IMPACT OF RE-DRYING TREATMENT ON BEAN WEEVILS (CALLOSOBRUCHUS MACULATUS) AND NUTRITIONAL COMPOSITION OF INFESTED STORED COWPEAS

Abstract

This study investigated the impact of re-drying treatments- drying at 40 °C and 60 °C, sun drying, and a non-dried control on the post-harvest quality of cowpea (Vigna unguiculata) and its resistance to Callosobruchus maculatus infestation during storage. Treated cowpea grains were stored for 84 days, with key metrics assessments including C. maculatus egg hatchability (28 days), adult emergence (12 days), grain damage, weight loss, and nutrient changes. Drying at 60 °C significantly reduced egg hatchability and adult beetle emergence (p ≤0.05), resulting in the lowest percentage of grain damage and weight loss. Sun drying and drying at 40 °C exhibited moderate protective effects, whereas the control group showed the highest infestation and deterioration. Nutritional analysis revealed that while high-temperature drying slightly decreased protein content, it recorded the highest carbohydrate and crude fiber. These findings suggest that re-drying, especially at 60 °C, is a promising post-harvest strategy for controlling bruchid infestation and preserving cowpea grain quality during storage.