sinensis and C. paradisi oils against T. castaneum.