Efficacy of Thai herbal essential oils as green repellent against mosquito vectors

Repellency activity of Thai essential oils derived from ylang ylang (Cananga odorata (Lamk.) Hook.f. & Thomson: Annonaceae) and lemongrass (Cymbopogon citratus (DC.) Stapf: Poaceae) were tested against two mosquito vectors, Aedes aegypti (L.) and Culex quinquefasciatus (Say). There were compared with two chemical repellents (DEET 20% w/w; Sketolene Shield(R) and IR3535, ethyl butylacetylaminopropionate 12.5% w/w; Johnson's Baby Clear Lotion Anti-Mosquito(R)). Each herbal repellent was applied in three diluents; coconut oil, soybean oil and olive oil at 0.33 mu l/cm(2) on the forearm of volunteers. All herbal repellent exhibited higher repellent activity than IR3535 12.5% w/w, but lower repellent activity than DEET 20% w/w. The Cananga odorata oil in coconut oil exhibited excellent activity with 98.9% protection from bites of A. aegypti for 88.7 +/- 10.4 min. In addition, Cymbopogon citratus in olive oil showed excellent activity with 98.8% protection from bites of Culex quinquefasciatus for 170.0 +/- 9.0 min. While, DEET 20% w/w gave protection for 155.0 +/- 7.1-182.0 +/- 12.2 min and 98.5% protection from bites of two mosquito species. However, all herbal repellent provided lower repellency activity (97.4-98.9% protection for 10.5-88.7 min) against Aedes aegypti than Culex quinquefasciatus (98.3-99.2% protection for 60-170 min). Our data exhibited that Cananga odorata oil and Cymbopogon citratus oil are suitable to be used as green repellents for mosquito control, which are safe for humans, domestic animals and environmental friendly. (C) 2014 Elsevier B.V. All rights reserved.