Laboratory Screening of Seeds of Some Cowpea Cultivars (Vigna unguiculata) for Tolerance to Cowpea Beetles (Callosobruchus maculatus) in a Hot Humid Environment

Seeds of five cowpea cultivars (Ife Brown, Ibadan Local, Ife BPC, Mala and Oloyin) were screened for tolerance to cowpea beetles (Callosobruchus maculatus). The screening was done in the Seed Testing Laboratory of the Institute of Agricultural Research and Training, Obafemi Awolowo University, Moor Plantation, Ibadan. Seed samples were inoculated with eggs of Callosobruchus maculatus while control experiments were treated with phostoxin to prevent infestation. Common storage methods adopted by the African cowpea farmers were also evaluated for their efficacy. The results showed that storage methods (S) Variety (V) and Treatment (T) were highly significant for all parameters assessed, while phostoxin treated seeds stores relatively better than non-phostoxin treated seeds. Similarly, cowpea seeds stored in plastic containers were better preserved than those stored in tins and earthen pots. In fact, storing cowpea in nylon bags should be discouraged. Absolute seed damaged was observed from seeds stored in nylon bags. Percentage pest tolerance was observed to vary directly with number of undamaged seed, remained seed weight and reduced weight loss, while Oloyin was able to combine gene for C. maculatus resistance with good storability. Implications of correlation coefficients (r) among seed characters for the tested cultivars were discussed.