The influence of deer-targeted tick control interventions on tick distribution

Tick-borne diseases are a significant threat to human health. As a complex, multi-host pathogen system, the effectiveness of host-targeted interventions is difficult to assess fully. One such interaction is the ‘4-posters’ device, which involves topically administering acaricide on white-tailed (the keystone tick host). However, supplementary feeding used in these devices may impact control efficacy by altering deer behavior and intra- and inter-specific interactions. Studies have shown that the core home range of deer shifts towards feeders and high conspecific competition occurs near feeders, along with aggressive behavior and monopolization of feeders by dominant individuals. Such responses can lead to unequal treatment of acaricides among individuals and reduced control efficiency. We used camera trapping methods to assess behavior near the feeders and deer space use in parks where 4-posters have been in operation. Cameras were installed 1) facing 4-poster directly and 2) at successive distances away from the feeders, coupled with an assessment of black-legged tick distribution. We hypothesized that the density of ticks would diminish near the feeders, while the control effect of the device would decrease with distance. We expect that the presence of baits significantly alters the space usage of deer and their interactions, and this serves as a confounding factor that impacts the density of ticks and control effect. The results of this study enhance our mechanistic understanding of the link between bait-based interventions and the resultant control effect by examining the movement and behavior of host species, which will lay the groundwork for developing predictive tools.