Another option? Studying weevils' ability to control invasive species in Northwoods lakes Submitted: 08/19/2014
BOULDER JUNCTION - The problem of invasive Eurasian Watermilfoil in Northwoods lakes never seems to stop. Lake groups can cut it, but it often grows back. Chemical treatments often work, but they put artificial ingredients into lakes. What if there was another option? We found one group on the hunt for one.

"We're on Boot Lake," Nick Winter says as we motor onto the water body near Eagle River. The Lakeland Union High School graduate and current Minnesota-Duluth undergrad loves spending days on the lake. "It's kind of fun to be around people that are as passionate about environmental problems as you are," he says. Nick and two other college students are working on a study through the UW-Madison Trout Lake Station in Boulder Junction. Everything they do revolves around creatures only a few millimeters long. "A weevil is a small insect and it's aquatic, so it lives underwater," Susan Knight explains. She leads the project, which studies what impact these weevils have on invasive Eurasian Watermilfoil. "They burrow down into the stem and eat their way down the stem," Susan says. "As they're eating the stem, that is killing off at least the top of the plant." On the boat, Nick helps put a handful of plants into a Ziploc bag. "These are going to be the plants that we're going to use to search for weevils," he says. Last year, thousands of weevils were set free in three test lakes. Susan, Nick, and the team want to find out if they're effective in killing the invasive milfoil. "It would be really nice to know that there is a biological control," Susan says. "Some means of control that is not chemical." Besides just the sample stems, "we take a biomass sample," Nick explains, "so we go take a rake pull and get all of the biomass that we can off of that." Then, all of the samples are shuttled back to the lab. "We have a pan for all of the natives and a pan for just the Eurasian. They'll go into a big drying oven for a few days," Susan explains. "We think that weevils would be a success if we saw more natives and less Eurasian." While part of the team weighs the dried biomass, others spend hours peering into microscopes. "It's kind of a necessary evil," Nick says about the lab work, laughing. "This is where we get all of the important information for our study." "They will examine those plants to see whether or not there are weevils at any life stage: eggs, larva, pupae, and adults," Susan says. The team picks out and preserves samples of the insects in all four stages. They're the focus of all of the effort leading up to what Northwoods researchers hope is a firm answer. "If we could get a clear-cut result and say, weevils did or did not have any effect on the biomass, that would be ideal," Susan says. They've still got plenty of data collection and number-crunching left to do before they find that answer. But until then, on the water is not a bad place to spend a college summer. "I feel like what we're doing is kind of like trailblazing," Nick says proudly. "It's a big project."

Story By: Ben Meyer

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