Susceptibility of Six Local and Four Improved Cowpea Cultivars to Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) Infestation in North Eastern Nigeria

The susceptibility of seeds of six local (Banjara, Borno brown, Gwallam, Kanannado brown, Kanannado white and Saddam) and four improved (189KD-288, IT89KD-391, IT90K-82-2 and IT97K-499-35) cowpea cultivars that were commonly grown in north eastern Nigeria to infestation by the cowpea storage bruchid, Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) was evaluated in the laboratory at 30oC - 35oC and 60% - 65% RH. Parameters tested include the number of bruchid eggs laid and adults emerged, percentage seed damage, severity of seed damage, seed susceptibility index and bruchid developmental period. All parameters collected were analyzed using the analysis of variance (ANOVA). The mean number of bruchid eggs laid and adults emerged, percentage seed damage, severity of seed damage and seed susceptibility index were generally significantly different amongst the ten different cowpea cultivars. Mean bruchid developmental period, was however, not significantly different amongst the cowpea cultivars tested. The seeds of all ten cowpea cultivars (local and improved) were either moderately or highly susceptible to infestation by C. maculatus. Results obtained in this study indicated the need for breeders to develop high-yielding cowpea cultivars that are well adapted to cultivation in the north eastern region of Nigeria, with relatively high resistance to attack by the bruchid beetle.