New bee species found in Montana

Delphia, an assistant research professor in the Department of Plant Sciences and Plant Pathology in MSU’s College of Agriculture, has found that her own garden is often an excellent place to find pollinators. In 2021, she managed to catch a small, skinny black bee that looked unfamiliar.

“I brought it inside and looked at it under the microscope. It had some characteristics that reminded me of one genus, but other characteristics that reminded me of another genus,” Delphia said. “So, what the heck is this?”

Consultation of existing taxonomic literature about bee species in the U.S. showed that the bee is from the genus Chelostoma, a type of bee that nests in cavities such as plant stems or holes in trees. But only one species of Chelostoma bee was known to live in Montana, and this one clearly didn’t match.

The newcomer to Delphia’s garden was ultimately identified as Chelostoma campanularum, a non-native species introduced to eastern North America from Europe and only known as far west as Michigan. The first sighting of Chelostoma campanularum and a related species, Chelostoma rapunculi, another European species only known as far west as Illinois, were documented in a paper by Delphia that appeared this summer in The Pan-Pacific Entomologist.

Introduced bees frequently experience habitat expansion, and documenting when they appear in new regions is a key part of Delphia’s work.

“We know so little about what is present in Montana,” Delphia, who has been part of the Wild Bees of Montana project since 2014, said. “People ask all the time, how are our bee species doing here? And we have no idea. We need to know what we have here first. And once we know what we have, then we can monitor what's here and how they’re doing.”

The two Chelostoma species are not the first introduced species that Delphia has recorded in the state. In 2019, she published a paper in the Journal of the Kansas Entomological Society documenting the first recorded sighting of Xylocopa virginica in Montana, a species of carpenter bee that is often confused with bumble bees, which she also encountered in her own backyard garden.

Each time a new species is documented, it is verified by bee experts before being incorporated into MSU’s Montana Entomology Collection (MTEC), a museum that includes more than 3 million invertebrate specimens.

While the goal of cataloging every species in the state is a daunting one, Delphia said the opportunities for discovery are one of the most rewarding aspects of her work. The documentation process also creates and strengthens relationships with taxonomists, entomologists and other experts from around the country.

“The idea that we can still make new discoveries is astounding,” Delphia said. “When we think about what bees live in Montana, it sounds like such a basic question. But we don't know that, and then the surprises we're finding are amazing. We just keep finding exciting things. Maybe a lot of them have always been here and we're just now discovering them, or maybe they’re new.”

Delphia noted that the recent papers add context to existing knowledge about how bee distributions shift over time. They could have found their way west on their own or could have been introduced by human travel.

Since Chelostoma bees often nest in the hollow stems of plants, they could be hiding in many small spaces such as outdoor furniture, birdhouses or fencing that gets transported from one place to another. Though not native to the U.S., no negative impacts of these species have been documented on the ecosystem, Delphia said.

While inclusion of a new species record into the Wild Bees of Montana project requires extensive verification by experts as well as physical samples of the species, Delphia says anyone can help contribute to wild bee research by simply keeping their eyes open and taking pictures of pollinators they encounter.

Online resources such as iNaturalist and BugGuide allow users to upload pictures of specimens, where a community can help to identify them. Those kinds of resources have helped Delphia and her fellow researchers determine how far a new bee may have traveled from an established population elsewhere, or how their existing range may be expanding.

“It's a great way for us to see what people are seeing and reach out to those people or go to that location and collect specimens,” she said. “The more I learn, the more I realize how much more there is to know. We have to question everything, but I think that’s good."