Insecticidal effect of essential oil and powder of Mentha pulegium L. leaves against Sitophilus oryzae (Linnaeus, 1763) and Tribolium castaneum (Herbst, 1797) (Coleoptera: Curculionidae, Tenebrionidae), the main pests of stored wheat in Morocco

Stored grains are threatened by several insects, leading to losses in quality and quantity. Several studies have revealed the risks of using chemicals that can cause serious health problems for humans. It is in this perspective that the objective of our work should be seen: It was to assess the effect of the essential oil and leaf powder of Mentha pulegium against Sitophilus oryzae and Tribolium castaneum adults attacking post-harvest cereals. The insecticidal activity of the essential oil against these two insects was evaluated by three methods: contact, inhalation and ingestion. The ingestion method was used in the case of the leaf powder. The essential oil and leaf powder of Mentha pulegium exhibited insecticidal activity against Sitophilus oryzae and Tribolium castaneum adults ( Mentha pulegium essential oil caused up to 100% mortality of both insects). Both insects were influenced affected by the dose, exposure time and the method by which the insecticidal activity of the essential oil was demonstrated. Adults of Sitophilus oryzae were more sensitive to different concentrations of essential oil and leaf powder than those of Tribolium castaneum . The essential oil has no effect on the germination rate of soft wheat grains ( Triticum aestivum ). On the contrary, it acts positively by reducing the damage caused by these major stock pests. The data from this study could present an alternative solution for replacing synthetic insecticides for the protection of stored commodities.