Several previous studies have
demonstrated that essential oils obtained by steam distillation from
Ocimum basilicum and O. gratissimum in Guinea produced 80% and 70%
mortality against newly emerged adults of the beetle Callosobruchus
maculatus (F.) following exposure to 12 h of fumigation (Kéita et al.,
2001). In addition, the cumulative percentage mortality of S. zeamais
adults on maize grains treated with 0.3% essential oil of O. gratissimum
was 82% after 7 d of treatment (Asawalam et al., 2008). The mortality
of Tribolium confusum adults exposed to coriander oil increases with
concentration and exposure time, and the oviposition deterrent and ovicidal potentials of basil oil against Aedes aegypti females are also dependent on concentration (Khani and Rahdari, 2012; Warikoo et al., 2011).
In this study, two commercialized essential oils (basil and orange oils)
showed strong fumigant and contact activities against S. zeamais and
T. castaneum adults after a 24-h exposure. Basil oil showed particularly
high activity in the fumigant assay, whereas orange oil showed stronger
activity in the contact assay.