Trophic interactions and the efficacy of the milfoil weevil (Euhrychiopsis lecontei) as a biocontrol of Eurasian water-milfoil (Myriophyllum spicatum)

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Aquatic Invasive Species (AIS): Eurasian Watermilfoil (Myriophyllum spicatum)
Project Location: Northern Wisconsin
Project Start Date: 04/2014
Expected Timeframe/Duration: 12/2015
Sponsoring Organization: WI Department of Natural Resources
Web Links:
Primary Contact: Kristopher Maxson
Missouri State University

Secondary Contact: John Havel
Missouri State University
Project Summary:

The native milfoil weevil (Euhrychiopsis lecontei) is being investigated as a possible biocontrol method for management of Eurasian water-milfoil (EWM) in northern lakes. One concern with using this method of biocontrol is the fate of weevils following introduction. The black-and-white-striped adults (ca. 3mm) are conspicuous to the naked eye and presumably also to sight-feeding predators such as sunfish. Milfoil weevils have been previously reported from the stomachs of bluegill and pumpkinseed sunfish in Minnesota, suggesting that high densities of sunfish may limit weevil densities. The overall goal of the current project is to determine the impact of sunfish on weevil populations and whether variation in reported fish community structure explains differences between weevil populations that thrive and those that decline during summer. In 2014, I collected fish diets and environmental samples from four study lakes in northern Wisconsin and am currently analyzing the samples.