Journal of Vector Borne Diseases (Mar 2010)
Preliminary study on mosquito repellent and mosquitocidal activities of Ocimum gratissimum (L.) grown in eastern Nigeria
Abstract
Background & objectives: The study examined the mosquito-repellent and mosquitocidal activitiesof the volatile oil of Ocimum gratissimum at three different locations (World Bank Estate, Ihitteand Umuekunne) in Imo State, eastern Nigeria, with the purpose of sourcing for mosquito repellentthat is cheap, abundant, environment and user-friendly.Methods: Four different lotions; 20% (v/v) and 30% (v/v) concentrations each of the extractedvolatile oil in two natural oil bases (olive and palm kernel) were made and six volunteered humanbaits were used to evaluate the mosquito repellent and mosquitocidal activities of the stock materialsat the three different centres from September to November 2008.Results: Topical application of each of the four different lotions significantly (p <0.05) reduced thebiting rate of mosquitoes in all the three locations tested. The 30% (v/v) concentration in olive oilbase exhibiting highest average percentage repellencies of 97.2, 95.7 and 96.3% at World BankEstate, Ihitte and Umuekunne centres respectively while the 20% (v/v) concentration in palmkernel oil base had the least repellency of 36.3, 41.6 and 36.3%, respectively. The other twoformulations had values ranging from 67.8 to 80% in the three locations. The 30% (v/v)concentration in both olive and palm kernel oil bases afforded all night protection against mosquitobites in all the centres, and demonstrated fast knockdown and paralyzing effect on few mosquitoesat the urban centre (World Bank Estate).Interpretation & conclusion: The study confirms that O. gratissimum grown in eastern Nigeriahas mosquito-repellent and mosquitocidal potentials and the formulations could be used to reducehuman-mosquito contacts and hence mosquito-borne diseases and irritations caused by their bites.
