COS 234-3 - CANCELLED - Current and future habitat suitability models for four ticks of medical concern in Illinois, USA

Abstract: The greater U.S. Midwest is on the leading edge of tick and tick-borne disease (TBD) expansion, with tick and TBD encroachment into Illinois occurring from both the northern and the southern regions. To assess historical and future habitat suitability of four ticks of medical concern within the state, we fit individual and mean-weighted ensemble species distribution models for Ixodes scapularis, Amblyomma americanum, Dermacentor variabilis, and a newly invading species, Amblyomma maculatum using a variety of landscape and mean climate variables for the periods of 1970-2000, 2041-2060, and 2061-2080. Ensemble model projections for the historical climate were consistent with known distributions of each species but predicted the habitat suitability of A. maculatum to be much greater throughout Illinois than what known distributions demonstrate. Presence of forest and wetlands were the most important landcover classes predicting occurrence of all tick species. Occurrence of Amblyomma americanum was significantly associated with suitable habitat for white-tailed deer (Odocoileus virginianus) within the state, fitting with the ecology of this species. As the climate warmed, the expected distribution of all species were strongly responsive to precipitation and temperature variables, particularly precipitation of the warmest quarter and mean diurnal range, as well as proximity to forest cover and water sources. The suitable habitat for all species was predicted to shrink in the 2050 climate scenario, and then increase more broadly statewide in the 2070 scenario, but at reduced likelihoods. Major population centers like the Chicago Metropolitan Statistical Area remained at high risk of exposure to these vectors across all three climate periods. Predicting where ticks may invade and concentrate as the climate changes will be important to anticipate, prevent, and treat TBD in Illinois.