A lifetime that lasts a season: Rusty patch bees in the Driftless
Bumble bee species are essential for the pollination of wild forbs and food crops, including tomatoes, squash and many others. (Steve Van Kooten/Courier Press)
A close up of a captured rusty patch bee taken by Upper Mississippi Fish and Wildlife Refuge in 2023 (Submitted photo)
By Steve Van Kooten
The Driftless Area, which encompasses portions of southeast Minnesota, southwest Wisconsin, northeast Iowa and northwest Illinois, is a unique region. Millions of years ago, a shallow ocean covered the area, and an array of prehistoric fish and sea life populated it. During the Ice Age, it escaped glacial encroachment, a circumstance that gave the area its moniker.
The area is marked by many distinctive features, including plant and animal life that rarely coexist in other areas. Plant species common in disparate climates rub shoulders here, and many endangered or threatened species, large and small, make their homes in the area’s verdant wilderness.
Among those species is the rusty patch bumble bee, an insect species that was placed on the endangered species list in 2017 in the United States and Canada. The species has suffered population loss for many years, but members of the Upper Mississippi Fish and Wildlife Refuge Service discovered new populations in the Driftless Area.
“We knew it has been in the refuge, but they’re documenting where it could be found, and this could be a range expansion of where we know that it is,” said Kendra Pednault, manager of the Upper Mississippi River National Wildlife and Fish Refuge — McGregor District, which monitors and maintains refuge areas between Genoa, Wisconsin and Cassville on pools 9–11 on the river.
“It’s range used to be the entire eastern United States down to the Carolinas, up to Maine and into Canada and east to the Dakotas,” said Pednault. “It’s range has decreased dramatically. It shows how much our pollinators have declined lately.”
“We’re going to add one more dot to the map, which is exciting,” said Alexandra Ogdahl, a biology technician who identified the species during a series of seven surveys of the Upper Mississippi and Driftless Area refuges. It’s another resource to gather data to determine the species priority as a threatened or endangered species, which will assist in the implementation of the rusty patch’s recovery plan.
The rusty patch used to be prolific in Wisconsin. It was a half-inch workhorse ubiquitous around the Mississippi River with an affinity for sunflowers and honeysuckles, among many other flowering plants; however, pesticides and invasive species have reduced its numbers. Even as their numbers decreased and its range got smaller, the bee has remained in Wisconsin, which Pednault called one of the species nesting strongholds.
Along with pesticides and anthropogenically introduced invasive species, the advent of agricultural development further burdened the rusty patch, taking away the variety of plants and habitats that best sustain its year-long life cycle.
“They’re getting these food deserts. That happens a lot with agriculture; it’s all corn, which only blooms once a year, and the bees can only get pollen one time of the year, where they need to get pollen to see them through the early spring and all through the summer,” Ogdahl said.
Through a lifetime that lasts a season, fertilized queens emerge from hibernation and give birth to worker bees to forage during the summer months. In the late summer, male bees will fertilize queens to help perpetuate the species. To do that, they need spring forbs, summer crops and prairies, and they need late-blooming plants like sunflowers and goldenrods to feed on.
“They need to fatten up on pollen and nectar,” said Ogdahl. “That’s why they need those fall blooming resources.”
The elimination of preferential habitats has made life harder for bumble bees, which do best in areas that offer woodlands for overwintering and prairies for food sources. Bumble bees do not typically wander far to forage, often staying within 1,000 meters of their nest to find food.
Despite the rusty patch’s struggles, it has the ability to adapt. Urbanization and human encroachment do not seem to stifle it in the same way as croplands.
“People will find them in their gardens; they’ll find them in the foundations or under the steps of their house,” said Pednault.
According to Ogdahl, the health of the rusty patch bee is important for the Driftless Area because of the role the bee plays in the environment. The rusty patch is one of many pollinators; however, many honey bees, for instance, won’t go to certain plant life, such as tomatoes, squash and many vegetables used for food, leaving bumble bees as a primary vector for pollination.
“That is an essential environmental service we need to get crops; you’re going to need bumble bees for that.”
The rusty patch plays an integral role in maintaining habitat biodiversity. The more native species of plants or animals in an environment, the more resilient the entire ecosystem is to population crashes that could leave a habitat without an important cog in the system or too few species to shoulder the responsibility of an essential process, such as pollinating plants.
“A big part of this is protecting pollinator populations in general,” said Ogdahl. “What is affecting the rusty patch bee is also affecting most pollinator populations. You want as many options as possible to continue those processes.”
The Wildlife Refuge will continue to monitor the rusty patch, along with many other species, on the 92,000 acres that fall under the McGregor district’s responsibility. Interventions include prescribed burns, the introduction of new seed mixes and mowing to create the best environment for the bee and other species to continue on. Along with that, the refugee has to consider political and regulatory variables.
“The ultimate goal is recovery,” said Pednault. “You don’t want it on the Endangered Species Act. You want to be able to de-list it. Our primary goal is to protect species for future generations.”
