Exploring the effects of pathogen infection on tick behaviour from individuals to populations

Abstract

Ticks vector a greater variety of pathogens than any other arthropod group, making them a significant threat to the public, companion animals and wildlife. Surveying wildlife habitats and areas commonly used for recreation for the presence of ticks and the pathogens that they carry is essential to the prevention of tick-borne diseases. Tick behaviour also plays an active role in transmission dynamics. We set out to study the host-seeking behaviour of Amblyomma americanum , the lone star tick, at the population level and at the individual level by collecting ticks in public parks in Gainesville, Florida, U.S.A., and by conducting behavioural assays on host-seeking behaviour (questing). We assayed a subset of the collected ticks for 3 consecutive days to determine whether ticks displayed repeatable, individual level differences in questing behaviour. Afterward, we screened ticks for two human pathogens, Rickettsia spp. and Ehrlichia spp. While we did not find differences in pathogen prevalence among the populations, we found that nymphal ticks infected with Rickettsia amblyommatis spent less time questing than uninfected nymphs. However, across all populations, we found a greater prevalence of R. amblyommatis in adult ticks. Additionally, nymphs were more likely to engage in questing behaviours than adults. Lastly, we found significant repeatability in the average height that a tick quests and the questing likelihood of a tick. These findings could fill a gap in the knowledge about trends in disease dynamics. • Ticks displayed repeatability in average heights quested and the likelihood to quest. • Infected nymphal ticks spent less time questing than uninfected nymphs. • Nymphs were more likely to engage in questing behaviours than adult ticks. • Ticks from rural sites quested higher on average compared to ticks from city parks.