On April 22, 2025, Emlyn Resetarits, assistant professor of biology, published new research in the Journal of Parasitology titled “Context-Dependent Effects of Trematode Parasites on Snail Host Feeding, Movement, and Behavior.” This paper explores how parasites can dramatically alter the behavior of their hosts, specifically, a common freshwater snail called Pleurocera proxima. These snails often host trematode parasites, which can take over their bodies in surprising ways, including affecting their ability to move and eat.
In a combination of lab and field experiments, the research team found that infected snails ate fourteen percent more than uninfected ones, likely due to increased energy demands caused by the parasites. However, when given a choice, all snails—whether infected or not—chose to spend more time near other snails than near food.
The researchers also looked at how infected snails moved. They discovered that infected snails moved less when around others, but actually moved more when alone. These behavior changes didn’t seem to affect how far or in what direction the snails traveled in the wild.
This study shows that parasites can have complex effects on animal behavior, and that these effects may depend on the social environment. The findings could have broader implications for understanding how parasites influence the ecosystems we all share.