Efficacy of Ammi majus (Apiaceae) and Mentha microphylla (Labiatae) as Protectants of Wheat Grain Against Sitophilus oryzae L. (Coleoptera: Curculionidae)

Background: Rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae) which is one of the most common species to infect wheat during storage. Low effectiveness of the chemical control strategy against this pest has been reported. Plant extracts either essential oils or powders have been reported to be an interesting source of new botanical pesticides due to their activity against various insect pests. Methods: The effect of leaf powders of Khella, Ammi majus (Family: Apiaceae) and Spearmint, Mentha microphylla (Family: Labiatae) against S. oryzae as well as the effect on germination was tested after six months of wheat storage compared with untreated wheat. Results: The efficacy of A. majus and M. microphylla leaf powders as insecticides against rice weevil was differed depending on the type of plant, time, and dose. A. majus and M. microphylla leaf powders proved toxic to S. oryzae at 2.0, 5.0, and 8.0 g/10.0 g wheat grain, although they differed in their efficacy. At the end of six months of treatment, A. majus leaf powder at 8.0 g/10.0 g wheat grain considerably outperformed M. microphylla leaf powder in terms of mortality rate (80.59) and adult emergence inhibition (25.51%) of S. oryzae. The usage of the powders considerably reduced grain damage and rice weevil infestation after 180 days of treatment (≈six months), resulting in treated wheat grains germinating by more than 70% compared with untreated wheat grains by only 24%. Conclusion: Leaf powders of A. majus and M. microphylla protecting stored wheat grains from rice weevil infestation after six months of treatment, so they can be used as a potential control in IPM programs.