Beetle ranchers raise bug to battle invasive plant

Purple loosestrife
Purple loosestrife (Photo courtesy Wisconsin DNR)

STEVENS POINT (AP) – A group of volunteers scattered across central Wisconsin has taken up a new hobby and is raising an army of defenders tasked with fighting off an invasion.

They are beetle ranchers, raising tens of thousands of tiny galerucella pusilla bugs that will be turned loose in the wild where they and their insatiable appetites will mow down waves of the invasive species of plants called purple loosestrife.

Their ranches have no stables or barns. Instead, Karen Dostal and other volunteers have in their yards plants draped in netting and sitting in wading pools filled with vile-looking murky water. That is the preferred environment of purple loosestrife, a plant from Europe that plagues Wisconsin wetlands, where it grows out of control and makes it nearly impossible for native plant life to grow.

The defense until recently primarily has involved treating wetlands with gallons and gallons of herbicide. But now, armies of beetles are being raised to beat back the European invasion, said Kaycie Stushek, the regional aquatic invasive species specialist for the Golden Sands Resource Conservation and Development Council Inc.

“All this project is really doing is introducing a native predator,” Stushek told Stevens Point Journal Media. “They are not going to move on to other plants.”

To raise the army, Dostal, the environmental education coordinator at Boston School Forest, built the wading-pool ranch and planted five net-covered loosestrife stalks upon which her herd of beetles – it started as just five or six bugs on each plant – is feeding.

“Over time they reproduce, and eventually you’ll have thousands of beetles in each one of those nets, and then the beetles are released along the Wisconsin River and other wetland areas where there’s a lot of purple loosestrife, and they will eat it up,” Dostal said.

Purple loosestrife is an unusual invasive. It’s actually quite an attractive flowering plant that also has some medicinal properties. But it can also wipe out native plants in short order.

Stushek said the beetles, which look a bit like tan lightning bugs, weaken the plants and make it difficult for them to flower and go to seed. At this time of year, the beetles are mating and herds are expanding, Stushek said – a happy coincidence during June, which is designated as Wisconsin’s Invasive Species Awareness Month.

“The beetles lay their eggs on the plants,” Stushek said. “When the larvae hatch, they eat the foliage on the plants, then drop down into soil and come out as adults. When they emerge, the plants should be all eaten up.”

The plants are such a problem that the state has one guy, Brock Woods, in charge of controlling them. Woods is the purple loosestrife and wetland invasive plant coordinator for the Department of Natural Resources, and he said the bugs have been working everywhere they’ve been released.

“This is cost-effective and environmentally safe,” Woods said. “It has been one of the most effective biological control projects we’ve ever seen when you consider how little herbicide is used on that plant.”

Stushek said all of the roots and beetles provided to the volunteer ranchers were collected by volunteers and employees of Golden Sands. Amy Thorstenson, executive director of the Golden Sands office downtown and regional aquatic invasive species coordinator for Portage and surrounding counties, said the aim of the project is not to eradicate purple loosestrife, but to weaken the plants and prevent them from spreading. Once the beetles are released, Thorstenson said, they will move about and attack any new invaders they find.

“After they mature and have eaten most of the loosestrife plant, they fly off in search of more,” Thorstenson said. “It’s like free labor from the beetles. I love it.”

The project is supported by the DNR and more than 10 collaborators, including the Wisconsin River Academy, University of Wisconsin-Stevens Point biology students, the Waupaca Natural Resources Foundation, Waupaca County Master Gardeners, and the Waupaca County Land and Water Conservation Department.

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