Postharvest insect pests constitute major threats to food security because they cause qualitative and quantitative damage to agricultural produce. Therefore, eco-friendly and cost-effective measures should be used for their management. In this study, five botanical powders ( Trema orientalis and Crataeva religiosa leaves; and Citrus tangelo, Citrus maxima and Citrus aurantifolia peels) were admixed with Spintor® [1.25 active ingredient (a.i.) mg · kg ^–1] and evaluated as toxicants against Tribolium castaneum. Each botanical powder and spintor was solely applied at 1000 mg · kg ^–1 millet seeds. Spintor-botanical powder mixtures admixed at a ratio of 1 : 1 (w/w) were applied at 500 and 1000 mg · kg ^–1, corresponding to 0.313 and 0.625 a. i. mg · kg ^–1 for spintor in the mixtures, respectively. On the 14th day of exposure, the Citrus species admixed with spintor and applied at 500 mg · kg ^–1 evoked significantly (p < 0.05) higher percentage mortality (72.22–90.28%) than what was observed in the mixture of spintor with T. orientalis (22.08%) or the mixture of spintor with C. religosa (17.92%) applied at 500 mg · kg ^–1. There was a significant difference (p < 0.05) in the Kaplan-Meier estimates of the treatments against the insects. The time required to kill 50% of the assayed insects (LT50) when Citrus species were admixed with spintor at 500 mg · kg ^–1 (10 days) was shorter than 14 days observed in the mixture of spintor with T. orientalis or C. religiosa. Therefore, admixing spintor with any of the Citrus powders [at 1 : 1 (w/w)] applied at 500 mg · kg ^–1 seed is recommended for the protection of millet seeds against T. castaneum.,

The study’s objective was to assess the efficacy and to identify the toxic mechanisms of action of some plant-derived monoterpenes and yucca extract as alternatives to chemical insecticides against the red flour beetle, Tribolium castaneum. Carvone, 1,8-cineole, cuminaldehyde, and linalool, as well as Yucca schidgera extract, were the control agents whose efficacy against the red flour beetle was tested in the laboratory and compared to malathion. The criteria for evaluating efficacy were the effects of the tested compounds on adult mortality and red flour beetle progeny. Furthermore, the effects of the control agents on some enzymes (Acetylcholinesterase, ά-amylase, and alkaline phosphatase) in T. castaneum were investigated. Moreover, the effect of the tested control measures on weight loss of treated wheat grain was studied. The tested substances showed a high ability to control T. castaneum with regard to adult mortality and offspring production, especially when used as fumigants. For adult mortality, malathion showed the highest potential against T. castaneum as a fumigant, followed by carvone, yucca extract, cuminaldehyde, linalool, and 1,8-cineole with LC ₅₀ values of 0.05, 331.5, 365.1, 372.2, 460, and 467.5 mg · 1000 cm ^–2 after 72 hours, respectively. The highest reduction in progeny was for malathion followed by carvone, linalool, cineole, yucca extract, and cuminaldehyde with reduction percentages of 100, 90, 89.3,79.4 and 65.8%, respectively. The tested compounds significantly affected acetylcholinesterase activity, alpha-amylase activity, and alkaline phosphatase in the red flour beetle. There was no significant reduction in the weight of wheat grains treated with the tested materials compared to the untreated healthy grains. Finally, the tested compounds as fumigants, especially 1,8-cineole, can be considered as effective alternatives to control the red flour beetle.