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The varietal resistance of thirty-one cowpea cultivars to cowpea bruchid, Callosobruchus maculatus (Fab.)
[Coleoptera: Chrysomelidae] was investigated in the laboratory at 28+2oC and 75+5% relative humidity. The
cultivars namely: MIT04K-339-1, MIT07K-291-92, MIT07K-211-108, MIT07K-292-10, EIT07K-303-1,
EIT07K-243-1-10, EITO7K- 234-1-5, IT067-154-1, IT96-619,IT845-2246-4, IFE BROWN, MIT06K-128,
MIT07K-188-49, MIT0K-835-45, MIT07K-318-33, MIT07K-309-44, MIT06K-281-1, MIT07K-187-24,
MIT06K-124, MIT04K-219-2, MIT04K-321-2, MIT07K-304-9, MIT03K-337-6, MIT06K-121, MIT07K-194-
3, MIT98K-503-1, EIT04K-221-1, EIT07-291-69, EIT07K-299-4, EIT03K-369-3 and EIT97K-499.35 were
provided by the Cowpea Seeds Unit, International Institute for Tropical Agriculture (IITA), Ibadan, Oyo State,
Nigeria. The parameters accessed include morphological features of cowpea cultivars, number of eggs laid,
percentage adult emergence, percentage seed damage, percentage weight loss and percentage seed viability.
Results showed that cultivars MIT04K-399-1, MIT07K-299-92, IT96-610, MIT06K-281-1, MIT07K-187-24,
MIT06K-121, MIT07K-304-9 and EIT07K-291-69 were the least susceptible to C. maculatus with percentage
seed damage of zero. The most susceptible cultivar was IFE BROWN with highest number of eggs laid of
35.36, highest percentage adult emergence of 79.19%, highest percentage seed damage of 31.45%, highest
percentage weight loss of 10.9% and least percentage seed viability of 60%. In other to reduce post harvest loses
of cowpea, the results obtained from this study suggested that planting the resistant cowpea cultivars such as
MIT04K-399-1, MIT07K-299-92, IT96-610, MIT06K-281-1, MIT07K-187-24, MIT06K-121, MIT07K-304-9
and EIT07K-291-69 may reduce infestation and damage to seeds by cowpea bruchid, C. maculatus and
enhanced the self life of cowpea. This will also boost food security programme in Nigeria.
Key words: Callosobruchus maculatus, cowpea cultivars, varietal resistance, susceptibility, seed damage,
weight loss, viability