GAINESVILLE, Fla. — To protect personnel on Southeastern military installations from tickborne diseases, a federal program has awarded a five-year, $2.45 million grant to a team of researchers with the University of Florida Institute of Food and Agricultural Sciences and other institutions. The grant was provided by the federal Strategic Environmental Research and Development Program, an initiative supported by the U.S. Department of Defense, Department of Energy and the Environmental Protection Agency.
The scientists will determine how tick populations are affected by invasive plants, fire and the availability of host animals in specific locations; this information will help the team assess tickborne disease risk under future climate conditions.
Portions of the project based at UF/IFAS will receive more than $700,000 in funding, said Jack Payne, UF senior vice president for agriculture and natural resources. “This project requires an interdisciplinary approach to account for all of the relevant ecological factors that influence the risk of people being exposed to tickborne diseases,” Payne said. “An ideal team of subject-matter experts has come together here, and I’m proud that UF/IFAS is involved.”
Participating faculty represent UF/IFAS, the University of Illinois at Urbana-Champaign and Boston University, Payne said. Field studies will take place on more than a dozen U.S. Department of Defense properties where the lone star tick is found, including sites in six states where the tick co-exists with an invasive plant known as cogongrass — Alabama, Florida, Georgia, Louisiana, Mississippi and South Carolina. Researchers will also assess Midwestern sites where the tick is present but the invasive plant is not.
The team will conduct three years of field work to assess tick populations, white-tailed deer populations, plant communities, plant invasions, and pathogen presence in ticks, said Jackie Burns, UF/IFAS dean for research and director of the Florida Agricultural Experiment Station. Two years of data analysis will follow, she said, with researchers using models to develop disease-exposure risk maps for future time frames and climate conditions, as well as early-warning systems and management guidelines.
“This is an extremely well thought-out approach,” Burns said. “To my knowledge, this project is the first attempt to assess tickborne disease risk by examining a suite of environmental factors that are critical to the tick’s life cycle and tickborne disease epidemiology in nature.”
The effort focuses on the lone star tick, Amblyomma americanum, because it is the most significant disease vector among Southeastern ticks, Burns said. In the Southeast, this species is known to carry pathogens responsible for human monocytic ehrlichiosis, often known simply as ehrlichiosis, and tularemia, also known as rabbit fever.
Plant ecologist Luke Flory, a co-principal investigator and an associate professor with the UF/IFAS agronomy department, will oversee a team of researchers from UF who will survey plant communities, collect ticks, evaluate fire effects, and document white-tailed deer abundance across the study sites.
The fieldwork will include a focus on cogongrass, an invasive plant native to East Asia that was imported to the U.S. in the early 20th Century. Cogongrass is now found on more than 2.5 million acres in the Southeast, Flory said, with a range that extends throughout Florida and Alabama to portions of Texas, Arkansas, Tennessee and North Carolina.
Cogongrass is known to alter fire regimes and plant communities where it invades, because those areas burn hotter than areas dominated by native plants and the invader can quickly recover from most fires, he said. Fires fueled by dense stands of cogongrass may suppress native plants, creating opportunities for cogongrass to invade new areas.
“For that same reason, plant invasions can also force changes in the way land managers carry out prescribed fires,” Flory said. “Periodic fire is a natural and necessary feature of upland environments in the Southeast, whether it’s wildfire or prescribed fire. When cogongrass invades, it can directly affect native plants and wildlife, and further threaten organisms that can’t survive the more intense, prolonged heat of a cogongrass-fueled fire.”
The team’s working hypothesis is that the combined effects of altered plant communities and more intense fire events will influence wildlife distribution and abundance, with direct and indirect effects on tick populations.
“Plant invasions may periodically reduce populations of the lone star tick, if the ticks are unable to survive fire events involving cogongrass,” Flory said. “But many factors are involved — it could turn out that the environmental conditions created by invasions independent of fire will benefit ticks, that wildlife such as deer that host ticks favor invaded areas, or that cogongrass has a range of effects that vary over time, or from one habitat to another.”
The research team includes disease ecologist Brian Allan, the project’s principal investigator and an associate professor with the University of Illinois at Urbana-Champaign, and ecosystem modeling expert Michael Dietze, a co-principal investigator and an associate professor with Boston University.
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By: Tom Nordlie, 352-273-3567, tnordlie@ufl.edu
The mission of the University of Florida Institute of Food and Agricultural Sciences is to develop knowledge relevant to agricultural, human and natural resources and to make that knowledge available to sustain and enhance the quality of human life. With more than a dozen research facilities, 67 county Extension offices, and award-winning students and faculty in the UF College of Agricultural and Life Sciences, UF/IFAS works to bring science-based solutions to the state’s agricultural and natural resources industries, and all Florida residents. Visit the UF/IFAS web site at ifas.ufl.edu and follow us on social media at @UF_IFAS.
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