Three repellent gels that contain essential oils from local Malaysian plants against dengue vector.

The essential oils of Litsea elliptica, Piper aduncum, and Piper sarmentosum were prepared as repellents in gel formulation, and their repellent properties against Aedes aegypti were experimentally investigated. The lowest effective doses against adult mosquitoes were 0.8%, 0.5%, and 0.4% for Lit. elliptica, P. sarmentosum and P. aduncum, respectively. In laboratory testing with human subjects, all three gels provided over 90.0% repellency at one hour after application and over 80.0% repellency at four hours, compared with 100% and 95.8% protection after one and four hours, respectively, by DEET. In the field, gels with ED concentrations of Lit. elliptica, P. aduncum, and P. sarmentosum essential oils provided 99.3%, 97.5%, and 100% protection, respectively, at two hours. The physical properties and biological stability of the three repellents after storage in hot and cold conditions were also compared. In conclusion, all three gels have the potential for development as repellents against Ae. aegypti.