Effect of Hexane and Methanol Extracts ofPiper guineense(Schum and Thonn) Seeds against the Larger grain borer (Prostephanus truncatus) in Stored Cassava Chips

Methanolic and hexane extract of black pepper Piper guineense Schum & Thonn was evaluated for its insecticidal property against the larger grain borer Prostephanus truncatus in stored cassava chips. The extracts were applied at various concentrations (4000, 2000, 1000, 500, 250 µ l/ml) with ordinary acetone as control. The experimental setup involved placing ten unsexed adults of the test insect into petri dishes treated with each of the extracts as applicable. Also, cassava chips weighing twenty grams were treated with the different concentrations of the extracts and the control before being artificially infested with Prostephanus truncatus and left for a period of thirty-three days. All of the treatments significantly reduced emergence holes and grain damage compared with the control.