Varietal Susceptibility of Improved Cowpea Vigna unguiculata (L.) (Walp.) Cultivars to Field and Storage Pests

Cowpea, Vigna unguiculata is widely cultivated in the tropics and subtropics as food for man and livestock. The crop is highly prone to pests and diseases which limit its production. Resistant cowpea varieties have become increasingly important in the management of both field and storage pests. Three improved cowpea varieties and one local variety were screened for their susceptibility to field and storage pests. The experiment was conducted in a randomized complete block design with four treatments and three replications. The different pests infesting the plants were identified and counted. Aphids and thrips were scored on a scale of 0-5, depending on the levels of infestations. Natural enemies’ numbers, leaf damage, pod damage and yield were assessed. Callosobruchus maculatus infestations during storage and weight reduction were determined over a six week period. Aphids and M. sjostedti score, M. virtrata and Empoasca sp. numbers did not differ significantly; however, significantly more pod sucking bubs attacked the local variety than the improved varieties. Natural enemies’ numbers on the various cultivars did not differ significantly. Yield was however significantly better in the improved varieties. The local variety suffered the largest weight reduction (20.91%) during storage while Nhyira suffered the least weight reduction of 4.23%. The use of improved varieties and application of pests’ control measures will increase cowpea production in Ghana.