Biological Performance and Seed Damage of Callosobruchus maculatus F. on Four Improved Cowpea [Vigna unguiculata (L.) Walp.] Varieties

Aims: Cowpea, Vigna unguiculata (L.) Walp., is an important grain legume in sub-Saharan Africa, but its postharvest storage is constrained by the cowpea weevil, Callosobruchus maculatus (F.). Although several improved varieties have recently been released in Burkina Faso, their susceptibility to C. maculatus under storage conditions remains poorly documented, limiting recommendations to farmers and extension services. This study assessed the biological performance of C. maculatus and the resulting seed damage in four improved cowpea varieties (Issa Sosso, Makoyin, Nerwaya and Yipoussi) under laboratory conditions. Study Design: The study was conducted at the Laboratory of Fundamental and Applied Entomology, Joseph KI-ZERBO University, Burkina Faso. Methodology: A completely randomized design with four varieties and 12 replicates per variety was used. In each replicate, one newly emerged C. maculatus pair was exposed to 20 uninfested seeds in a Petri dish under no-choice conditions for 12 h for oviposition, at 30±2°C, 45% relative humidity, and a 12L:12D photoperiod. Results: Seed dimensions differed significantly among varieties, with Nerwaya having the largest seed area (52.58±0.89 mm²) and Issa Sosso the smallest (47.77±0.62 mm²). Oviposition differed significantly (P=.008), from 74.67±5.45 eggs on Nerwaya to 105.58±6.65 eggs on Makoyin. Egg hatching and immature mortality varied significantly, whereas development time and adult emergence did not differ significantly. Nerwaya received the fewest eggs and had the lowest seed damage, but the highest egg hatching (85.86±1.74%) and lowest immature mortality (17.02±2.47%). Females were generally larger than males. Nerwaya had the lowest perforation (49.17±5.83%) and weight loss (14.19±1.51%), whereas Issa Sosso had the highest values (81.67±2.41% and 28.57±2.08%, respectively). Conclusion: All varieties supported C. maculatus development, but seed damage differed substantially. Nerwaya combined lower oviposition and damage with higher egg hatching and lower immature mortality, indicating that reduced oviposition did not necessarily reduce immature survival. On the basis of the damage indicators, Nerwaya showed the most favourable postharvest profile and may contribute to integrated management of C. maculatus during cowpea storage.