BACKGROUND : Due to the development of resistance to synthetic insecticides, adverse effects to human health,
non-target organisms and the environment, there is an urgent need to develop new insecticides, which are
effective, safe, biodegrable and target-specific. This study was undertaken to evaluate the adulticidal activity of
10 plants used traditionally as mosquito repellents in South Africa.
METHODS : The dried plant materials were extracted with dichloromethane (DCM) and ethanol (EtOH). The extracts
were evaluated for adulticidal activity against Anopheles arabiensis mosquitoes, a potent malaria vector in South
Africa. Adult mortality was observed after 24 hours of exposure.
RESULTS : All the extracts showed adulticidal activity. The highest activity was observed in both DCM and EtOH
extracts of Aloe ferox leaves with 98 and 86% mosquito mortality, respectively. The DCM extract of A. ferox leaves
was then subjected to a dose-dependent bioassay to determine the EC50 value. The extract exhibited an EC50 value
of 4.92 mg/ml.
CONCLUSION : The results of the present study showed that the DCM extract of A. ferox leaves may have the
potential to be used as an insecticide against An. arabiensis. Further studies to isolate and identify active
compounds are in progress.