Response of some Bambara groundnut [Vigna subterranea (L.) Verdc.] seeds to Callosobruchus subinnotatus infestation in Gombe

Abstract

Despite the economic and nutritional status (rich in lysine and methionine) of Bambara groundnut seeds, it is been considered as underutilized and susceptible to infestation by insect pests in storage. The current study was aimed to determine if Callosobruchus subinnotatus , the Bambara groundnut seed beetles, could infest eight different types of Bambara groundnut seeds. Significant varietal differences were observed in resistance to storage insect pests based on progeny emergence, weight loss, susceptibility index, and development time. The highest progeny emergence was recorded in Deep brown with white eyes (34.62%), Cream with black stripes (33.71%), and Cream with brown eyes (30.99%), indicating high susceptibility. In contrast, cream with black eye (18.56%) and Brown with white eye (18.97%) showed lower emergence, suggesting stronger resistance. Percentage weight loss (PGWL) was highest in Cream with black eyes (5.7%) and Deep brown with white eyes (5.3%), while the least was in Cream with brown stripes (1.5%). Susceptibility index and median development time further confirmed varietal resistance, with CBEB (SI = 1.6; MDT = 104.2 days) and CWBS (SI = 2.6) showing strong resistance, while Black with White Eye (SI = 7.7; MDT = 28.7 days) and Cream with Black Eye (SI = 8.8; MDT = 25.8 days) were highly susceptible. Cream with Brown Eye had the highest retained seed weight (8.52 g), while Black Bambara groundnut showed the highest PGWL (6.88%) and the lowest seed retention (3.21 g), indicating severe damage. As a result, for resource-strapped subsistence farmers, using resistant varieties like Cream with a black eye and brown stripes may be the most straightforward and cost-effective option to improve Bambara groundnut varieties during storage.