Abstract

Insect pests constitute serious threat to cowpea production in sub-Saharan Africa. In some severe situations, total yield loss results. Chemical control, although most effective, is very costly, hazardous and unsustainable. Investigation of other control options such as cultural practices that are environment friendly is critically important. This paper reports the effects of four levels of phosphorus fertilizer application (0, 15, 30 and 45 kg P₂O₅ ha^-1) on insect population, damage and grain yield of four cowpea varieties (IT91K-180, IT95M-118, TVu 1890 and Vita 7) planted at research farm of International Institute of Tropical Agriculture (IITA), Nigeria. Data were collected on insect counts, pod evaluation index and damage by Aphis craccivora, Megalurothrips sjostedti, Maruca vitrata and pod-sucking bugs. Results indicated that damage by A. craccivora, M. sjostedti and M. vitrata were significantly (P < 0.05) lower at 30 and 45 kg P₂O₅ ha^-1 and consequently higher grain yields were obtained.

Key words: Cowpea, grain yield, insect pests, pod evaluation index, phosphate fertilizer.