Published online by Cambridge University Press: 01 June 2013
Experiments were conducted in the laboratory to screen the leaf extract of Dracaena arborea (Willd.) Link for the presence of chemical groups with insecticidal activity against Sitophilus zeamais (Motsch.) and Callosobruchus maculatus (Fab.). The plant materials were collected, dried, ground to fine powder and extracted with 90% ethanol. Phytochemical screening involved the use of thin layer chromatography analysis for chemical compounds such as alkaloids, tannins, saponins, anthraquinones, flavonoids and terpenes. Partitioning of the extract was carried out by dissolving the extract in water to obtain the aqueous phase, which was partitioned between equal volumes of chloroform, n-hexane, n-butanol and ethyl acetate. The different fractions were screened for insecticidal activity against S. zeamais and C. maculatus. Some fractions of the leaf extract such as ethyl acetate and aqueous fractions demonstrated 100% mortality, offered protection to grains, reduced progeny development and repelled the insects compared with the control. Based on the activity of some fractions, the leaf extract of D.arborea has the potential for development as a botanical insecticide against S. zeamais and C. maculatus.