Insecticidal, Antifeedant and repellent efficacy of certain essential oils against adult rust-red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae)

Stored grains represent main constituent of food in Egypt. Tribolium castaneum comes on the top of stored grain pests causing up to 40% weight reduction of stored grains. Therefore, its control is urgent. This study aimed to evaluate the insecticidal activity of four essential oils (Eos) extracted from Allium sativum (garlic), Cinnamomum camphora (camphor), Syzygium aromaticum (clove) and Brassica junicea (mustarda) against adults T. castaneum. Also, the effects of these oils on biology and physiology of T. castaneum were tested. In addition, the effect of the tested oils on wheat seeds germination was determined. Gas chromatograph - Mass spectrophoto- metry was used to analyze the major constituent of the tested essential oils. Results indicated that the four tested essential oils have insecticidal, anti-feedant, and repellent activities against adult T. castaneum. Clove has the highest insecticidal activity with LC50 (1.44 mg/kg) followed by garlic (2.09 mg/kg), Camphor (2.75 mg/kg), and Mustard (3.67 mg/kg). the results also showed that clove oil had the highest residual effect, its insecticidal effect extended to the seventh week from the treatment. Results also showed that the clove and camphor have adverse effect on T. castaneum adult physiology. Also, the tested Eos to some extent affect seed germination, meanwhile the garlic and camphor oils showed the lowest effect. Mass spectra results revealed different bioactive components, as Fatty acids, decanes, cosane, and sulphide groups. Finally, results demonstrated that clove and garlic oils showed low cytotoxic effect. In conclusion. The tested essential oils could be considered as promising effective and safe alternatives for synthetic insecticides to control stored grain pests.