Formulas of components of citronella oil against mosquitoes (Aedes aegypti).

The mosquito Aedes aegypti is an epidemic vector of several diseases such as dengue fever and yellow fever. Several pesticides are used to control the mosquito population. Because of their frequent use, some mosquitoes have developed resistance. In this study, we used the Y-tube olfactometer to test essential oils of Cymbopogon species and screened specific formulas of components as repellents against Ae. aegypti. At 400 µL, the extracted oil of citronella grass (Cymbopogon nardus) and myrcene produced a low-active response by inhibiting mosquito host-seeking activity. Citronella grass, lemon grass (Cymbopogon citratus), citral and myrcene also produced a low-treatment response to repellents, for more potential to affect host-seeking behavior. Furthermore, the mixture of citral, myrcene, and citronellal oil (C:M:Ci = 6:4:1) greatly affected and inhibited host-seeking behavior (76% active response; 26% treatment response with 40 µL; 42.5%, 18% with 400 µL; and 19%, 23% with 1000 µL). As compared with the result for N,N-diethyl-3-methylbenzamide (DEET; 44%, 22% with 400 µL), adjusting the composition formulas of citronella oil had a synergistic effect, for more effective repellent against Ae. aegypti.