Lyme Disease-Toting Ticks Abundant on Common Invasive Plant, New Study Finds

The greater amount of Japanese barberry growing on a property, the greater amount of Lyme disease-carrying ticks you are likely to have.

That is the conclusion of a recent study by Amber L. Pitt, Trinity College associate professor of environmental science and biology, Trinity alumna Bailey E. D’Antonio ’18, and Krista Ehlert, South Dakota State University assistant professor, and published in the March issue of BIOS, the journal of the Beta Beta Beta Biological Honor Society.

Researchers looked at populations of blacklegged ticks and white-footed mice, known to transmit and harbor Lyme disease, respectively, across three different habitats in Connecticut: a site fully invaded by Japanese barberry; a site partially invaded; and a non-invaded site.

They found the abundance of Japanese barberry correlated directly with the abundance of the two species. Habitat management that prevents full invasion of Japanese barberry may also limit the abundance of Lyme disease-carrying species and help reduce the disease spread.

“Removing Japanese barberry from properties may lessen your chances of contracting Lyme disease,” said D’Antonio ’18, who pursued the research for her undergraduate thesis in biology. “And understanding the relationships between invasive species and agents of disease can inform management measures and policy changes.”

In all, researchers collected 55 blacklegged ticks: 38 in the full barberry habitat; 11 in the partial barberry habitat; and 4 in the habitat without barberry. With white-footed mice, they collected 43: 29 in the full barberry habitat, 16 in the partial barberry habitat, and 1 in the area without barberry.

Previous studies have pointed to favorable microclimates such as humidity as a factor in the reason ticks are attracted to the Japanese barberry.

However, additional characteristics may influence the tick abundance, according to the authors. The thick and dense branches of Japanese barberry provide more questing space—area to attach to a host—than native plant species. The white-footed mice that serve as reservoirs for Lyme disease may use Japanese barberry to avoid predators who are held off by the dense, thorny shrub, said the authors.

Native to Japan, the barberry escaped managed landscapes and invaded deciduous forests in this U.S., negatively altering native plant abundance and ecosystems.

People can help prevent and control the prevalence of ticks, mice, and Lyme disease by avoiding planting Japanese barberry and removing it from their landscaping where it already occurs, Pitt noted.

Researchers collected the data on publicly accessible conservation land owned by the Simsbury Land Trust in Simsbury, Connecticut, where mixed hardwood forests dominate. At the time of study, Ehlert was the Thomas McKenna Meredith ’48 Postdoctoral Fellow in Environmental Science at Trinity. The findings have been featured in the journal’s “Top and Trending Research” in the ecology division.

Pitt co-authored two additional recently published research papers: