Plant-Based Repellency Against Tribolium castaneum for Preserving Mesquite Pod Flour as Livestock Feed

In arid and semi-arid regions, mesquite (Prosopis laevigata) pods represent a strategic feed resource for low-input livestock systems; however, the utilization of mesquite pod flour is severely limited by insect infestation during storage. This study evaluated the repellent effectiveness of Ricinus communis leaves and stems as plant-based additives for preserving mesquite pod flour against storage insects, primarily Tribolium castaneum (Coleoptera: Tenebrionidae). Dose-dependent repellency was assessed in a three-chamber choice-test system at concentrations of 1, 5, 10, and 20% (w·w−¹), combining short-term laboratory assays with a 14-month storage experiment under ambient conditions representative of rural dryland systems. R. communis leaves exhibited a strong concentration-dependent repellent effect, consistently outperforming stem material. Logistic regression indicated that each 1% increase in leaf concentration increased the odds of insects remaining in the untreated substrate by 17%. Long-term storage assays showed that botanical additives altered insect population structure, while only R. communis leaf powder at 10% showed lower total insect abundance relative to the control. Proximate analysis revealed additional protein contribution from R. communis leaves, while ricin-like proteins remained at low concentrations in vegetative tissues. Overall, the results validate a traditional preservation practice and support the use of R. communis leaf biomass as a plant-based additive for protecting mesquite flour in dryland livestock systems.