Insecticide Repellency of Plant Extracts Against Callosobruchus maculatus
Obadofin, A. A.; Fatoba, T. A. and Fatunsin G. F.
Journal Title:Journal of Environmental Issues and Agriculture in Developing Countries
Several plant species were selected as potentially safer substitutes for control of cowpea weevil, Callosobruchus maculatus. The objective of the study was to investigate the insecticidal activity effect (that is, avoidance after contact) of aqueous extracts (crude) of Andrographis paniculata, Chromolaena odorata, Datura stramonium, Senna siamea and Vernonia amygdalina (leaves ) in comparison with a synthetic insecticide (actellic powder) frequently used in treatment of cowpea in store. The phytochemical studies revealed presence of arrays of secondary metabolites such as alkaloids, tannins, flavonoids, saponins, oxalates, glycosides and reducing sugar in the tested plant. Cowpea weevils of a single strain were subjected to free-choice tests with cowpea seed sprayed with the different aqueous extracts and actellic powder. The behavioral response of C. maculatus to aqueous extracts and actellic powder differed (p<0.05) from the negative control. The results observed that insecticidal activities were demonstrated as Datura stramonium > Senna siamea > Andrographis paniculata> Chromolaena odorata > Vernonia amygdalina with the synthetic insecticide powder and D. stramonium produced the best result. The aqueous extracts of these plants could be employed in developing natural pest control products that may replace the synthetic bio-pesticides that are currently used against C. maculatus.