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Abstract
The exotic Haemaphysalis longicornis, the Asian longhorned tick, was recently detected in the United States in 2017, however archived specimens indicate that this species has been present in the United States since as early as 2010. At the time of detection, little was known or understood about the natural history of this species and how it would affect human and animal health in the United States presenting many important research questions and knowledge gaps. The central theme for this dissertation is the exotic tick, Haemaphysalis longicornis–its population biology, pathogens, and dispersal. Specific research objectives include: 1) developing a molecular assay to differentiate North American Haemaphysalis species, 2) determining the current host and habitat preferences and distribution within the United States, 3) conducting pathogen surveillance in host-seeking ticks and wild ungulates, and 4) characterizing the genetic structure of Haemaphysalis longicornis populations in the United States. A novel molecular assay was developed to aide in the identification of Haemaphysalis ticks and has been utilized to detect H. longicornis across eight states in the southeastern United States in a variety of habitats (hardwood forests, grassy fields, and manicured lawns) and on a variety of hosts including human, companion animal, livestock, and wildlife indicating that this tick is a habitat and host generalist. These detections resulted in some of the first host, county, and state records for H. longicornis in the United States. Additionally, pathogen surveillance detected a 12.7% prevalence of the exotic piroplasm parasite, Theileria oreintalis Ikeda, in host seeking H. longicornis from Virginia. Finally, using a restriction-site-associated DNA (RAD) sequencing approach to observe nucleotide differences across the genome, we found that native populations of H. longicornis are more diverse than introduced and invasive populations. Additional genetic variation detected within the United Sates suggest that there have been at least five introductory events. Collectively, these studies answer important questions on the natural history of H. longicornis in the United States and what potential impacts it may have for the health of humans and animals.