Relative tolerance of eight cowpea varieties to infestation and damage by cowpea weevil, callosobruchus maculatus.
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Date
2026
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Busitema University
Abstract
Cowpea (Vigna unguiculata L) is an important grain legume in sub-Saharan Africa and a major source of proteins, vitamins, and minerals. In Uganda, its production and storage is greatly affected by the cowpea weevil (Callosobruchus maculatus), which can cause severe grain loss and damage. This study evaluated the relative tolerance of eight cowpea varieties (NARO COWPEA series, SECOW 3B, and SECOW 2W) to infestation and damage by Callosobruchus maculatus, under controlled laboratory conditions at Busitema university. The experiment used a completely randomized design (CRD) with nine replications, with 100 seeds per replicate infested with 15 adult cowpea weevils. Data were collected on oviposition, incubation and development period, F1 adult emergence, susceptibility index, weight loss, seed damage, and seed coat texture. Analysis of variance and Tukey’s HSD post-hoc test at P <0.05 showed significant differences among varieties. NARO COWPEA 4, 5, and 2 showed highest tolerance, with low adult emergence and seed damage, while NARO COWPEA 3, 1, and SECOW 3B where the most susceptible to weevil damage. NARO COWPEA 6 also recorded low weight loss. The rough seed coat of NARO COWPEA 4 and 5 appeared to contribute to resistance while low adult emergence in NARO COWPEA 4 despite high oviposition suggests antibiosis. Overall, NARO COWPEA 4, 5, and 2 are recommended for storage and as a useful genetic resource in breeding programs. There adoption will reduce postharvest losses, improve food security and reduce dependence on synthetic insecticides. Further studies should investigate the biochemical mechanisms of tolerance of NARO COWPEA 4, 5, and 2 to the cowpea weevil and farmers should integrate these tolerant varieties with proper postharvest handling practices such as proper drying and hermetic storage technologies for a holistic Callosobruchus maculatus pest management in Uganda.
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Undergraduate research report
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Citation
Isabirye, K. (2026). Relative tolerance of eight cowpea varieties to infestation and damage by cowpea weevil, callosobruchus maculatus. [Unpublished undergraduate research report]. Busitema University.