Effect of Hexane and Methanol Extracts of Piper guineense (Schum and Thonn) Seeds against the Maize Weevil (Sitophilus zeamais) in Stored Maize Grains

Abstract

Methanolic and hexane extract of black pepper Piper guineense Schum & Thonn was evaluated for its insecticidal properties against the maize weevil Sitophilus zeamais Motschulsky in stored maize grains. The extracts were applied at various concentrations (4000, 2000, 1000, 500, 250 µl/ml) with ordinary acetone as control. The experimental setup involved placing ten unsexed adults of each insect species into petri dishes treated with each of the extracts as applicable for the residual treatment application. Also, maize grains weighing twenty grams were treated with the different concentrations of the extracts and the control before being artificially infested with Sitophilus zeamais and left for a period of thirty-three days. All of the treatments significantly reduced emergence holes and grain damage compared with the control.