Leveraging location intelligence and individual-based modeling to simulate Rhipicephalus microplus infestation and eradication dynamics at the cattle-wildlife interface

Abstract

Cattle fever ticks (CFT), Rhipicephalus (Boophilus) annulatus and R. (B.) microplus, threaten the economic security of the USA cattle industry as vectors of Babesia bigemina and B. bovis. Of the two CFT, R. microplus has a more invasive biology and thrives in tropical and subtropical ecosystems. The U.S. Cattle Fever Tick Eradication Program successfully eliminated CFT from the southern USA and has since prevented CFT re-establishment by operating surveillance and quarantine in South Texas, including the permanent quarantine zone along the Texas-Mexico border. However, introductions and successful establishment of alternate CFT hosts, including white-tailed deer (Odocoileus virginianus) and nilgai (Boselaphus tragocamelus) in the Tamaulipan biome, have complicated eradication efforts. We used location intelligence and a spatially explicit, individual-based model to simulate potential impacts of wildlife hosts on R. microplus infestation/eradication dynamics in the Laguna Atascosa National Wildlife Refuge that encompasses a brushland ecosystem with diverse coastal habitats, including parts of a lagoon in South Texas. Results of our hypothetical eradication scenarios suggest that even sparse populations of wildlife hosts can maintain R. microplus populations in habitat-specific refugia during eradication efforts. The present model version is the first to have incorporated a georeferenced representation of a real landscape and to have integrated site-specific field data on climatic conditions and cattle movement patterns. Model forecasts of spatially explicit chronologies of changes in R. microplus densities can aid in a priori evaluation of field sampling strategies and treatment applications in specific landscapes under specific environmental conditions.