Efficacy Evaluation of Ocimum gratissimum Stem Extract as Mosquito Repellent

Abstract

Malaria is a mosquito-borne disease which poses a significant threat to human health globally. This research was designed to find out the efficacy evaluation of Ocimum gratissimum stem extract as mosquito repellent. Ocimum gratissimum stems were harvested from different locations within Abuja. Solutions of ethanol (20%), acetone (20%) and aqeous(20%) extracts were prepared and tested on mosquito larvae and adult mosquitoes for repellency and knockdown. Results from this study indicate that 80% of mosquito larvae were killed by ethanol extract, with no mortality recorded for acetone and aqeous extracts. Further more, the ethanol extract repelled 37.5% of mosquitoes while both acetone and aqeous extracts repelled 25% each. All extracts exhibited 0% knockdown on the mosquitoes. Phytochemical investigation revealed that all extract contains flavonoid, phenol and tannin. Higher larvicidal effect was observed in ethanol extractas a result of its ability to extract some potent phytochemicals in higher concentration due to its polarity compared to other solvents. In conclusion, stem extract of Ocimum gratissimum only controlled mosquitoes at the larva stage. It is however recommended that ethanol stem extract of Ocimum gratissimum should be employed in the formulation of larvicide.