Efficacy of Plant Extracts on Major Insect Pests of Selected Leaf Vegetables in Southwestern Nigeria

Insect pest infestations are perhaps the most important constraint to production of vegetables in Nigeria and one of the primary causes of low quality and yields. Field experiments were conducted at the Teaching and Research Farm of the Federal University of Technology, Akure, in the rainforest zone of Southwestern Nigeria, during the late and early seasons of 2005 and 2006. To evaluate the efficacy of aqueous plant extracts of neem (Azadirachta indica) bark and WestAfrican black pepper (Piper guineese)seeds as a pest control strategy of the selected leaf vegetables viz Amaranthus hybridus L., Celosia argentea L. and Corchorus olitorius L. The selected vegetables were planted as sole and mixed crops. The plots were infested naturally and spraying with aqueous extracts of A. indica, P. guineese and synthetic insecticide, Cymbush commenced at 4 weeks after planting (WAP). Spraying the three selected vegetables under sole and mixed cropping with the aqueous plant extracts at 200 g L 1 significantly reduced the population of the insect pests and their associated damage compared to the control. A. indica extract was more efficacious in protecting the vegetables from insect pest infestation than P. guineense extract. However, the efficacy of A. indica extract was comparable to that of cymbushR.