Evaluation of larvicidal and repellent activity of Juniperus procera essential oil against anopheles arabiensis, In Ethiopia

Abstract

Background: Despite of several decades of control efforts still malaria is considered to be a major public health issue and nearly half of the world population at risk of malaria. Malaria is a major public health problem in Ethiopia. Objective The aim of this study was to evaluate the larvicidal and repellent activity of Juniperus procera essential oil against Anopheles arabiensis, which is major malaria vector in Ethiopia. Method: Experimental study was conducted from June to November 2012, essential oil from Juniperus procera leaves were obtained by hydro-distillation method. The mosquito larvicidal and repellent efficacy were evaluated by using WHO standard procedure in Adama malaria research center under the laboratory conditions, the field study has been carried out by using An. gambiae sensu lato larvae ,from Boye river in Jimma town. Results were analyzed using of probit analysis, SPSS statistical software, Ms Excel 2007 and Repellency calculation. Results: The results showed that essential oil of J. procera exhibited significant larval mortality against An. arabiensis. However, the highest larvicidal activity was observed and the LC50 and LC90 values were 14.4 and 24.7 ppm and 24.5 and 36.2 ppm for laboratory and field conditions, respectively. The Chi-square value of laboratory and field 6.662 and 4.622 are respectively, and significant at the P<0.05 level. The results clearly suggest that the laboratory reared mosquito larvae were more susceptible than field collected anopheles larvae. The essential oil showed significant repellency against adult An. arabiensis. Among the different (0.1, 0.15, 0.25 and 0.5 ml/cm2) concentration of essential oil tested for the repellent activity and the largest protection time330 min was observed in 0.5 ml/cm2. All the four tested concentrations of J. procera essential oil offered significant protection and independent t test results shows statistically significant (p value=0.0001) [0.1 ml/cm2 (t=82.7; df=4); 0.15 ml/cm2 (t=80.3; df=4); 0.25 ml/cm2 (t=25.3; df=4); 0.5 ml/cm2 (t=96.8; df=4)] difference between treated and control groups. Overall, both the larvicidal and repellent activities were dose dependent. Conclusion: J. procera essential oil showed promising larvicidal and repellent properties against An. arabiensis and it could serve as a natural larvicidal and repellent agent. However, the active principles as well as mode of action must be identified in future studies.