Field evaluation of Cowpea (<i>Vigna unguiculata</i> (L.) Walp) varieties for resistance to some major insect pests in Ago-Iwoye, South west Nigeria

Abstract

Field trials to screen twelve varieties of cowpea for resistance to major insect pests were conducted over two planting seasons (2002 and 2003) at the Teaching and Research Farm of the College of Agricultural Sciences, Olabisi Onabanjo University, Ago-Iwoye. Results showed that varietal resistance to insect pests in cowpea varied with growth stages and seasonal changes. Five major insect pests (Aphis craccivora, Megalurothrips sjostedti, Maruca vitrata, Riptortus dentipes and Clavigralla tomentosicollis) were observed at the various stages of growth of cowpea plant. Results suggest that the cowpea variety IT90K-277-2 was resistant to Aphis craccivora while IT86D-719 was resistant to Megalurothrips sjostedti. Maruca vitrata did not pose any threat to most of the cowpea varieties tested. IT95M-118, IT86D-719, IT95M-120 and IT95M-220 were resistant to Riptortus dentipes, a pod-sucking pest. The pod evaluation index showed that IT95M-118 and IT84E-124 were resistant to pod sucking insects. The highest pod and peduncle damage were recorded on variety IT95M-120. 

Keywords: Cowpea; Major Insect pests; Resistance