Comparative Efficacy of Three Bio-insecticides and a Synthetic Insecticide in Controlling Insect Pests of Cowpea (Vigna unguiculata -L. Walp.) in Vola, Nigeria.

Abstract

Field experiments were conducted during the 2008 and 2009 cropping seasons at the Teaching and Research Farm of the Federal University of Technology, Yola, to compare the efficacy of three selected plant extracts and cypermethrin (decis) in the Control of insect pests of cowpea (Vigna unguiculata L. Walp) . The experiment was laid out in randomized complete block design (RCBD) replicated four times. The treatments included aqueous extracts of Tomato (5% concentration), Basil and Tobacco (3.3% concentration), cypermethrin (6.6 concentration, a synthetic pyrethroid) 10 EC at 0.8 I ha’ and an untreated control. The leaf of selected plants were crushed and pounded, then soaked overnight at 50 g, 33.3 g and 66.7 g of pounded mass per liter of water for tomato, basil and tobacco, respectively. The extracts were sprayed at 12, 14 and 16 weeks after sowing (WAS). Results show that over the two years, plots treated with plant extracts were similar in the number of infesting insects (0.75-2.75), leaf damage (0.6- 1.0), percentage pod damage (17.3-24.4%). These were comparable to number of insects (1.63), leaf damage (0.5), pod damage (15.9%) in cypermethrin treated plots, but significantly different from untreated check. Over the two years, grain yields in all the treated plots were significantly higher than yield recorded in the control (324.8 kg ha-1). It was concluded that all the tested plant extracts have potential to substitute synthetic insecticides for control of insect pests of cowpea.