D3400: Creepers on the lurk: Questing activity and preference by off-host tick nymphs and adults (Acari: Ixodidae) in different vegetation and habitats

In Canada tickborne diseases are on a dramatic rise. Here, two tick species are of particular medical importance for humans, livestock and pets: the blacklegged tick, Ixodes scapularis, infamous for the transmission of Borrelia burgdorferi, the causative agent of Lyme disease. In addition, the American dog tick Dermacentor variabilis, is an important vector of Rickettsia rickettsia which is the pathogen behind Rocky Mountain Spotted Fever. Presence, abundance, and activity of tick species are known to depend on vegetation, temperature, and relative humidity. However, little is known about (innate) vegetation and plant preference of ticks during questing behaviour in which they seek a bloodmeal by ascending onto plants, extending their front legs, and waiting to attach to a passing host. Over the course of co-evolution with their hosts, ticks may have evolved to frequent vegetation associated with these hosts during their bloodmeal-seeking behaviours. We hypothesized that the two primary factors influencing vegetation attraction and avoidance are the microclimate provided and semiochemicals emitted by the plants. We have sampled sites across Nova Scotia (Canada) with variation in vegetation type, leaf litter and degrees of human population density and recorded tick presence. Plant species that consistently overlapped with tick presence were tested for their headspace composition (GC-MS). Moreover, plants were analyzed for their behavioural activity in wind tunnel as well as petri dish arena assays and electrophysiological recordings (GC-EAD) were conducted. Finally, candidate plant species which affected tick behaviour in laboratory assays were studied under semi-field conditions.