Effects of Cymbopogon citratus (lemon grass) and Ocimum suave (wild basil) applied as mixed and individual powders on the eggs laid and emergence of adult Callosobruchus maculatus (cowpea bruchids)

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.