Abstract

It has been estimated that over 90% cowpea is lost to cowpea bruchids especiallyCallosobruchus maculatus. A mixture of plant 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 reproductive fitness of F₁generation of 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 F₁ and subsequent F₂ adult that emerged from the untreated combination were compared with the untreated control (0L: 0W). The plant mixture 60L: 40W had the least mean number of egg counts and significantly (P<0.05) suppressed F₂ adult emergence. This plant material mixture had the most knock on effect from the original parent and this shows that it can serve as grain protectants against C. maculatus.

Key words: Cymbopogon citratus, Ocimum suave, Callosobruchus maculatus, F₁, F₂generation adults.