Effect of Plant Extracts on Post Flowering Insect Pests and Grain Yield of Cowpea (Vigna Unguiculata) (L.) Walp.) in Maiduguri, Semi Arid Zone of Nigeria

Abstract

Field experiment was conducted in Maiduguri located in the semi-arid zone of North eastern Nigeria during 2009 and 2010 rainy seasons.The reason for using these plant materials was due to their presence and ease of preparation in the locality. The effect of balanites (Balanites aegyptiaca Del), Momordica balsamina; bitter leaf (Vernonia amygdalina L) and a standard synthetic insecticide cypermethrin 10% EC replicated four times each and sprayed at 10% w/v concentration were investigated on cowpea post flowering insect pests. The experiment was carried out in a randomized complete block design (RCBD). The result obtained showed that balanites leaf and momordica leaf extracts significantly (P < 0.05) reduced the infestation of Maruca vitrata F; Clavigralla tomentosicollis Stal; Anoplonemis curvipes L; Riptortus dentipes F; Mirperus jaculus L and Nezara viridula L.. Pods and Seeds damage were also significantly higher (P < 0.05) reduced by these plant extracts compared to bitter leaf sprayed plots and unsprayed control plots. Undamaged Pods, number of Pods/plants, Pod and Seed weight/plant were significantly (P < 0.05) increased in both plant extracts sprayed plots compared with bitter leaf extracts and control plots. Balanites leaf and Momordica leaf extracts sprayed plots produced significant (P < 0.05) total grain yield per hectare at 7 – days spray intervals. Cypermethrin insecticide gave the overall best results being a systemic and contact acting standard insecticide. Farmers could therefore adopt balanites and Momordica leaf extracts as alternative to synthetic insecticides for optimum cowpea production in Maiduguri.

Key words: Plant extracts, Cypermthrin, Post flowering, insect pests, grain yield, semi arid