Several thousand tiny weevils are set to be released on June 18 in four sites in Calhoun County to target the invasive mile-a-minute weed in Michigan.
In the coming weeks, the Barry, Calhoun, Kalamazoo Cooperative Invasive Species Management Area will test Michigan’s first release of the mile-a-minute weevil.
The weevils, a small herbivorous beetle, are being utilized as a biological control agent in an attempt to reduce populations of the mile-a-minute weed.
Katie Grzesiak is the terrestrial invasive species coordinator for the Michigan Department of Natural Resources. She said the highly invasive vine is currently limited to Calhoun County.
She said despite the weed only being located in one county, prevention measures are critical to avoid further ecological damage.
“Mile-a-minute weed is not native. It meets the definition of an invasive species, right, which is two parts, it is not native and it causes harm,” said Grzesiak. “It lives up to its name, it grows very, very quickly and it is able to reproduce multiple times in a year, as well as over winter, so it can be a really big problem.”
Grzesiak said the DNR wants to test how well the weevils can control the invasive vine.
“This is much more of a research opportunity. We are trying to find out if this biological control, which is approved by the USDA, could be a good tool in our tool box,” said Grzesiak.
The DNR said these weevils have been safely and effectively used in the United States as a biological control since 2004. This release will be Michigan’s first test of weevils in that way.
Grzesiak said that because the U.S does extensive testing on biological controls, researchers have determined that the weevils can eat other plants, but they are not able to reproduce on them. She said it’s expected the population of weevils will simultaneously diminish as they feed on the mile-a-minute weed.
This project will be isolated to four infested sites in Calhoun County, with each site receiving 1,000 adult weevils on June 18. These four locations will be monitored by the Barry, Calhoun, and Kalamazoo Cooperative Invasive Species Management Area staff and researchers from Grand Valley State University every two weeks for approximately one year to monitor plant damage, population size and spread.
Grzesiak said the number of weevils her team is set to receive was not up to them.
“We actually didn’t do any determination of that, that came from the supplier. They said we ship these in amounts of one thousand,” said Grzesiak.
The DNR says the invasive mile-a-minute weed is known to take over forest and field edges that are essential for wildlife. The weed can invade agricultural sites such as hayfields, orchards, vineyards and Christmas tree farms as well.
The mile-a-minute weed can be recognized by its bright green, triangular leaves, and barbed stem. By mid-summer, the plant produces clusters of round, pea-sized fruit, ranging in color from light green to purple. When fully ripe, the fruit clusters are a metallic blue.
“Folks anywhere in Michigan can get involved with invasive species. Any invasive species is worth taking note of and managing if it is on your property, or reporting on the Midwest Invasive Species Network,” said Grzesiak.
