Larvicidal Activity of Crude Extracts of Vernonia cinerea Less (Asteraceae) against the Larvae of Anopheles gambiae in Bobo Dioulasso, Burkina Faso

Abstract

Aims: This study aims to evaluate the larvicidal activity of lyophilized methanolic extracts, hydro-methanolic extracts and aqueous extracts of Vernonia cinerea Less against the 3rd and 4th instars larvae of Anopheles gambiae. Place and Duration of Study: Pharmacognosy Laboratory, Department of Biomedical Sciences, Centre MURAZ /Research Institute for Health; Ministry of Health, Bobo-Dioulasso, between February 2017 and January 2018. Institut de Recherche en Sciences de la Santé/Direction Régionale de l’Ouest (IRSS) Bobo-Dioulasso, between March 2017 and January 2018. Methodology: The whole plant material was collected in Banfora, located at West of Burkina Faso. The 80% methanolic, 50/50% hydro-methanolic and aqueous extracts were obtained by using the classical natural product extraction method of the laboratory. Extracts were lyophilized and a series of concentrations of the extracts ranging from 0.001 – 100 mg/L were prepared. The larvicidal activity of lyophilized extracts has been tested against the 3rd and 4th Anopheles gambiae larvae. The larval mortality was evaluated after 24 hours and 48 hours of exposure. The percent of means of mortality was calculated. Lethal Concentration LC50 and LC90 values were determined. Results: In the laboratory, the results of methanolic extract at 100 mg/L achieved (100%) mortality against Anopheles gambiae after 24 hours of exposure.The same extract at 10 mg/L generated (95.85±1.26%) of mortality outside the laboratory. The 80% methanolic extract showed Lethal Concentration LC50 of 11.07 mg/L and Lethal Concentration LC90 of 81.38 mg/L (after 24 hours). The 50/50% hydro-methanolic extracts achieved Lethal Concentration LC50 of 22.27 mg/L against 3417.78 mg/L respectively inside and outside of the laboratory. Conclusion: The methanolic extract is the most effective in killing on the larvae compared to the other extracts tested. Vernonia cinerea Less possesses larvicidal activity against Anopheles gambiae larvae. It may be a possible source of mosquito vector control. This study provided promising finding for using crude extracts of Vernonia cinerea Less in controlling larvae of malaria vectors.