Insecticidal Potential of Eucalyptus citriodora Hook and Hyptis suavolens (L.) Poit Ethanol Leaves Extracts against Malaria Mosquito (Anopheles gambiae Giles)

Abstract

Adult mosquitoes are known to transmit diseases, including malaria and filariasis. The larvicidal, pupacidal and mosquitocidal properties of the leaves ethanol extracts of E. citriodora and H. suaveolens against the larva, pupa and adult Anopheles gambiae were examined. Phytochemical screening was also conducted on the selected plant species to determine the secondary metabolites. Ethanol was the solvent used for the extraction of the leaves using Soxhlet extractor at 60oC to determine the secondary metabolites. The larvae, pupa and adult mosquito were exposed to 0.2, 0.4, 0.6, 0.8 and 1.0% of the extract at 28 ± 2oC, 75 ± 5% RH, 12L:12D photoperiod. Results showed that the leaves extracts of both plants caused high mortality of larvae, pupae and adults of An. gambiae at 1.0% concentration level. The most effective extract was H. suaveolens which caused 100 % mortality of larvae and pupae at 1.0% concentration level within 48 h, while 100% mortality of adult An. gambiae was observed at 1.0% concentration within 4 h. Results also showed that E. citriodora leaves contains saponins, tannins, flavonoid, phenol, quinones and alkaloids, while that of H. suaveolens leaves contains saponins, tannins, flavonoid, phenol, alkaloids and sterols. As the extracts of both plants caused mortality at every stage of An gambiae, it can be suggested that the two plants could be integrated into vector control program of malaria and filariasis.