An invasive grass species found across the globe is posing a new threat, not just to native ecosystems, but to human health. A recent study from the University of Florida (UF) reveals that cogongrass, a notorious invasive plant, is dramatically increasing the survival time of disease-carrying ticks, raising public health risk concerns in the Southeast United States.
Cogongrass Creates a Tick Haven
The research, conducted by UF’s Invasion Science Institute (ISI) and published in the journal Ecology, demonstrated a clear link between the invasive grass and prolonged tick survival. Scientists found that lone star ticks, a species prevalent in the Southeast and known to bite humans, survived over 50% longer in areas dominated by cogongrass compared to native plant communities.
The increase in tick survival is not due to a greater number of hosts like deer. Instead, the dense growth of the invasive grass alters the local environment, creating a favorable microclimate.
“Adult ticks survived over 100 days longer in invaded plant communities compared to native plant-dominated areas, due to changes in the microclimate caused by the invasion,” said Drew Hiatt, the study’s lead author and a graduate student at UF/IFAS.
This dense canopy makes the environment cooler and more humid, conditions that prevent ticks from drying out and dying. Longer survival means ticks have more opportunities to feed on hosts and, crucially, more chances to spread diseases to people and wildlife.
Indirect Threat to Public Health
Cogongrass, native to Southeast Asia, was introduced to the U.S. nearly a century ago and now spans millions of acres, known for outcompeting native plants and increasing wildfire risk. The new findings highlight an indirect but significant public health implication.
“The direct effects of invasive plants are well known, but these finds show that invasions can also indirectly impact human health by prolonging tick survival,” said Luke Flory, professor and director of the UF Invasion Science Institute (ISI).
The study suggests that people recreating in areas heavily invaded by cogongrass are at an increased risk of tick-borne disease.
Implications for Invasive Species Management
This research adds a critical new dimension to the discussion surrounding invasive plant management. Historically, management efforts have focused on ecological and economic impacts.
“This research highlights that they should also be managed to minimize their impact on public health,” Hiatt stated.
The researchers hope the findings encourage policymakers, land managers, and the public to rethink the stakes of invasive species management. They point to previous studies that found a similar link between the aquatic invasive plant water lettuce and malaria outbreaks via mosquitoes, suggesting this phenomenon isn’t isolated.
Increased allocation of resources for invasive plant removal could now be considered a viable strategy for reducing tick-borne disease risk in invaded areas.
READ: Manatee Migration Underway In Florida: FWC Urges Boaters To Slow Down And Be Vigilant
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