Species in Vietnam: Essential Oil Compositions and Mosquito Larvicidal Activities.

Essential oils have emerged as viable alternatives to synthetic insecticides for control of mosquito-borne pathogens. The leaf essential oils of eight species of (Lamiaceae) growing in central Vietnam have been obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry. Sesquiterpene hydrocarbons dominated most of the essential oils, with the notable exception of from Ngoc Linh Nature Reserve, which had α-pinene as the major component. Larvicidal activities against have been determined and all of the essential oils showed larvicidal activity with 24-h LC < 65 μg/mL. The leaf essential oils of from Chu Mom Ray National Park and from Ngoc Linh Nature Reserve showed the best larvicidal activities with 24-h LC of 16.8 and 18.0 μg/mL, respectively. The essential oil compositions and larvicidal activities of , , , , and are reported for the first time. Although the larvicidal activities of leaf essential oils are promising, the essential oil yields are relatively low (0.10-0.25%).