OBSERVATIONS OF THE INSECT COMPLEX OF COWPEA (VIGNA UNGUICULATA (WALP) IN ABRAKA, A NON-COWPEA GROWING AREA, SOUTHERN NIGERIA.

Abstract

The Sudan Savannah, the drier northern Nigeria is the major belt for the cultivation of cowpea (Vigna unguiculata (L) Walp. The West and East of southern Nigeria, however, began its cultivation recently. The crop constitutes a main food for many Nigerians and because of this, the crop performance and all factors which are constraints to its production are being studied. Cowpea was cultivated in Abraka, a non-major cowpea cultivation region, during the early and late planting seasons of 2005 to study the insect pests spectrum (insect complex) which decimate the crop. Their relative abundance were also determined. The results indicated that in the early season, there were 8 insect orders; 25 families and 37 species. Coleoptera had the highest species 11, with relative abundance of 29.6%. Others were heteroptera, 8 species (21.6%), diptera, 5 species (13.5%), homoptera, 4 species (10.8%), orthoptera, 3 species (8.1%), hymenoptera, 3 species (8.1%), lepidoptera, 2 species (5.4%) and thysanoptera, 1 specie (2.7%). During the late season, coleoptera were the highest, 10 species (28.6%). Others were heteroptera, 9 species (25.7%), diptera, 4 species (11.4%), homoptera, 4 species (11.1%), orthoptera, 3 species (8.6%), hymenoptera, 2 species (5.7%), lepidoptera, 2 species (5.7%) and thysanoptera, 1 specie (2.9%). Ootheca mutabilis Sahl, Aphis craccivora Koch, Megalurothrips sjostedti Trybom, Maruca vitrata Fab and coreid bugs such as Clavigralla tomentosicollis Stal, Anoplocnemis curvipes Fab, C. shadabi, Aspavia armigera Fab, Nezara virudula L, Mirperus jaculus Thunb were the commonest major insect pests on cowpea at Abraka. More insect species occurred in the early season than late in the study area.