Anti-nutritional factors in cowpea cultivars and their effects on susceptibility to Callosobruchus maculatus (Fab.) [Coleoptera: Bruchidae] infestation

Thirty-one cowpea cultivars from IITA in Nigeria were investigated for their antinutritional factors to determine their susceptibility to cowpea bruchid, Callosobruchus maculatus (Fab.) [Coleoptera: Chrysomelidae] infestation. Percentage seed damage and pest tolerance, Phytate, tannins and oxalate contents were determined using standard methods. The result showed significant variations in both % seed damage and pest tolerance among the cowpea cultivars tested. 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 100% pest tolerance. The result of anti-nutritional factors clearly showed that cowpea seeds contain more phytate than oxalate and tannin. The mean phytate content in seeds was (3.10 mg/g) which was about three times higher than that of oxalate (0.78 mg/g) and five times higher than tannins (0.31 mg/g). Cultivar MIT04K-339-1 recorded the highest amount of phytate while cultivar MIT03K-337-6 recorded the lowest. The amount of oxalate ranges from 0.42 mg/g to 0.92 mg/g. Cultivar IT96-610 recorded the highest amount of tannin while cultivar MIT03K-337-6 recorded the lowest amount of tannin. This study revealed variations in the anti-nutrients composition among the cowpea cultivars. These variations contribute to the susceptibility of cowpea to C. maculatus infestation.