A detailed analysis of elevation as an impeding factor restricting Ixodes and Dermacentor tick species expansion

A detailed analysis of elevation as an impeding factor restricting Ixodes and Dermacentor tick species expansion
 
 
¹School of Medicine, University of South Carolina, Columbia, SC 29208, USA
²Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA
 
The past two decades have documented increasing range expansions of the American blacklegged tick, Ixodes scapularis, in the North American continent. Despite the regional expansions, this  tick species of public health importance has been infrequently reported in the Appalachian Mountains. We constructed a critical review of the scientific, entomologic, and environmental literature to better understand key factors that might result in these ticks’ inability to adapt and survive in higher elevations. Our detailed analysis identified key abiotic, biotic, macroclimate, and microclimate factors that could explain these species’ poor survival at elevations >1500 feet. Most notably, decreased mean temperature, humidity, and presence of elevated soil pH could explain the failure of this important tick species’ abilities to thrive along the Appalachian mountain range. This information could be used to manipulate environments where these species are encroaching to slow or prevent additional geographic spread and provide insights into tick eco-biology for potential invasive species in the same region.