Comparative efficacy of five essential oils from local plants and their major constituents in controlling the stored wheat pest Trogoderma granarium Everts (Coleoptera: Dermestidae)

In our investigation, five essential oils (EOs) from local plants (Rosmarinus officinalis, Citrus aurantium, Eucalyptus globulus, Mentha spicata and Cupressus sempervirens) and their major constituents (EOCs) were evaluated against larvae of Trogoderma granarium, a stored-product insect species of economic importance. The chemical profile of some plant EOs tested was characterized and the results revealed a composition dominated by linalool, carvone and p-cymene for Citrus aurantum, Mentha spicata and Eucalyptus globulus, respectively. In a second series of bioassays by fumigation, EOs and EOCs were tested against larvae. Thus, based on LC₅₀ values, R. officinalis EO (5.53 μL/L of air), Limonene (7.07 μL/L of air) and C. aurantium (8.71 μL/L of air) appeared as the most toxic EOCs to larvae, followed by Menthol (26.48 μL/L of air), Eucalyptus globulus (LC₅₀ = 33.32 μL/L of air) and Carvone (51.30 μL/L of air). The repellent activity was estimated by the 5 repellent concentration (RC₅₀). Thus, a significant higher number of larvae were repelled by E. globulus EO (RC₅₀ = 3.27 μL/mL), followed by Linalool (9.65 μL/mL) and Limonene (17.37 μL/mL). Our results demonstrated that the EOs and their major constituents have the potential to be developed as an alternative to synthetic insecticides against T. granarium. Further research is required to give additional information on the activities of the potent EOCs under open-field conditions.