Abstract

Post harvest losses of cowpea grain are a serious problem, in Africa, as much as 20 - 50% of grain is lost because of infestation due Callosobruchus maculatus(Cowpea bruchids). Plant mixtures containing Cymbopogon citratus (Lemon grass) (L) and Ocimum suave (Wild basil) (W) powders in the ratios (Lemon grass: Wild basil): 100:0, 80:20, 60:40, 50:50, 40:60, 20:80, 0:100 and 0:0 were used under ambient laboratory conditions with the aim of evaluating the effects of these plant powders on the eggs laid by the adults (Oviposition) and the emergence of F₁ generation of adult C. maculatus (F.) (Cowpea bruchids). The mixed powders were each applied at 1, 2 and 3 g concentration to 20 g of cowpea seeds. Number of eggs laid by the adult bruchids and the emerged F₁ offspring were counted. The mixture 60 L: 40 W had the least mean number of egg counts for the parent bruchids and least number adult F₁ emergence which was significantly (p < 0.05) reduced.

Key words: Cymbopogon citratus, Ocimum suave, Callosobruchus maculatus,oviposition, F₁ generation adults