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Biological Control of Non-Native Species

Eurasian MilfoilCan you be green by eating green? That's the question that the DNR Parks and Recreation Division wants to answer in a new pilot project to combat Eurasian milfoil, a non-native invasive species negatively impacting Michigan's inland lakes.

Sleepy Hollow State Park is the test location where officials from the DNR's Parks and Recreation Division and Fisheries Division will address an ongoing problem impacting boating, fishing and overall water enjoyment.

Lake Ovid at Sleepy Hollow State Park is a popular fishing, boating and swimming location for recreation enthusiasts. These uses are being impacted by a little green water-based plant that creates a heavy mat of weeds. This mat encompasses 75 percent of the of the lake surface, according to a 2005 Department of Enviromental Quality study.

Besides recreational impacts, which have been affecting the park's attendance and revenue, Eurasian milfoil can dominate a lake's ecology and reduce the native plants that fish feed on. Since it was observed in a pond in Washington, D.C., in 1942, Eurasian milfoil has been spread throughout the country by aquarium dealers and fishermen. The plant disperses primarily by vegetative propagation through stem fragmentation. Boat propellers and trailers play a critical role in long-distance spread of the plant.

At Sleepy Hollow State Park, staff have researched and found funding to try a natural biological, non-chemical way to combat this problem in the form a small beetle, the milfoil weevil (Euhrychiopsis lecontei). The milfoil weevil is an herbivorous aquatic beetle, belonging to the family Curculionidae. It is a milfoil specialist, meaning that it feeds and develops only on plants in this genus. The weevil completes all life stages fully submersed and the larvae are stem miners. These characteristics make it very unique as specialist herbivores are very rare among aquatic insects. These characteristics are precisely why the milfoil weevil has shown the most promise as a potential biocontrol agent for Eurasian watermilfoil and why it has been the subject of much research.

This multi-year project and study at Sleepy Hollow will include lake mapping, weevil stocking and follow up surveys and reporting. If proven successful, this could be a model for other lakes that are being impacted by this invasive species.

Eurasian Watermilfoil