Evaluation of Four Cowpea Lines for Bruchid (Callosobruchus maculatus) Tolerance

Abstract

Cowpea, an important legume in many developing countries, is face by varieties of biotic stresses. Among them is the infestation of stored grains by Callosobruchus maculatus, an insect pest capable of causing high grain loss both in quantity and quality. However, resistant genotypes were developed to reduce the damages on stored seed grains by this insect pest. The study evaluated the level of resistance in four cowpea genotypes collected from the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. These cultivars were infested with bruchids for three days in four replicates. Comparative data were then collected from the samples study for analysis. This study showed that there was a positive perfect correlation between percentage pest tolerance and the number of undamaged seeds. The study also showed that most of the resistant genotypes were susceptible with TVx 3236 being the most susceptible. IT99K-494-6 and IT84S-2246-4 suggested in earlier literatures to be resistant to bruchid attack were also susceptible. However, IT81D-994 showed a moderate tolerance to the infestation with percentage pest tolerance of 60. It is therefore imperative that bruchid tolerance evaluation be done periodically on released resistant genotypes to ascertain the stability and durability of their resistance against bruchid infestation.

Key words: Cowpea, Callosobruchus maculatus, Pest tolerance, Pest infestation, Susceptibility