Efficacy of Four Species of Zingiberaceae Extract Against Vectors of Dengue, Chikungunya and Filariasis.

Laboratory bioassays on insecticidal activity of hexane crude extract derived from four species of Zingiber: Zingiber officinale var. rubrum (HZOR), Zingiber montanum (HZM), Zingiber spectabile (HZS) and Zingiber zerumbet (HZZ) were carried out against three mosquito larvae vector: Ae. albopictus, Ae. aegypti, and Cx. quinquefasciatus. GC/MS analysis revealed 43, 82, 50, and 51 compounds from HZO, HZM, HZS, and HZZ, respectively. The major principal constituents found in HZO extract were zingerone (14.92%) and benzaldehyde dimethyl thiol acetal (11.61%); HZM extract were dimethyl 4-methylphthalate (12.64%) and carbendazim (12.62%); HZS extract had 1,1'-ethylenebisdecalin (42.52%) and 1- pentadecyne (11.5%); and HZZ extract were humulene epoxide II (20.84%) and zerumbone (60.4%). Assessment of larvicidal efficacy demonstrated good larvicide effects towards all the crude hexanes. The mortality was observed after 24h exposure. The highest larvicidal mortality of Ae. albopictus larvae was found in HZOR, HZM, and HZS (LC50= 96.86, 99.04 and 93.35 mg/L; LC90= 168.65, 153.77, and 168.65 mg/L) respectively. HZM and HZZ were effective against Ae. aegypti larvae with LC50= 84.95 and 82.05 mg/L and LC90= 134.85 and 121.05 mg/ L, respectively. HZZ showed the most effective extract against Cx. quinquefasciatus larvae with LC50= 49.28 mg/L and LC90= 83.87 mg/L. No mortality was recorded in the control. Results from studies suggest that bioassay-guided effective extracts of Z. officinale var. rubrum, Z. montanum, Z. spectabile and Z. zerumbet are potential larvicidal candidates for controlling Ae. albopictus, Ae. aegypti, and Cx. quinquefasciatus.