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.