Toxicity of Powders from Indigenous Plants Against Sitophilus zeamais Motsch on Stored Maize Grains
An admixture of powders from Erythrophleum guineense (stem bark and leaf), Aloe vera (leaf) and Dacryodes edulis (seed) were separately treated at three different rates (0, 10 and 20% w/w) on stored maize grains and tested against the maize weevil, Sitophilus zeamais Motsch under laboratory conditions for three months. Pirimiphos methyl (2% dust) used as synthetic insecticide check was applied at 0, 1 and 2% (w/w). Some parameters considered included, mortality (at 24, 48, 72 and 96 h), progeny development (F1 and F2) and grain damage. The results showed that E. guineense stem-bark and A. vera leaf powders applied at 20% (w/w) were more toxic to S. zeamais and could suppress progeny development of the weevil as well as protect maize grains from pest damage compared to D. edulis seed powder and the untreated check. Pirimiphos methyl caused more weevil mortality (p<0.05) within 72 h, considerably suppressed progeny development and reduced grain damage compared to plant powders but its values on the last two parameters were not statistically superior to E. guineense stem bark powder. This technology is simple, cheap, readily available, non toxic to mammals and environmentally friendly. E. guineense plant could add to the lexicon of plant materials known to possess insecticidal attributes for integrated pest management for small-scale rural grain storage programmes in developing countries.
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