Abstract

Post-harvest pests are known to cause severe losses of beans in particular the bean weevil, Acanthoscelides obtectus, necessitating immediate and long term control measures. Convectional pesticides have been used for decades to protect stored grain from pests, but their harmful environmental impact and pest resistance resulting from the need for increased pesticide use have triggered researchers to search for eco-friendly, biodegradable and potent biopesticides. The use of natural products derived from metabolic activity of plants may constitute a new avenue of pest control. This paper describes phytochemical and biological investigations of leaves, root, and stem bark crude extracts and isolated compounds of selected Kenyan plants used to control the bean weevil. Bioassays tests of the compounds were done against brine shrimp to test their insecticidal activity against the bean weevil. Antibacterial and antifungal activity of the crude extracts of S. didymobotrya was also done. The extracts of S. didymobotrya showed high toxicity as well as adulticidal activity against bean weevil.

Key words: Biopesticides, Postharvest, Senna didymobotrya, Acanthoscelides obtectus.