Monitoring Insect Complex of Cowpea (Vigna Unguiculata (L) Walp in Asaba, a Non-Cowpea Growing Area, Southern Nigeria
By EBENEZER OGHENEWORO EGHO
The cultivation of cowpea (Vigna unguiculata (L.) Walp extended recently from northern Nigeria, its main production region, to the eastern and western states of southern Nigeria. As a crop largely depended upon for food in Nigeria, its growth and yield have become a focus and all factors that have adverse effect on it wherever it is grown, have to be studied. Asaba Campus, Delta State University, formerly Bendel State College of Agriculture, is well known for crop production. Cowpea is presently in cultivation in this new non-cowpea producing region. Studies were conducted in the early and late planting seasons of 2005, to determine the insect complex of cowpea and their relative abundance, in Asaba. The results showed that there were 10 insect orders, 34 families and 50 species in the early season. Coleoptera were the most abundant with 13 species (26.0%), while the thysanoptera and demaptera were each one species (2.0%) to constitute the least. In the late season, 10 orders, 24 families and 39 insect species were encountered. Heteroptera had the highest species (11) with 28.2% relative abundance, while thysonoptera and dermaptera, 1 species each with relative abundance of 2.6% were the least. Ootheca mutabilis Sahl, Aphis craccivora Koch, Megalurothrips sjostedti Trybom, Maruca vitrata Fab and coreid bugs such as Cravigralla tomentosicollis Stal, Anoplocnemis curvipes Fab, C. shadabi, Aspavia armigara Fab, Nezara virudula L, Mirperus jaculus were the commonest major insect pests on cowpea at Asaba. There were more insect species in the early than late season in the study area.
Key Words : Cowpea, insect pests, early/late seasons, Asaba, southern Nigeria.
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