Bioactivity of Oils from Medicinal Plants against Immature Stages of Dengue Mosquito Aedes aegypti (Diptera: Culicidae).

To evaluate the efficacy of the essential oils extracted from the branches and leaves of eucalyptus (Eucalyptus globules Labill.), neem (Azadirachta indica A. Juss), peppermint (Mentha piperita L.), basil (Ocimum basilicum L.) and from rhizome of ginger (Zingiber officinale Rosc.) against the larvae and pupae of Aedes aegypti L. The essential oils were extracted with Soxhlet apparatus using petroleum ether as a solvent. The oils were evaluated against 1[sup st], 2[sup nd], 3[sup rd], 4[sup th] instar larvae and the pupae of Ae. aegypti following WHO protocol. The dead individuals in all stages were counted after 8, 16, 24 and 48 hours in treatments of different concentrations (100, 200, 300 and 400 ppm). The percent mortality in each stage was determined and consequently LC[sub 50]s were also calculated by Probit analysis. A control treatment was also run by using petroleum ether in which mortality (<6%) of different life stages of Aedes mosquitoes was observed. Results showed that higher mortality was observed in early life stages than later ones. Ginger was more effective having lowest LC[sub 50] after 8 h (142 ppm) and 16 h (8.5 ppm) against 1[sup st] instar larvae followed by peppermint, basil, eucalyptus and neem. However, eucalyptus and peppermint were efficacious after 24 h (66 and 84 ppm) and 48 h (19.5 and 17 ppm), respectively. Ginger oil showed high efficacy in short period of the time (8 and 16 h) followed by peppermint, basil, eucalyptus and neem, whereas eucalyptus oil exhibited its lethality after 24 h, whilst peppermint has longer potency and persistence (48 h) than other plant oils. For pupal stage, peppermint had knockdown effect (8 h) followed by eucalyptus (16 h), basil (24 h) and neem (48 h). From these results, it can be concluded that the oils of E. globules and M. piperita were effective larvicide against the immature stages of Ae. aegypti. © 2015 Friends Science Publishers [ABSTRACT FROM AUTHOR]