Many investigations have been conducted to replace synthetic chemicals with natural and economical compounds to control stored–product pests in the last decades. In the present study, biological activity of essential oils of the fruit peels of two Citrus species including Lemon (Citrus limonium Risso.) and Tangerine (Citrus reticulata Blancko.) were examined on the adults and eggs of cowpea seed beetle (Callosobruchus maculatus Fab.). The oils were extracted from fresh peels by hydro- distillation method using a Clevenger apparatus. The bioassays were carried out on zero- to 2-day old adults and zero- to 2-day old eggs in the laboratory conditions. The adults were exposed to different oil concentrations for 3-24 hour periods in enclosed vials. The essential oils of C. reticulata and C. limonium caused respectively 100and 91% mortality in adults after 24 h by the presence of the highest concentration (285 μlL-1). In all bioassays, adult mortality was associated positively with oil concentration and exposure time. Based on fumigant 24 h LC50 estimates on adults, the essential oil of C. reticulata proved to be more toxic (LC50= 33 μlL-1) and that of C. limonium lower toxic (LC50= 235 μlL-1). The eggs were exposed to different oil concentrations for 6 days periods in enclosed vials. The bioassays on eggs indicated that the lower LC50 value was attained by C. reticulata oil (LC50 = 38 μLl-1) and the higher LC50 value by C. limonium oil (LC50 = 82 μLl-1). In summary, the essential oil of C. reticulata exhibited higher lethal activity against adults and eggs.

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