Evaluation of repellent properties of volatile extracts from the Australian native plant Kunzea ambigua against Aedes aegypti (Diptera: Culcidae)

Kunzea arnbigua (Smith) Druce (Myrtaceae) is an Australian native plant, commonly known as tick bush. The essential oil of the plant has been proposed as a potential mosquito repellent. Commercial K. arnbigua oil was analyzed by gas chromatography-mass spectrometry (GC-MS) and its composition compared with that of oils from two individual K. ambigua plants and citronella oil. K. ambigua oils were studied for their repellency against Aedes aegypti L. Formulations of three different K. arnbigua essential oils (30% vol:voi) were tested for repellency to mosquitoes using human volunteers. One oil was compared \vith citronella and N,N' -diethyl-:3-methylhenzamide (deet) for repellency. Oil formulations were also tested for repellency with and without the addition of 5% vanillin. The formulation containing commercially produced K. ambigua oil had a mean complete protection time (CPT) of 49 ± 24 (SD) min. All the K ambigua formulations had comparable repellency to 40% citronella. However, the 60% citronella formulation showed higher repellency than the 40% K. arnbigua formulation. The addition of 5% vanillin did not increase the repeliency of K. arnbigua oi1. Botll K. arnbigua oil and citronella were significantly less repellent than deet. The K arnbigua essential oil formulations should not be advocated for use as repellents in regions prone to mosquito-borne disease.