The spread of blacklegged ticks (Ixodes scapularis) and growing threat of Lyme disease transmission has increased demand for effective, safe and environmentally friendly repellent products. Plant-derived essential oils are natural products that exhibit insecticidal and repellant activities and represent a promising alternative to synthetic repellants. However, mechanisms by which ticks detect odor stimuli and how such stimuli may function as repellents are not well understood. We examined the repellent activity of selected essential oil components towards I. scapularis in short- and long-term dose-response trials. To determine the specific olfactory organs involved in detection of chemical stimuli, we tested tick behavioral response in repellency bioassays after removing appendages that house chemosensory sensilla (e.g., foretarsi or pedipalps). New prototype formulae were tested in longevity trials repelling up to 95% of tested ticks after 1 h post-application. This study provides new insight regarding tick olfaction and behavior, and innovative methods for selecting appropriate chemicals for development of novel plant-based repellent products for protection from ticks.
Keywords: Essential oils; Haller’s organ; Palps; Repellent; Terpenoids; Tick olfaction.