ABSTRACT
The insecticidal effects of Piper guineense and Pirimiphos-methyl was evaluated on cowpea. The treatments used were P. guineenseat 0.2, 0.4, 0.6, 0.8, and 1g as well as Pirimiphos-methyl at 0.1g per 20g of cowpea seeds, each laid out in Complete Randomized Design (CRD) in the laboratory. Results indicated that P. guineense at 1g concentration significantly (P<0.05) reduced the oviposition potential, egg hatching rate, holes and emergence of adults Callosobruchusmaculatus. The powders caused chronic toxicity and inhibit development. The efficacy in respect of toxicity exhibited significant effect from 0.2g treatment of Piper guineense at 24hrs, 48hrs, 3 days, and 7 days after infestation, and highest at 1.0g Piperguineense. The efficacy in respect of toxicity also exhibited significant effect at 0.1g treatment of Pirimiphos-methyl. All the responses were found to be concentration dependent during the course of the study.