Evaluation of the Insecticidal Properties of Two Plant Powders and Extracts for Protecting Wheat Grains Against Tribolium Castaneum (Herbst) [Coleoptera: Tenebrionidae]

Background and Objective: Plant-based insecticides are widely recognized for their cost-effectiveness and eco-friendly properties in protecting stored grains. During storage, various insect pests target stored grain products, with Tribolium castaneum being one of the most destructive. The objective of this study is to evaluate the insecticidal properties of two plant powders and their extracts in protecting wheat grains against Tribolium castaneum infestation. Materials and Methods: This study observed the efficacy of Ricinus communis and Senna alata leaf powders and extracts in managing T. castaneumunder laboratory conditions at 28±2°C and 75±5% relative humidity. The powders were tested at dosages of 0.2, 0.4, 0.6, 0.8, and 1.0 g per 20 g of wheat grains, while the extracts were applied at concentrations of 0.1, 0.2, 0.3, 0.4, and 0.5 mL per 20 g. Parameters examined included mortality rates, lethal doses (LD₅₀ and LD₉₀), progeny suppression, weight loss percentage, seed damage, and the Beetle Perforation Index (BPI). One-way ANOVA and probit analysis were used to analyse the data gotten from the experiment. Statistical differences are determined when p<0.05. Results: The findings revealed that R. communis powder achieved 50% adult mortality at 1.0 g per 20 g of wheat grains within one day, whereas S. alata powder caused 60% mortality at the same rate. Similarly, the extract of R. communis at 0.5 mL per 20 g induced 76.67% adult mortality after one day, while S. alataextract achieved 86.67% mortality under the same conditions. Each plant’s powders and extracts effectively inhibited egg-laying, progeny production, weight loss, and seed damage. Among the two, S. alata demonstrated superior efficacy in both powdered and extract forms. Conclusion: Incorporating R. communis and S. alata into pest management strategies can significantly reduce the economic impact of T. castaneum, ensure the availability of viable seeds for planting, and enhance food security in Nigeria and other developing countries.