Lyme Disease in Canada

Repellent activities of essential oils extracted from sweet fern were evaluated against nymph and adult Ixodes scapularis and Dermacentor variabilis ticks. Essential oils were extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry for qualitative chemical characterization. Eucalyptol (17.9%) and β-caryophyllene (35.3%) were identified as the main components, followed by terpinene-4-ol (5.1%) and γ-terpinene (4.0%). Sweet fern essential oils exerted significant repellent activity towards I. scapularis nymphs, and the response was dose- and time-dependent. In a four-way olfactometer, I. scapularis and D. variabilis adult ticks were offered to choose between a novel tick-attractant mixture and an attractant mixed with the sweet fern essential oil at 1.25% v/v to test the ability of the oil to reduce tick attraction. Approximately 60% (p < 0.01) of ticks selected the attractant mixture; however, when the attractant mixture was offered with the essential oils, the selection of the attractant mixture significantly decreased (2.2-16/7%), indicating that ticks were repelled. Sweet fern essential oils exhibit promising repellent properties against Ixodes ticks and the potential for reducing disease transmission.