Bioefficacy of local Lantana camara (Verberneae) plant extracts against the 3rd instar larva and adult stages of Anopheles gambiae senso lato (Giles).

Abstract

Resistance of malaria vectors to synthetic chemicals with high operational cost and environmental pollution has been a great challenge to scientists. Alternative approaches such as the use of natural plant products which are environmentally friendly are put in place to control malaria vectors. This study was focused on testing the effectiveness of three solvent extracts of Lantana camara on the 3^rd instar larvae and adults of Anopheles gambiae s. l. These extracts were obtained by maceration. Bioassays test were carried out by WHO’s method for determination of larvicidal and adulticidal efficacy. The results show that, larval mortality increased significantly with the concentration and exposure time. Lethal concentrations 50 (LC₅₀) and 95 (LC₉₅) after 24 hours of larvae exposure time are respectively 0.31 g/mL and 1.53 g/mL  while within 48 h they are 0.27 g/mL and 0.79 g/mL for hexane extract; 1.45 g/mL and 2.0 g/mL (24 h exposure), 0.84 g/mL and 1.55 g/mL (48 h exposure) for acetone extract; 1.96 g/mL and no lethal concentration causing 95% mortality was determined; 0.40 g/mL and 2.20 g/mL (48 h) for aqueous extract. The efficacy of hexane and aqueous extract on the adult knock down and mortality were not significant even with the increasing extract concentrations and exposure time whereas with acetone extract,  the adult LC₅₀ after 24 h was 2.4 g/mL but with 95% mortality lethal concentration was not determined. According to the results, hexane extract showed high larvicidal efficacy of An. gambiae and acetone extract showed significant adult mortality. Those two extracts of L. camara can be used to fight against An. gambiae as alternative malaria vector control to replace conventional insecticides.