Department of Environmental Biology and Fisheries, Faculty of Science, Adekunle Ajasin University, PMB 001, Akungba Akoko, Ondo State, Nigeria.

 Powders from Vernonia amygdalina were evaluated for their efficacy as contact insecticides on cowpea bruchid, Callosobruchus maculatus in the laboratory at temperature of 30±2^oC and 75±5% relative humidity. The powders were applied at rate 2g/20g of cowpea seeds. The result showed that the plant powders tested as contact insecticides significantly (P<0.05) reduced the number of adults bruchid. However, leaf of V. amygdalina was the most toxic to C. maculatus that evoked 100% mortality of adult cowpea bruchid after 72 hours of exposure. There was no progeny development of the bruchid in samples treated with V. amygdalina. The survival of the bruchid from eggs to adults treated with the plant part powders showed that there was significantly (P<0.05) more % progeny development in the control compared to treated ones. This study showed that all the tested plant parts powders were toxic to cowpea bruchid and the powders can be mixed with cowpea seeds to prevent hatching of the eggs thereby helping in their management. From the study, the order of effectiveness of the plant powders could be ranked thus; Leaf>stem bark>root. Bitter leaf can be used as entomotoxicant against C. maculatus and its incorporation into traditional storage pest management is strongly recommended in developing countries.

Keyword: Beetle Perforation Index, Callosobruchus maculates, Entomotoxicant, Vernonia amygdalina