Using Cold As An Ally: Balsam Fir (Abies Balsamea L., Mill) Needles And Essential Oil Kill Overwintering Ticks (Ixodes Scapularis)

The blacklegged tick, Ixodes scapularis Say, vectors Borrelia burgdorferi , a bacterium that causes Lyme Disease. Although synthetic pesticides can reduce tick numbers, less toxic acaricides would reduce impacts on other animals, such as pollinating insects. Natural-based pest control agents could provide an alternative because they have low environmental persistency; however, natural products struggle to provide effective control. We found a new natural acaricide, balsam fir ( Abies balsamea ) needles, that kill overwintering I. scapularis ticks. We extracted the essential oils from the needles, analyzed their chemical composition, and tested them for acaricidal activity. Both the oil and one of its main components, ß-pinene, kill overwintering ticks. Whole balsam fir needles require several weeks to kill overwintering ticks, while the essential oil is lethal within days at low temperatures (≤4°C). Further, low temperatures increase the efficacy of this low toxicity compound. Higher temperatures (i.e. 20 o C) reduce the acaricidal effectiveness of the essential oil by 50% at 0.1% v/v. Low temperatures may promote the effectiveness of other low toxicity, natural control products. Winter is an overlooked season for tick control and should be explored as a possible time for the application of low toxicity products for successful tick management.