Research Highlights

Parasitic Nematodes Control Slugs

By Laura Temple

Slugs consistently cause damage to young soybeans in Atlantic states, and their populations increase with the level of groundcover in fields.

“Slugs are especially problematic at the establishment of the crop in the spring or in fall,” reported Ivan Hiltpold, Ph.D., former assistant professor at the University of Delaware. “Mollusk outbreaks have become a serious concern for growers in non-tillage systems.”

In the mid-Atlantic region, about 70 percent of agriculture land is no-till to prevent soil erosion and runoff. However, this environment supports the build-up of slug populations, and control options all have drawbacks. In fact, 92 percent of no-till soybean growers experience significant slug damage. And 82 percent of growers surveyed by university researchers think slugs are the most challenging pest they face. 

Tillage can help manage the pests, but slugs tend to be more resistant to mechanical disturbance than other mollusks like snails. Chemical control options offer notable downsides, including cost and a propensity to leach in wet conditions, impacting groundwater and ecosystems. 

“One largely overlooked approach is the use of the ecosystem services provided by slug natural enemies,” Hiltpold said.

An alternative tool, slug parasitic nematodes, could be used alongside of or in place of chemical controls. This species of nematode does not impact soybeans. But it can infect slugs, and, as a parasite, kill them in about one week. A research project funded by the Atlantic Soybean Council surveyed slug populations in Delaware, Maryland and Pennsylvania to determine the prevalence of slug parasitic nematodes.

The presence of this type of nematode has not been well-documented in U.S. soils. “Despite their great potential in slug control, very little is known about native slug-parasitic nematodes in the mid-Atlantic region,” said Hiltpold.

The project found slug parasitic nematodes naturally occurring in about 20 percent of the slug population surveyed in the Mid-Atlantic region. Learn more from this video created by the University of Delaware, which took the lead in the multi-institution research.

This species can be commercialized, as it has been in Europe, as a slug control option. This project contributed to the current knowledge of slug parasitic nematodes in a region where slugs are a serious pest, and soybean farmers need additional control tools.

Published: Dec 21, 2020