Insecticidal properties of essential oils from Lippia turbinata and Lippia polystachya (Verbenaceae) against Culex quinquefasciatus (Diptera: Culicidae)

Mosquitoes are important vectors of diseases to humans and domestic animals. Chemical control of vectors remains a main resource for the prevention and control of vector-borne diseases. Due to the development of insecticide resistance and risks to human health and the environment of synthetic compounds, the search for alternative pesticides is encouraged. This work assessed the insecticidal activity of essential oils (EOs) from Lippia turbinata and L. polystachya from Argentina on Culex quinquefasciatus mosquitoes. EOs were extracted by hydro-distillation and analyzed with gas-liquid chromatography and mass spectrometry. The insecticidal activity against mosquito larvae, pupae, and adults were evaluated according to World Health Organization protocols. Concentrations ranking from 10 to 160 ppm were assessed at 1, 2, 3, and 24 h posttreatment. The composition of the EO of L. polystachya and L. turbinata were qualitatively similar, with alpha-thujone and carvone as main constituent; differences were mostly due to the proportion of each component. beta-caryophyllene was also an important constituent of the EO of L. turbinata. Both EO were larvicidal at concentrations of 80 ppm or higher, but only L. turbinata was adulticidal. No pupal mortality was detected. The potential of these EOs for vector control is discussed.