Evaluation of responses of five cowpea (Vigna unguiculata (L.) Walp.) varieties to field infestation by major insect pests of cowpea

The study was conducted to evaluate yield response of five cowpea (Vigna unguiculata (L.) Walp.) varieties to field infestation and damage by major insect pests of cowpea. Three local varieties of cowpea, namely, Sokoto, Oloyin and Drum, and two International Institute of Tropical Agriculture (IITA) varieties, IT 90K-277-2 and IT90K-76, were planted on the Teaching and Research Farm of University of Agriculture, Abeokuta (UNAAB), Ogun State, Nigeria in September, 2006 and repeated in September, 2007. The experiment was laid out in Randomised Complete Block Design in split plots arrangement. Insecticidal spray constitutes the main plot while variety was the sub-plot. The main plot size was 19.4 m × 19 m and each of the sub-plot was 2.4 m × 3 m. The space between sub-plots was 1 m. Data from the sprayed plots were significantly (P < 0.05) higher than the unsprayed ones in the two seasons. Irrespective of season, the unsprayed plot of IT 90K-277-2 has a significantly (P < 0.05) high incidence of Ootheca mutabilis. The local variety, “Drum” has the highest incidence of flower thrip – Megalurothrips sjostedti in the two planting seasons. The highest mean number of peduncles/plant and pods/plant was in “IT 90K-277-2”. In both seasons, “IT90K-76” has a significantly (P < 0.05) lower number of damaged seeds and pods and “Oloyin” a significantly (P < 0.05) higher mean number of total pod sucking bugs. The grain yield was in the order IT90K-76 > Oloyin > IT 90K-277-2 > Sokoto > Drum.