A century of change for bees and their floral associations

Wednesday, November 16, 2022

1:30 PM – 1:42 PM PT

Location: Vancouver Convention Centre, Meeting Room 221/222

Presenting Author(s)

EE

Elaine C. Evans (she/they)

Assoc Extension Professor
University of Minnesota
Saint Paul, Minnesota

Co-Author(s)

JA

John S. Ascher

National University of Singapore
Singapore, Singapore
DC

Daniel Cariveau

University of Minnesota
Saint Paul, Minnesota
MS

Marla Spivak

University of Minnesota
Saint Paul, Minnesota

To examine changes in bee communities and bee–flower relations in the Prairie Pothole Region of the Northern Great Plains, we compared bee specimens and their floral associations collected in eastern North Dakota from 2010–2012 to bee specimens and their floral associations collected from the same region from 1910–1920 by pioneering naturalist O.A. Stevens. We also examined citizen science photographic records from 2012–2021. Using rarefaction, we found similar estimated bee species richness between the 1910s (135.98 ± 9.82) and the 2010s (125.42 ± 8.14). Bumble bees were less frequently present in collecting events in the 2010s, with 1 bumble bee species, Bombus terricola, declining from 7% presence in collecting events in the 1910s to 0.4% in the 2010s. Hylaeus annulatus, Andrena miranda, and Hesperapis carinata were each in the top 25% of species most frequently present in collecting events in the 1910s but were absent in the 2010s. Citizen science images documented range expansions for Bombus impatiens and the non-native Anthidium manicatum. Based on the floral association data, we recommend that pollinator plantings include (1) plants that were formerly common in bee-association records but that had decreased presence or were absent from modern collections and (2) plants visited by possibly declining bee species, as indicated by historic plant- associations for bee species that were absent or less frequently present in modern collecting events. The persistence of many bee species, including those of conservation concern, in agriculturally dominated landscapes points to the importance of restoring key floral resources to wide-ranging habitats.