Cariveau Lab Research

Habitat loss is one of the primary factors leading to the decline in species abundance and richness. Some habitats, such as the tallgrass prairie, have declined dramatically in the past century. For example, tallgrass prairie covered 18 million acres in Minnesota in the early 1900s; now only 1% of this habitat remains in the state. As multiple governmental and non-profit organizations and private landowners work to protect, restore, and enhance tallgrass prairie, we investigate how to most effectively implement and manage prairie restoration, and how restorations affect the native bees of the upper midwest.

We are particularly interested in how prairie restorations affect biodiversity. By sampling bees and plants in prairie restorations and remnants in western Minnesota, we found more oligolectic (“specialist”) bees in remnants in comparison to restorations.¹ Additionally, the lab has found that floral diversity in restorations drives bee diversity, regardless of the agricultural cover in the surrounding landscape.² Another study noted increased numbers of ground-nesting bees in burned areas of prairie remnants.³

We have several ongoing restoration ecology projects, including the Minnesota Agriculture for Pollinators Project (MAPP), which explores how the size of restoration, seed mix, and amount of surrounding natural area impact native bee communities as well as natural enemies of crops. In collaboration with land managers and private landowners, 38 pollinator research plots were planted in 2018 and sampled for insects and floral resources through 2022. Analysis of MAPP data is ongoing.

Land managers looking to reconstruct prairies face the challenge of picking the right seed mix for their restoration – a mix that will make for an effective, diverse restoration while still meeting budgetary requirements. To tackle this challenge, the we began an experiment in 2017 at the U of M’s Rosemount Research and Outreach Center investigating how different prairie seed mix composition (diversity of species, forb vs. grass ratio, seeding density) affects floral and bee diversity, with the goal of creating guidelines for more cost-effective prairie seed mixes. As of 2023, this experiment is ongoing.  

In 2023, the lab began a new project in collaboration with the United States Fish and Wildlife service, comparing how different land management strategies affect prairie remnants and restorations in Minnesota and North Dakota. In the same year, current MS student Maya Vellicolungara began working to collect data comparing the bumble bee populations of prairie remnants with those of land enrolled in the Conservation Reserve Program.

¹Lane, I.G.*, Portman, Z.M. ‡,, Herron‐Sweet, C.R.‡, Pardee, G.L. †,, Cariveau, D.P. (2022) Differences in bee community composition between restored and remnant prairies are more strongly linked to forb community differences than landscape differences. Journal of Applied Ecology 59:129-140.

²Lane, I. G.*, Herron-Sweet, C. R. ‡, Portman, Z. M. ‡, & Cariveau, D. P. (2020). Floral resource diversity drives bee community diversity in prairie restorations along an agricultural landscape gradient. Journal of Applied Ecology. 57(10): 2010-2018. doi: 10.1111/1365- 2664.13694

³Brokaw, J.*, Portman, Z.M.‡, Bruninga-Socolar, B.†, Cariveau, D.P. (2023). Prescribed fire increases the number of ground-nesting bee nests in tallgrass prairie remnants. Insect Conservation and Diversity. https://doi.org/10.1111/icad.12628

To understand how native bee populations respond to restorations, experiments, and changing climate, different approaches to bee monitoring must be utilized. We have published techniques and methodologies for bee monitoring and sampling, including suggestions for making plant-pollinator data collection cheaper for restoration and modeling,⁴ a call to move away from bee bowl trapping and toward more effective methods,⁵ and an approach to increase sampling efficiency for bumble bee occupancy modeling.⁶ We are also involved in a push for a national program for monitoring bees.⁷

PhD student Mary Powley began work on a new monitoring project in 2023, focused on using occupancy models to investigate rusty-patched bumble bee (Bombus affinis) detection probabilities and occupancy across the urban-rural gradient within the Great Lakes watershed of Wisconsin.

⁴Bruninga-Socolar, B.†, Lonsdorf E., Lane, I.G.†, Portman, Z.M.‡ , & Cariveau, D.P. (2023). Making plant-pollinator data collection cheaper for restoration and monitoring. Journal of Applied Ecology. https://doi.org/10.1111/1365-2664.14472

⁵Portman, Z. M. ‡, Bruninga-Socolar, B. †, & Cariveau, D. P. (2020). The state of bee monitoring in the United States: A call to refocus away from bowl traps and towards more effective methods. Annals of the Entomological Society of America. doi:10.1093/aesa/saaa010

⁶Boone, M.L., Evans, E., Arnold, T., Cariveau, D.P., (2023). Increasing sampling efficiency of Bombus communities with rare and endangered species by optimizing detection probabilities: A multi-species occupancy modeling approach using roadsides as a case study. Biological Conservation 283:110122. https://doi.org/10.1016/j.biocon.2023.110122

⁷Woodard, S. H., Federman, S., James, R.R., Danforth, B.N., Griswold, T.L., Inouye, D.,..., Cariveau, D. P., ...W. Wehling. (2020). Toward a U.S. national program from monitoring native bees. Biological Conservation 252: 108821 https://doi.org/10.1016/j.biocon.2020.108821

Under the direction of Dr. Zachary Portman, the Cariveau lab has published extensively on native bee taxonomy. In 2023, a checklist of Minnesota’s native bees was published, with a species count of over 500.⁸ For a full rundown of Dr. Portman’s publications, visit his google scholar page.

Natural history of bees is also a focus of the lab, including findings on nectar concentration behavior⁹ and the relationship between bee body size, sociality, and foraging distance.¹⁰ 

Current MS student Chan Dolan has also spent the last two years surveying bumble bee nests in the St. Croix river valley, working to gain insight on the nesting habits of Midwestern bumble bees, which have otherwise remained understudied.

⁸Bees of MN - Portman, ZM. ‡, Gardner, J., Lane, I.G. †, Gerjets, N., Petersen, J.D., Ascher, J.S., Arduser, M., Evans, E., Boyd, C., Thomson, R. Cariveau. D.P. (2023). A Checklist of the Bees (Hymenoptera: Apoidea) of Minnesota. Zootaxa 5304 (1): 1–95

⁹Portman, Z.M. ‡, Ascher, J. & Cariveau, D.P. Nectar concentrating behavior by bees (Hymenoptera: Anthophila). (2021) Apidologie 52: 1169–1194. doi.org/10.1007/s13592-021-00895-1

¹⁰Kendall, L.K., Mola, J.M., Portman, Z.M. ‡,, Cariveau, D.P., Smith, H.G., Bartomeus, I. (2022) The potential and realized foraging movement of bees are differentially determined by body size and sociality. Ecology 103:e3809. doi.org/10.1002/ecy.3809