PELLSTON, Mich. — What’s living inside a pine cone?

A simple field observation by undergraduate students in the Field Studies of Insects class at the University of Michigan Biological Station (UMBS) last summer turned into an unexpected, promising lead that faculty researchers will investigate this summer.

The Field Studies of Insects class examined red pine cones and acorns at UMBS during the 2025 summer term.

Colonies of “acorn ants” — tiny cavity-nesting ants commonly found in acorns hollowed out by seed-eating beetles — were found nesting inside red pine cones scattered across the forest floor at the campus in Pellston along Douglas Lake.

That observation and further examination by Field Studies of Insects students taught by Dr. Nate Haan from the University of Kentucky grew into a cross-course collaboration with students and faculty in another U-M Biological Station class: Field Mycology, taught by Dr. Tim James from the University of Michigan.

That’s because the classes also found evidence of ant-associated fungi inside the cones, which suggests there may be an unexplored microbial dimension to the interaction network among ants, pine cones, beetles and fungi.

U-M junior Skyler Umney, left, who majors in ecology and evolutionary biology, and Dr. Nate Haan, the instructor of Field Studies of Insects class at UMBS in July 2025, talked about the relationship between pine-cone boring beetles, ants, and larvae.

Opening the door to a new line of research into tiny ecosystems hidden inside red pine cones, Haan and James are returning to UMBS this summer to explore the relationships.

“The first fun natural history moment was, ‘Oh cool, look at all these acorn ants nesting in pine cones — I didn’t know that was a thing,’” Haan said.

Haan and his students first documented the ants using the fallen pine cones as nest sites.

In eastern North American forests, cavity-nesting ants are often associated with acorns that have been hollowed out by weevils or other seed predators. But at UMBS, students found ants using red pine cones that had been tunneled through by a scolytine beetle, Conophthorus resinosae.

Field Studies of Insects students began collecting data to find out how common the phenomenon was and whether ants appeared to prefer pine cones, acorns or neither. That work has since been written into a manuscript submitted to the natural history section of a peer-reviewed journal and is currently in revision.

U-M junior Skyler Umney, who majors in ecology and evolutionary biology, examined pine cones gathered at UMBS in July 2025.

But as students examined more pine cones, they noticed something else: fungus.

At first, Haan said, they wondered whether it might be an ambrosia fungus — a type of fungus that some bark and ambrosia beetles carry into wood, where it grows and becomes food for their larvae. The beetle associated with the red pine cones at UMBS is not known to cultivate ambrosia fungi, but the possibility raised an intriguing question.

That’s where the collaboration with Field Mycology came in.

One undergraduate student, Skyler “Skye” Umney, a junior at U-M majoring in ecology and evolutionary biology, was enrolled in both Field Studies of Insects and Field Mycology during the 2025 summer term.

Curious about the fungus appearing in the pine cones, Skyler helped bridge the two courses and pushed the question forward: Could they sequence the fungal sample and identify what was living there?

“When we were opening the pinecones, I noticed that there was a lot of fungi in the ones that had the ant cavities,” Umney said, “so I suggested that we have it sequenced in the lab. We were already sequencing stuff in the mycology class.”

On July 15, 2025, Dr. Tim James, right, instructor of the UMBS Field Mycology course, and Rae Zosel, who was a senior at U-M studying Programs in the Environment (PitE) during the 2025 summer term, looked at different aquatic and shoreline plants on Douglas Lake, studying them for fungal pathogens.

Thanks to new Oxford Nanopore sequencing technology purchased by UMBS, the answer was yes, and quickly. The portable sequencing platform can be run in Stockard Lakeside Laboratory with a laptop and generate data overnight, allowing students to investigate microbial communities in near real time.

“The way that we could do this in real time was facilitated by UMBS investing in Oxford Nanopore sequencing technology,” James said. “This platform allowed us to sequence a complex sample rapidly. I hope future classes will continue to include this technology into their curriculum as it is a great way to explore the microbial world.”

One of the pine cone samples produced a result that caught everyone’s attention: a hit for Capronia epimyces, a species of black yeast which is known to associate with ants.

That finding is preliminary, and Haan and James both emphasize that much more work is needed before drawing conclusions. But the result was fascinating because Capronia fungi are known to be associated with certain ants in tropical systems, including ants that line nest cavities with fungal hyphae. In those systems, the fungi may provide structural support or antibacterial functions within the ants’ nests.

On July 10, 2025, Anna Grotelueschen, a junior at U-M studying Programs in the Environment (PitE) with a minor in ecology and evolutionary biology, opened pine cones around State Street on the UMBS campus, looked for ants, beetles and larvae as part of her Field Studies of Insects course.

Whether anything similar is happening in northern Michigan remains an open question.

“What sparked our interest is that one of the pine cones came back as containing Capronia epimyces,” James said. “We need to go back to UMBS to test how frequent this association is and to test whether these ants may be specifically introducing the fungi to the pine cones for their benefit.”

Haan said the possibility is exciting, but still uncertain.

“To my knowledge, we don’t know of any such relationship occurring in temperate environments,” Haan said.

This summer, Haan and James will return to UMBS to continue what the students started.

Their next step is to examine the microbial communities associated with ant nests in both acorns and pine cones, testing how often fungi such as Capronia appear and whether the fungi may be helping ants use pine cones as homes or whether they are simply present in the same cavities.

Students in the 2025 Field Studies of Insects course did field work along Douglas Lake at UMBS.

James said this year’s work will help determine whether the fungus is facilitating the ants’ use of pine cones or “just in there trying to compete.”

The project underscores the value of field-based teaching and research at UMBS, where students, faculty and new technology can converge around an unexpected observation.

“A pine cone on the forest floor may seem ordinary,” said Dr. Aimée Classen, director of UMBS, “but inside, students found a miniature ecosystem of ants occupying beetle-made tunnels, fungi growing in the cavities and a set of questions that now stretches across entomology, mycology and plant biology.”

Adyaan Menon, a senior at U-M who majored in ecology and evolutionary biology, collected data as part of his work in the Field Studies of Insects class In July 2025.

For Haan, James and their students, that is exactly the kind of discovery the Biological Station makes possible: curiosity sparked in the field, tested in the lab and carried forward into new research.

“It’s hopeful. It gives us more direction,” Umney said.

The overall experience at UMBS last summer was so pivotal for Umney that he has already returned this year to take 2026 spring and summer courses.

“When I came here last year, I was not very confident in my abilities to do research. It was very shocking to come here and realize I do have the potential,” Umney said. “I love the BioStation.”

 

The University of Michigan Biological Station serves as a gathering place to learn from the natural world, advance research and education, and inspire action. We leverage over a century of research and transformative experiences to drive discoveries and solutions to benefit Michigan and beyond.

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Founded in 1909, UMBS supports long-term research and education through immersive, field-based courses and features state-of-the-art equipment and facilities for data collection and analysis to help any field researcher be productive. It is where students and scientists from across the globe live and work as a community to learn from the place.

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On July 10, 2025, Anna Grotelueschen, a junior at U-M studying Programs in the Environment (PitE) with a minor in ecology and evolutionary biology, spent the afternoon on State Street with her Field Studies of Insects course opening pinecones in search of ants, beetles and larvae. She is sitting at the Chatterbox along Douglas Lake recording results.