Andrena cragini

Justification:
Andrena cragini is a solitary bee known from just 25 observations. It occurs in the central United States, from Kansas north to North Dakota and Minnesota. Using all observations, the extent of occurrence is 737,590 km2. The species has not been observed anywhere in its range since 2012. It is not clear if the species is extant throughout its entire range. The species is a dietary specialist that visits plants from the genus Amorpha (Fabaceae) for pollen, and occurs in the midwestern United States grasslands, which have experienced significant degradation over the last two hundred years. Across the range of the species, impacts from agricultural conversion, fragmentation, and exposure to pesticides have been observed. These threats may be acting on the species at local levels. More information is needed to determine if this species is extant throughout its entire range, to assess its population status, and the degree to which threats are acting on the species. RANK SENTENCE.

Food habits comment: Andrena cragini is possibly a dietary specialist, collecting pollen from the plant genus Amorpha (Fabaceae) to provision nest cells (LaBerge 1977). Habitat comment: This species has been recorded in grasslands between 218 and 1,357 m Reproduction comment: This species likely nests underground like all other Andrena (Danforth et al. 2019), but nests from this species have not been described. Nest cells from other members of this genus are located at the ends of the lateral burrows, which are typically lined with a waxy Dufour’s gland secretion (Cane 1981) that serves to both isolate the provision from pathogens in the surrounding soil and to regulate water uptake from the soil atmosphere (Cane and Love 2021). Females provision each cell with a ball of pollen moistened with nectar on which they lay a single egg (Michener 2007). Phenology comment: Records of this species come from May and June (Chesshire et al. 2023). Adults are assumed to emerge annually (Danforth et al. 2019).

Threat comments: Threats to this species have not been directly studied. This species occurs in the Great Plains region of the United States, a landscape that has seen major habitat loss and modification in the last 200 years (Samson and Knopf 1994). Much of this modification has resulted from agricultural conversion, which has both altered the plant community composition, and increased the potential for exposure to pesticides at levels lethal for bees. The remaining prairie ecosystem within the range of the species is made up by habitat fragments of varying size. Habitat loss due to fragmentation and also increased habitat disturbance via roads have been shown to negatively influence bee abundance in prairie ecosystems (Olynyk, Westwood, and Koper 2021). Fragmentation can also decrease plant diversity, contributing to reduced bee abundance (Winfree et al. 2009; Glaum et al. 2017; Theodorou et al. 2020). Lack of connectivity between habitat fragments can contribute to reduced genetic diversity, as bees may not be able to travel between habitat fragments to mate (Tscharntke et al. 2005). Certain aspects of this species' biology may make it more vulnerable to some threats. Andrena cragini is a ground nesting species, and nests may be harmed by certain agricultural practices such as tilling, which can kill bees nesting close to the surface (Williams et al. 2010). This species is a dietary specialist, which has been linked to higher risk of extinction due to reduced host plant availability, especially under climate change scenarios (Roberts et al. 2011) and reduced effective population sizes (Packer et al. 2005). Additionally, Andrena have been reported to have low reproductive output because of the short adult life span, and a low rate of brood cell provisioning (reviewed in Danforth et al. 2019). Other threats to bees generally include habitat loss or modification, climate change, pesticide use, exposure to pathogens from managed bee species, and competition with honey bees (Brown and Paxton 2009; Potts et al. 2010; Wojcik et al. 2018; Grab et al. 2019; Raven and Wagner 2021). Threats Threats: Timing: Scope: Severity: Impact Score: 2. Agriculture & aquaculture -> 2.1. Annual & perennial non-timber crops -> 2.1.3. Agro-industry farming Timing: Ongoing Scope: Majority (50 - 90%) Severity: Slow, significant declines Stresses: 1.1 Ecosystem conversion, 1.2 Ecosystem degradation, 2.2 Species disturbance, 2.3.3 Loss of mutualism 8. Invasive and other problematic species, genes, and diseases -> 8.1 Invasive non-native/alien species/diseases -> 8.1.2. Named species - Apis mellifera Timing: Ongoing Scope: Minority (<50%) Severity: Slow, significant declines Stresses: 2.3.2 Competition 9. Pollution -> 9.3 Agricultural and forestry effluents -> 9.3.3 Herbicides and Pesticides Timing: Ongoing Scope: Minority (<50%) Severity: Slow, significant declines Stresses: 2.1 Species mortality, 2.2 Species disturbance, 2.3.7 Reduced reproductive success 11. Climate change & severe weather -> 11.1. Habitat shifting & alteration Timing: Ongoing Scope: Minority(<50%) Severity: Slow, significant declines Stresses: 1.1 Ecosystem conversion, 1.2 Ecosystem degradation, 1.3 Indirect ecosystem effects. 2.2 Species disturbance, 2.3.3 Loss of mutualism 11. Climate change & severe weather -> 11.2.Droughts Timing: Ongoing Scope: Minority (<50 %) Severity: Slow, significant declines Stresses: 1.1 Ecosystem conversion, 1.2 Ecosystem degradation, 1.3 Indirect ecosystem effects. 2.2 Species disturbance, 2.3.3 Loss of mutualism 11. Climate change & severe weather -> 11.3.Temperature extremes Timing: Ongoing Scope: Minority (<50 %) Severity: Slow, significant declines Stresses: 1.1 Ecosystem conversion, 1.2 Ecosystem degradation, 1.3 Indirect ecosystem effects. 2.2 Species disturbance, 2.3.3 Loss of mutualism Conservation Actions Conservation needs No known conservation actions are in place for this species. Protected/Managed area comment: Observations of this species are known from National Park Service land, but this does not confer any specific protections to the species. Management comment: Specific conservation needs for this species have not been identified. Due to the importance of supporting wild bee populations for pollination services, general conservation practices are recommended including, restoring, creating, and preserving natural high-quality habitats to include suitable forage and nesting sites; limiting pesticide use on or near suitable habitat, particularly during the adult bee’s flight period; promoting farming and urban practices that increase pollinator-friendly plants in margin space; minimizing exposure of wild bees to diseases transferred from managed bees; and lastly, avoiding honey bee introduction to high-quality native bee habitat. Conservation Actions Needed 1. Land/water protection -> 1.2. Resource & habitat protection 2. Land/water management -> 2.3. Habitat & natural process restoration 4. Education & awareness -> 4.3. Awareness & communications 5. Law & policy -> 5.2. Policies and regulations Research needs Research need comment: More information is needed about the population status, population trend, existing threats, range limits, habitat, and ecology of this species. Surveys targeting this species are needed throughout its range to determine its persistence throughout its historic range. Research Needed 1. Research -> 1.2. Population size, distribution & trends 1.3. Life History and Ecology 1.5. Threats 1.6 Conservation actions 3. Monitoring -> 3.1. Population trends 3.4. Habitat trends Assessment Date of assessment (month-day-year): 3/20/2025 Assessors names (use * to indicate primary assessor, typically the participant with most experience/knowledge of the species): Saff Killingsworth Reviewer(s): Contributors(s): For a full list of the 162 institutions that contributed to the Chesshire et al. dataset, please see Chesshire et al. 2023, S1. Facilitator(s) and compiler(s): Paige R. Chesshire, Erica E. Fischer, Nicolas J. Dowdy, Terry L. Griswold, Alice C. Hughes, Michael C. Orr, John S. Ascher, Laura M. Guzman, Keng-Lou James Hung, Neil S. Cobb and Lindsie M. McCabe Red List Category and Criteria: Rank/Criteria Justification: Andrena cragini is a solitary bee known from just 25 observations. It occurs in the central United States, from Kansas north to North Dakota and Minnesota. Using all observations, the extent of occurrence is 737,590 km2. The species has not been observed anywhere in its range since 2012. It is not clear if the species is extant throughout its entire range. The species is a dietary specialist that visits plants from the genus Amorpha (Fabaceae) for pollen, and occurs in the midwestern United States grasslands, which have experienced significant degradation over the last two hundred years. Across the range of the species, impacts from agricultural conversion, fragmentation, and exposure to pesticides have been observed. These threats may be acting on the species at local levels. More information is needed to determine if this species is extant throughout its entire range, to assess its population status, and the degree to which threats are acting on the species. RANK SENTENCE. Rank reasons This species is a solitary bee that occurs in the midwestern United states. Using all verified records of the species, the range extent is 737,590 km2. This species occurs in Midwest grasslands, which have experienced significant degradation over the last two hundred years . It is a dietary specialist and forages from the genus Amorpha (Fabaceae). Across the range of the species, impacts from pesticide exposure, agricultural conversion, and fragmentation have been observed. These threats may be acting on the species at local levels. Number of localities, specific threats, projected decline. Therefore, this species is likely/unlikely to be threatened with extinction at this time. NatureServe Specific Text (NOT OTHERWISE INCLUDED IN ABOVE TEXT): For Rank Calculator: 1. Element occurrences (using separation distance of 5,000 m): 2 (A) 1. Estimated Number of Element Occurrences Comments: Using all records from the last 30 years (since 1995), this species is known from at just two occurrences using a 5 km separation distance. 2. Population size: Unknown 3. Viability/Ecological integrity (choose one) 1. Number of occurrences with good viability/ecological integrity: Unknown 2. Percent of area occupied (For Species with Known AOO): N/A 4. Environmental Specificity: B. Narrow. Specialist or community with key requirements common. 1. Environmental specificity comments: This species is a dietary specialist, using pollen from the plant genus Amorpha (Fabaceae), which likely restricts its distribution and phenology. 5. Intrinsic Vulnerability: B. Moderately vulnerable 1. Intrinsic vulnerability comments: Andrena have been reported to have low reproductive output because of the short adult life span, and a low rate of brood cell provisioning (reviewed in Danforth et al. 2019). 6. Trend 1. Short Term Trend: Unknown 2. Comments: Abundance estimates and population trends are not known for this species. 3. Long Term Trend: Unknown 4. Comments: Abundance estimates and population trends are not known for this species. For Biotics Global Element Characterization: 1. Habitat Grassland/Herbaceous 2. Food Habits 1. Adult: nectarivore 2. Immature: nectarivore Literature References: Brown, Mark J. F., and Robert J. Paxton. 2009. “The Conservation of Bees: A Global Perspective.” Apidologie 40 (3): 410–16. Cane, James H., and Byron G. Love. 2021. “Hygroscopic Larval Provisions of Bees Absorb Soil Water Vapor and Release Liquefied Nutrients.” Apidologie 52 (6): 1002–16. Cane, J. H. 1981. “Dufour’s Gland Secretion in the Cell Linings of Bees (Hymenoptera: Apoidea).” Journal of Chemical Ecology 7 (2): 403–10. Chesshire, Paige R., Erica E. Fischer, Nicolas J. Dowdy, Terry L. Griswold, Alice C. Hughes, Michael C. Orr, John S. Ascher, et al. 2023. “Completeness Analysis for over 3000 United States Bee Species Identifies Persistent Data Gap.” Ecography, February. https://doi.org/10.1111/ecog.06584. Danforth, Bryan N., Robert L. Minckley, John L. Neff, and Frances Fawcett. 2019. The Solitary Bees: Biology, Evolution, Conservation. Princeton University Press. Grab, Heather, Michael G. Branstetter, Nolan Amon, Katherine R. Urban-Mead, Mia G. Park, Jason Gibbs, Eleanor J. Blitzer, Katja Poveda, Greg Loeb, and Bryan N. Danforth. 2019. “Agriculturally Dominated Landscapes Reduce Bee Phylogenetic Diversity and Pollination Services.” Science 363 (6424): 282–84. LaBerge, Wallace E. 1977. “A Revision of the Bees of the Genus Andrena of the Western Hemisphere. Part VIII. Subgenera Thysandrena, Dasyandrena, Psammandrena, Rhacandrena, Euandrena, Oxyandrena.” Transactions of the American Entomological Society 103 (1): 1–143. Michener, Charles Duncan. 2007. The Bees of the World. Vol. 1. JHU Press. Olynyk, Marika, A. Richard Westwood, and Nicola Koper. 2021. “Effects of Natural Habitat Loss and Edge Effects on Wild Bees and Pollination Services in Remnant Prairies.” Environmental Entomology 50 (3): 732–43. Packer, Laurence, Amro Zayed, Jennifer C. Grixti, Luisa Ruz, Robin E. Owen, Felipe Vivallo, and Haroldo Toro. 2005. “Conservation Genetics of Potentially Endangered Mutualisms: Reduced Levels of Genetic Variation in Specialist versus Generalist Bees.” Conservation Biology: The Journal of the Society for Conservation Biology 19 (1): 195–202. Potts, Simon G., Jacobus C. Biesmeijer, Claire Kremen, Peter Neumann, Oliver Schweiger, and William E. Kunin. 2010. “Global Pollinator Declines: Trends, Impacts and Drivers.” Trends in Ecology & Evolution 25 (6): 345–53. Raven, Peter H., and David L. Wagner. 2021. “Agricultural Intensification and Climate Change Are Rapidly Decreasing Insect Biodiversity.” Proceedings of the National Academy of Sciences of the United States of America 118 (2). https://doi.org/10.1073/pnas.2002548117. Roberts, Stuart, Simon Potts, Koos Biesmeijer, Michael Kuhlmann, William Kunin, and Ralf Ohlemüller. 2011. “Assessing Continental-Scale Risks for Generalist and Specialist Pollinating Bee Species under Climate Change.” BioRisk : Biodiversity & Ecosystem Risk Assessment 6 (December):1–18. Rousseau, Josée S., S. Hollis Woodard, Sarina Jepsen, Brianne Du Clos, Alison Johnston, Bryan N. Danforth, and Amanda D. Rodewald. 2024. “Advancing Bee Conservation in the US: Gaps and Opportunities in Data Collection and Reporting.” Frontiers in Ecology and Evolution 12. https://doi.org/10.3389/fevo.2024.1346795. Samson, Fred, and Fritz Knopf. 1994. “Prairie Conservation in North America.” Bioscience 44 (6): 418–21. Tscharntke, Teja, Alexandra M. Klein, Andreas Kruess, Ingolf Steffan-Dewenter, and Carsten Thies. 2005. “Landscape Perspectives on Agricultural Intensification and Biodiversity Ecosystem Service Management.” Ecology Letters 8 (8): 857–74. Williams, A. Park, B. I. Cook, and S. E. Smerdon. 2022. “Rapid Intensification of the Emerging Southwestern North American Megadrought in 2020–2021.” Nature Climate Change 12 (3): 232–34. Williams, N. M., Elizabeth E. Crone, T’ai H. Roulston, Robert L. Minckley, Laurence Packer, and Simon G. Potts. 2010. “Ecological and Life-History Traits Predict Bee Species Responses to Environmental Disturbances.” Biological Conservation 143 (10): 2280–91. Wojcik, Victoria A., Lora A. Morandin, Laurie Davies Adams, and Kelly E. Rourke. 2018. “Floral Resource Competition Between Honey Bees and Wild Bees: Is There Clear Evidence and Can We Guide Management and Conservation?” Environmental Entomology 47 (4): 822–33.

Conservation needs No known conservation actions are in place for this species. Protected/Managed area comment: Observations of this species are known from National Park Service land, but this does not confer any specific protections to the species. Management comment: Specific conservation needs for this species have not been identified. Due to the importance of supporting wild bee populations for pollination services, general conservation practices are recommended including, restoring, creating, and preserving natural high-quality habitats to include suitable forage and nesting sites; limiting pesticide use on or near suitable habitat, particularly during the adult bee’s flight period; promoting farming and urban practices that increase pollinator-friendly plants in margin space; minimizing exposure of wild bees to diseases transferred from managed bees; and lastly, avoiding honey bee introduction to high-quality native bee habitat.

Research need comment: More information is needed about the population status, population trend, existing threats, range limits, habitat, and ecology of this species. Surveys targeting this species are needed throughout its range to determine its persistence throughout its historic range.

(a. any taxonomic concerns about the validity of the species? b. any taxonomic revisions underway that would require a species reassessment.