Mosquito Repellency of Whole Extracts and Volatile oils of Ocimum americanum, Jatropha curcas and Citrus limon

Abstract

The study was carried out to evaluate the efficacies of the crude extracts and of the essential oils from three plants which are used as mosquito repellents. The crude extracts were obtained from the leaves of Ocimum americanum and Jatropha curcas, and from fruit peels of Citrus limon by dry distillation and the volatile oils were isolated from the crude extracts using separating funnels. The mosquito repellency of the crude extracts and of the volatile oils were evaluated using the humanbait technique, whereby hands treated with a pre-determined minimum dose of the repellent were exposed to mosquitoes and the extent of repellency determined, using DEET as standard, revealing that the oils were much more repellent than the crude extracts. The mixtures of crude extracts and the mixtures of volatile oils generally gave higher protection than their respective single repellents. Thus, the components of the different repellents appeared to reinforce each other.