Colletes is one of the largest genera in the plasterer bee family Colletidae, with roughly 524 valid species on every continent except Australia and Antarctica. All of them are solitary and ground-nesting, and many form gregarious nesting aggregations. Yet the life histories of most species remain poorly described, a gap that falls hardest on rare floral specialists, which are precisely the bees most vulnerable to decline. Colletes andrewsi is a textbook case: prior to this work, researchers knew only that it favored Heuchera pollen and that it ranged across the northern prairie region of North America, from Manitoba south to Colorado and east to Wisconsin. In Minnesota, just five records existed before 2023. After a project targeting rare and specialist bees found the species at numerous new sites by seeking out blooming H. richardsonii, it was ranked as Vulnerable in the state and listed as a Species of Greatest Conservation Need in the Minnesota State Wildlife Action Plan.

The study site at Crow-Hassan offered an unusually favorable setting. Decades of overseeding there had produced an exceptionally large population of Heuchera richardsonii, the only native Heuchera in Minnesota, covering an area roughly 300 meters wide and 500 meters long. At peak bloom on June 10, 2025, the patch held 25,467 flowering stems. The nesting aggregation sat on a dirt road beside this floral bonanza, in predominantly loamy sand classified as excessively well drained. The researchers marked female bees with unique three-color combinations applied to the mesosomal dorsum using non-toxic paint pens, capturing bees from emergence tents, at nest entrances with clear plastic cups, and directly from flowers. Marking appeared harmless; most bees flew off about 30 seconds after release, and many were seen foraging immediately afterward.

Emergence tents placed over the aggregation on May 23, 2025, revealed striking patterns of natal philopatry. Of 49 bees captured in the tents, 34 were females and 15 were males, emerging between May 28 and June 2. Eleven of the 29 marked females were later found nesting in the same aggregation, settling between 1.5 and 13.75 meters from their emergence point, with a mean of 6.22 meters. Excavations confirmed the pattern: brood cells from the previous year were found inside active nests, showing that daughters emerge and nest within the very aggregation where they were born. This nest site fidelity, combined with the bees’ short adult lives, makes the persistence of each aggregation highly dependent on the survival of the site itself.

The nests themselves proved remarkably shallow. Excavation of 16 nests revealed a simple architecture: a small, often inconspicuous tumulus at the surface, a short main tunnel descending vertically or at a slight angle, and a compact cluster of short lateral branches each ending in a vertical brood cell lined with the cellophane-like secretion characteristic of Colletes. From entrance to the deepest cell, nests ranged from just 1.27 to 6.9 centimeters, with a mean of 3.9 centimeters. That is dramatically shallower than the average minimum brood cell depth of around 17 centimeters reported for solitary bees generally, and far shallower than the deepest known solitary bee nest at 270 centimeters. Each nest held 1 to 8 brood cells, averaging 3.93, all provisioned with bright orange-red pollen that the researchers attributed to H. richardsonii based on its color and consistent observations of females collecting only from that plant.

The shallowness carries a cost. Camera traps deployed after the team noticed large patches of dug-up soil revealed a thirteen-lined ground squirrel systematically excavating nests to eat the developing brood and their provisions, in what the authors believe is the first documented account of ground squirrel predation on solitary bee nests. The footage even captured the squirrel catching and eating an adult bee as it flew down to its nest. The predator’s precision was striking: in some cases cell linings remained intact with their contents neatly removed. The researchers note that the shallow nests may facilitate the bees’ habit of constructing multiple nests in quick succession, at least 45 marked females built two nests and eight built three, but the same trait likely leaves brood more exposed to digging mammals. Before the study, there had even been plans to regrade the road at the aggregation site, which would have destroyed every nest.

Foraging data came from 231 trips by 130 uniquely marked females confirmed to be nesting at the aggregation. Distances ranged from 16 to 331 meters, with a mean of 143 meters, on the short end of the spectrum for Colletes, where European species have been recorded foraging 350 to 2,225 meters. The authors suggest this reflects their focus on realized rather than maximum foraging distance. More surprising was the patch fidelity: despite a vast, continuously blooming resource, individual females returned repeatedly to the same spots within the flower patch. One bee foraged 202 meters from the nest on June 4 and was recaptured five days later just 2 meters from the previous sighting. Of 89 fidelity measurements, more than half were within 20 meters of the prior location, and 26 were within 10 meters. Foraging trips averaged 20 minutes and 34 seconds, while females spent an average of only 3.5 minutes inside the nest depositing provisions between trips.

Mating behavior set C. andrewsi apart from many of its relatives. Males, which are typically larger than females, patrolled the H. richardsonii flowers and tackled females as they landed to forage; no males ever patrolled the nest site, and no mating was observed there. Most attempts failed, with both bees tumbling to the ground before separating, but four successful mating events were recorded, each lasting 20 seconds or less. The researchers consider it likely that females mate multiple times throughout their adult lives, though a single-mating scenario cannot be ruled out. Males carried a pungent, musty odor reminiscent of dog food with a hint of citrus, detectable even when walking through flower patches, though unlike in some other Colletes species the scent did not appear to attract mates. Occasional males also tackled other males off flowers, apparently by mistake rather than as territorial aggression.

The aggregation was a stage for other dramas as well. Females fought at nest entrances and inside tunnels when a second female attempted to take over an occupied nest, and marked females were observed starting new nests after their original ones had been usurped. Individuals of the cleptoparasitic bee Epeolus interruptus were seen investigating C. andrewsi nests in 2024, but none appeared in 2025. Ants dragged away only bees that were already dead or dying, and dragonflies, abundant over the prairie, represent a likely but unquantified source of mortality. Many newly emerged bees were found dead or struggling with twisted wings, possibly from disease, though the cause remains under investigation.

The findings translate directly into conservation strategy. Because C. andrewsi depends entirely on H. richardsonii in Minnesota, a plant with a high coefficient of conservatism that favors undisturbed prairie, protecting and restoring high-quality prairie habitat with robust alumroot populations is essential. Because females are philopatric and forage within a few hundred meters, habitat connectivity matters, and the authors suggest that the species’ unusual combination of nest fidelity and flower-based mating warrants population genetics research to understand gene flow. The Crow-Hassan population, roughly six times larger than any other known population of the species, likely owes its size to decades of deliberate overseeding of its host plant, evidence that targeted floral restoration can rescue rare specialist bees. As the authors emphasize, population-level life history studies of solitary and rare bees remain scarce, yet they are exactly what land stewards need to manage and restore habitat for the specialists most at risk of slipping away unnoticed.

Subject of Research: Nesting biology, foraging distance, and mating behavior of the rare specialist bee Colletes andrewsi

Article Title: The nesting biology and foraging distance of the bee Colletes andrewsi ( Hymenoptera , Colletidae ), a rare specialist of Heuchera spp.

Article References: Chase, M. H., Portman, Z. M., Petersen, J. D., Gerjets, N., Kranz, R., LaBry, F., Hudson, D., Lane, I. G., & Cariveau, D. P. (2026). The nesting biology and foraging distance of the bee Colletes andrewsi (Hymenoptera, Colletidae), a rare specialist of Heuchera spp.. Journal of Hymenoptera Research, 99, 703-722. https://doi.org/10.3897/jhr.99.189555

Image Credits: AI Generated

DOI: 10.3897/jhr.99.189555

Keywords: Colletes andrewsi, cellophane bees, Heuchera richardsonii, nesting biology, foraging distance, philopatry, floral specialization, solitary bees, prairie restoration, ground squirrel predation, Minnesota, bee conservation

The research, led by scientists at the Native Plant Initiative at South Dakota State University and published in the journal People and Nature, took an unusual approach for a field dominated by agronomy and ecology. Rather than focusing primarily on seed biology or production technology, the team applied social science methods, along with resilience and systems thinking, to understand the relationships, values, and institutions that hold the native seed system together. Jennifer Zavaleta Cheek, assistant professor in the SDSU Department of Natural Resource Management, explained that native seed systems face ecological, production, and technological challenges, but that understanding them requires looking beyond infrastructure. Culture, knowledge, economics, and interpersonal trust all shape whether the system can withstand shocks and continue supplying seed over decades, not just seasons.

The study was guided from its inception by the Native Seed Strategy developed by the Northern Great Plains Native Seed Partnership, a collaborative plan that explicitly identified the need to understand the social dimensions of seed supply in order to strengthen collaboration and long-term resilience. Elena Friedman, first author of the paper and a master’s graduate from the program in August 2026, worked alongside Lora Perkins, director of the Native Plant Initiative, and Lauren Redmore, a conservation social scientist with the U.S. Forest Service, to gather the evidence. Their central method was qualitative and intensive: 60 detailed interviews with people involved in every facet of the seed network, from collectors and growers to buyers and land managers. What emerged from those conversations was a picture far more intricate than the researchers had anticipated.

The most striking discovery was that the region does not contain a single native seed system at all. The team had entered the project assuming that one interconnected supply chain served the Northern Great Plains, but the interviews revealed multiple distinct seed systems operating simultaneously in the same geography, each with its own participants, relationships, goals, and rules. This finding has immediate practical consequences. Policies or interventions designed for a hypothetical unified system — subsidies aimed at boosting production, for example, or centralized seed banks — might reach only one network while leaving others untouched, or worse, might disrupt relationships that the designers never knew existed.

Among the distinct networks identified, two stood out in sharp relief: the commercial system and the Tribal system. Participants in the commercial network were oriented around collecting, producing, selling, and using seed for ecological restoration projects, functioning much like a specialized agricultural supply chain with market dynamics, quality standards, and customer relationships. The Tribal system, by contrast, shared the goal of ecological restoration but embedded seed within a much broader community context. Tribal participants use native seeds for food and medicine, and they emphasized the significance of seeds in promoting reciprocity and sovereignty — concepts that have no direct equivalent in a commercial supply chain. In this view, seeds are not commodities to be produced in bulk but relatives and inheritances, carrying obligations of care and exchange across generations.

This distinction matters because previous research, lacking a deep understanding of each group’s goals, practices, and connections to native seeds, might have concluded that integrating the commercial and Tribal systems would benefit both by increasing overall production. Such a recommendation, the SDSU team suggests, would rest on a fundamental misunderstanding. Merging systems with different values and objectives could erode the very relationships and cultural practices that sustain the Tribal network, without delivering meaningful gains to anyone. The finding underscores why social-ecological research — work that treats human communities and natural resources as inseparable parts of one system — is essential before well-intentioned interventions are deployed.

Zavaleta Cheek framed the work explicitly in the language of resilience theory. Building resilience in a native seed system, she argued, is not only a matter of having enough seed or the right storage and production infrastructure. It is equally about strengthening the relationships, knowledge systems, values, and institutions that allow both people and native landscapes to thrive together over time. In resilience terms, a system can appear robust while actually being brittle: abundant seed supply means little if the trust between growers and buyers collapses, if Traditional Ecological Knowledge is lost, or if the institutions governing seed use fail to reflect the communities they affect. The interviews captured precisely these intangible assets, which rarely appear in production statistics but determine whether a system adapts or fractures under stress.

The methodological contribution of the study is also significant. Survey-based and interview-based research of this depth is uncommon in native seed science, where most attention has gone to seed sourcing guidelines, genetic matching of seed to ecoregion, and agronomic techniques for propagating native species. By documenting 60 perspectives across the network, the researchers created something akin to a social map of the seed landscape — a baseline against which future changes can be measured. The work also demonstrates the value of qualitative social science for conservation practice: the surprise of discovering multiple parallel systems would not have emerged from production data alone, which tends to aggregate all seed activity into a single supply curve.

The next phase of the research follows two avenues, mirroring the dual nature of the findings. First, the team will continue investigating the relationships between people, native plants, and resilient landscapes, with a new focus on wild foods and the role they play in shaping resilient food systems — a natural extension of the finding that seeds carry meanings well beyond restoration. Second, with support from the Native Plant Initiative, the researchers hope to partner with specialty crop farmers to produce native seed, aiming to expand production capacity and supply for restoration projects across the region. This second avenue represents a practical test of the study’s insights: any effort to bring new growers into the system will need to respect the distinct networks the research identified rather than assuming a single market to be served.

For the researchers, the ultimate message extends well beyond the prairie states. Plants and landscapes are cultural, Zavaleta Cheek emphasized — what we expect a landscape to look like, which plants we value, and what we consider productive or worth restoring are all shaped by culture and by our relationships with those landscapes. Those values, in turn, influence what societies choose to conserve and restore. As prairie restoration scales up across North America and elsewhere, the SDSU study offers a caution and an invitation: the seed may be the foundation of restoration, but the people who gather, grow, and give meaning to that seed are the foundation of the system itself. Sustaining native landscapes for future generations, the work suggests, means sustaining the human networks that make restoration possible.

Subject of Research: Social-ecological resilience of native prairie seed systems in the Northern Great Plains

Article Title: Plants, people and progress for native prairie seeds

Article References: Plants, people and progress for native prairie seeds. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: native seeds, prairie restoration, Northern Great Plains, social-ecological systems, resilience, Tribal seed networks, seed production, South Dakota State University, People and Nature, ecological restoration, seed sovereignty, conservation social science