Abstract

The biological activity of Zanthoxylum xanthoxyloides against Sitophilus zeamais(Coleoptera: Curculionidae) and Callosobruchus maculatus (Coleoptera: Bruchidae) was investigated in the laboratory by admixing leaf, root and bark powders of Z. xanthoxyloides. Methanol extracts of the plant were applied at 2.0 ml per 50 g of grains to assess contact mortality, damage assessment, progeny development and repellent action. The root and bark powders caused 100% mortality of both S. zeamais and C. maculatus while complete protection of grains and progeny inhibition were achieved. Topical application of the extracts caused significant (P<0.01) insect mortality with fresh bark extract offering complete protection of grains and complete inhibition of progeny production by both S. zeamais and C. maculatus. The extracts also evoked moderate repellent effect against the two insect pests. The findings of this study lend credence to the usefulness of yet another biopesticide and its incorporation into traditional storage pest management system is recommended.

Key words: Coleoptera, extracts, pests, powders, progeny, Zanthoxylum.