Phytochemical investigations of Piper guineense seed extract and their effects on Sitophilus zeamais (Coleoptera: Curculionidae) on stored maize

Three different solvents namely; hexane, ethyl acetate and ethanol were used in partitioning the extracts obtained from Piper guineense seeds and solvent extracts were investigated for the presence or absence of secondary metabolites. Extracts were further evaluated on adult maize weevils, Sitophilus zeamais. Experiment was carried out under laboratory conditions at 27 ± 2 °C ambient temperatures and 65 ± 5% relative humidity and was arranged in a completely randomised design in four replicates. Parameters assessed, including contact toxicity, repellent effects as well as effect of solvent extracts on the germination of maize seeds. Results obtained showed that the solvent extracts contained all the secondary metabolites tested except flavonoids and steroids. As well, all the solvent extracts were lethal and possessed high repellent action against S. zeamais, with ethanol fraction being the most potent. There was no significant difference in the germination of seeds treated with the solvent extracts as well as the ethanol control. The results obtained from this study reveal P. guineese as a potential candidate for bio insecticide and could serve as an alternative to synthetic insecticides.