Abstract

Mosquito-borne diseases are the most serious global public health issues, threatening 3.3 billion people. Better control tactics that are safe, less expensive, and more ecologically friendly are being promoted in order to control these vectors. To this end, a study on the insecticidal potential of Ocimum gratissimum and Cymbopogon citratus on female Anopheles mosquito was investigated. Fresh leaves of the plants were sought for and collected locally and were identified in Department of Botany, Federal University of Lafia. The leaves were washed with running tap water and air-dried for three weeks at room temperature. Crude leaf extract preparation was done followed by phytochemical analysis. Five metabolites (phenols, flavoniods, alkaloids, tannins and saponins) were present in the extracts of the two plants except ethanolic extract of C. citratus, which had three metabolites. For the metabolites quantified, O. gratissimum had higher proportion. Perching of mosquito decreased with increase in concentration of the extracts. However, there was no significant difference (P > 0.05) in the cumulative number of mosquito that perched for O. gratissimum aqueous extract, whereas there was a significant variation (P < 0.05) in O. gratissimum ethanolic extract. The cumulative frequency of mosquito that perched in relation to the different concentrations of C. citratus for both extracts showed a significant difference (P < 0.05). There was a significant difference (P < 0.05) between aqueous and ethanolic extracts for each plant extract as well as across concentrations. C. citratus aqueous extract showed higher percentage repellency (86%) at 0.001 mg/ml. Only ethanolic extract of C. citratus at 0.001 mg/ml concentration yielded mortality of 6.67%. The LC₅₀ and LC₉₀ for C. citratus were 0.0000661 mg/ml and 0.0000126 mg/ml respectively. Finally, this study found that the two selected plants exhibit biorepellant properties against malaria vectors.