Abstract
Insect infestation can alter the quality and nutritional composition of cereal and legume grains during storage. This study evaluated the nutrient changes in common bean and maize cultivars infested with Acanthoscelides obtectus and Sitophilus zeamais, respectively, after six months of storage. The common bean cultivar NUV6 and the maize cultivar CMS 8704 were highly susceptible, whereas the common bean cultivar FEB-190 and the maize cultivar CMS 8501 were moderately resistant. Adults of A. obtectus emerged earlier in common bean cultivars than adults of S. zeamais in maize cultivars. Infestation significantly altered the nutritional composition of maize, markedly reducing macronutrients such as protein and crude fat; this decline was consistent across cultivars, highlighting the destructive impact of pests on grain quality. The relative increase in ash content of infested samples indicated degradation and possible contamination with insect by-products rather than a gain in beneficial minerals. Whereas most nutrients were depleted, copper content remained relatively stable, suggesting that nutrients differ in their vulnerability to insect activity. The effect of infestation was significant overall, but the cultivar × infestation interaction was not significant for the macronutrients. Principal component analysis (PCA) revealed relationships among nutrients and nutritional patterns that differentiated the cultivars. Overall, insect infestation strongly affected the nutritional quality of stored grains. These findings can support the development of improved postharvest storage and pest management strategies that protect household food security and preserve the value of stored staple crops.