Invasive wineberry influences tick-borne disease dynamics across spatial scales

In recent decades, increased incidences of tick-borne diseases, including Lyme disease (Borrelia burgdorferi), Anaplasmosis (Anaplasma phagocytophilum), and Babesiosis (Babesia microti) have occurred in urban areas. The prevalence of the pathogens causing these diseases relies on a complex set of interactions between the tick vector (Ixodes scapularis) and its prominent hosts, white-tailed deer (Odocoileus virginianus) and white-footed mice (Peromyscus leucopus). Additionally, predators of small mammal hosts, such as red fox (vulpes) may influence host-tick interactions. While urbanization alters these interactions at the landscape scale, localized factors such as invasive vegetation may have additional impacts within forest plots and at the microhabitat scale. In this study, we sought to understand the impacts of urbanization and the presence and structure of the invasive understory shrub, wineberry (Rubus phoenicolasius), on tick-borne disease dynamics in southeastern Pennsylvania. We employed a hierarchical field study at three scales to understand the scale at which urbanization and wineberry presence, or the dense vegetation structure it creates, impacts hosts, ticks, and pathogens. At the microhabitat scale, we found increased small mammal activity, which likely played an indirect role in increasing B. microti and A. phagocytophilum prevalence at the same scale. However, tick abundance and general pathogen prevalence were not concentrated at the micro-habitat scale, but instead were higher in invaded plots as a whole. Our results suggest that invasive shrubs aggregate ticks and tick hosts, leading to increased pathogen prevalence, but that pathogen risk may vary across scales. These findings have important implications for invasive vegetation and tick-borne disease management.