eurasian watermilfoil

MAISRC research on Eurasian watermilfoil focuses on finding biological controls; integrating control with enhancement of native plants; and studying the distribution, ecology, and management of hybrid watermilfoil that arises from Eurasian watermilfoil crossing with the native species, northern watermilfoil. Click here to learn more about Eurasian watermilfoil and its impacts.

Key findings and accomplishments

  • Developed and evaluated techniques to selectively control Eurasian and hybrid watermilfoil using native milfoil weevils
  • Conducted enclosure and mesocosm experiments, as well as lake surveys, to assess the effect of sunfish predation on milfoil weevil densities and watermilfoil abundance to inform biocontrol strategies
  • Determined that weevil populations are too low to control watermilfoil in many Minnesota lakes and that other factors, in addition to sunfish predation, are limiting populations
  • Determined performance and fecundity of milfoil weevils on native, hybrid and Eurasian watermilfoil and in relation to host plant chemistry and quality
  • Identified hotspots for Eurasian watermilfoil based on environmental variables and potential pathways of spread
eurasian watermilfoil

Ongoing research

  • Quantifying the genetic diversity of Eurasian, hybrid, and northern watermilfoil across the state to establish if the different genetic varieties present increased invasiveness or tolerance to current control techniques
  • Investigating the ecology and invasiveness of hybrid watermilfoil, in comparison to native plant communities, to evaluate impacts and develop, prioritize, and refine management strategies
  • Identifying pathogenic microbes associated with Eurasian watermilfoil and evaluating their specificity and effectiveness as biocontrol agents
  • Studying the distribution, ecology, and management of hybrid watermilfoil
  • Surveying lakes for abundance of milfoil weevils and other herbivores in relation to sunfish densities
  • Examining sunfish diets to determine extent of predation by sunfish size
  • Conducting mesocosm experiments with different densities of sunfish to experimentally determine the effects of sunfish on herbivores and milfoil control