Evaluation of Insecticidal Potentials of Five Botanical Powders Against Cowpea Weevil(callosobruchus Maculatus)

ABSTRACT Cowpea (Vigna unguiculata L. Walp.), is one of the most important leguminous crops widely cultivated throughout the tropics, especially in the savanna regions of the world. However, its seed is attacked by several insect pests both in the field and in storage, especially the cowpea weevil. To control weevils, most farmers have adopted the use of chemical insecticides, but these insecticides come with health and environmental problems, and as a result, there is advocacy for the use of bio-pesticides in the form of plant botanicals. This research was done in Agricultural Technology Laboratory of Federal Polytechnic Nekede, Imo State, to investigate the effects of Dennettia tripetala , Moringa oleifera , Chromolaena odorata ,Vernonia amygdalina, and Citrus limon powdered extracts in the control of Callosobruchus maculatus pest of stored Cowpea ( Vigna unguiculata) between August and October 2023 using Completely Randomised Design (CRD). There were six treatments replicated four times. Fifty (50) adult Callosobruchus maculatus were introduced to 100 gram powdery leaves extracts of each bio pesticide in the petri dish. The experiment lasted for 12 weeks to check the incidence and spread of the weevil pest . Data collected were subjected for analysis of variance ( ANOVA ) at 5% probability levels . The mean number of mortality, longevity of weevil , number of рunctures (holes) on cowpea seeds and weight loss of Cowpea seeds were determined. Extracts powder of the selected plant were effective against Callosobruchus maculatus in all parameters tested. The highest mortality of weevil was observed in Moringa oleifera (43), while Control had zero mortality activity . The moringa oleifera leaf powder extract reduced the mean population (50) introduced to 7 ( mean number alive) of Callosobruchus maculatus when compared to Citrus limon extract (11), Dennettia tripetala (14), Vernonia amygdalina (18) and Chromolaena odorata (21). The research recommends Moringa oleifera leaf powder extracts for the prevention and control of stored weevil pests of cowpea seeds.