Andrena crawfordi

Justification:
Andrena crawfordi is a solitary bee species that occurs in the central United States, from southern Texas north to North Dakota. Using all observations of this species the extent of occurrence is 1,643,980 km2. The species has only been recorded once since 2012, although this may be due to limited sampling or digitization efforts. The species is a dietary specialist, primarily visiting plants from the genus Pyrropappus (Asteraceae) for pollen. It occurs in grassland, shrubland, pastureland, and agricultural areas. Across the range of the species, impacts from climate change and drought, habitat loss and degradation, and exposure to pesticides have been observed. These threats may be acting on the species at local levels. More information is needed to determine the population trend of the species, and to assess the degree to which threats are acting on the population. Because the species is relatively widespread and occurs in several different habitat types, it is unlikely that it is threatened with extinction at this time. As such, it is assessed as Least Concern for now.

Food habits comment: Andrena crawfordi is a dietary specialist, and collects pollen from the Asteraceae tribe Cichoriae, with most females collected carrying exclusively pollen from the genus Pyrropappus (LaBerge 1967). Habitat comment: This species has been recorded in grassland, shrubland, pastureland, and agricultural areas, between 7 and 914 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). This species has been recorded with rates of parasitism by Stylops crawfordi as high as 35% at some sites (Jones and Jones 1981; Balzer and Davis 2020). It is unclear what effect this has on the population range-wide. Phenology comment: Records of this species come from March through May, with most records from April (Chesshire et al. 2023; LaBerge 1967). Adults are assumed to emerge annually (Danforth et al. 2019).

Threat comments: Certain aspects of this species' biology may make it more vulnerable to some threats. Andrena crawfordi 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: 1. Residential & commercial development -> 1.1. Housing & urban areas 1. Residential & commercial development -> 1.2. Commercial & industrial areas 2. Agriculture & aquaculture -> 2.1. Annual & perennial non-timber crops -> 2.1.3. Agro-industry farming 7. Natural system modifications -> 7.1. Fire & fire suppression -> 7.1.1.Increase in fire frequency/intensity 7. Natural system modifications -> 7.1. Fire & fire suppression -> 7.1.2. Suppression in fire frequency/intensity 8. Invasive and other problematic species, genes, and diseases -> 8.1 Invasive non-native/alien species/diseases -> 8.1.2. Named species 9. Pollution -> 9.3 Agricultural and forestry effluents -> 9.3.3 Herbicides and Pesticides 11. Climate change & severe weather -> 11.1. Habitat shifting & alteration 11. Climate change & severe weather -> 11.2.Droughts 11. Climate change & severe weather -> 11.3.Temperature extremes Conservation Actions Conservation needs No known conservation actions are in place for this species. Protected/Managed area comment:There are no observations of this species from federally protected land. Most records of this species come from Texas, where there is little public land. 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): 3-21-2025 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: Least Concern Justification: Andrena crawfordi is a solitary bee species that occurs in the central United States, from southern Texas north to North Dakota. Using all observations of this species the extent of occurrence is 1,643,980 km2. The species has only been recorded once since 2012, although this may be due to limited sampling or digitization efforts. The species is a dietary specialist, primarily visiting plants from the genus Pyrropappus (Asteraceae) for pollen. It occurs in grassland, shrubland, pastureland, and agricultural areas. Across the range of the species, impacts from climate change and drought, habitat loss and degradation, and exposure to pesticides have been observed. These threats may be acting on the species at local levels. More information is needed to determine the population trend of the species, and to assess the degree to which threats are acting on the population. Because the species is relatively widespread and occurs in several different habitat types, it is unlikely that it is threatened with extinction at this time. As such, it is assessed as Least Concern for now. Rank reasons This species is a solitary bee that occurs in the central United States, from south Texas north to North Dakota. Using all verified records of the species, the range extent is 1,643,980km2. This species occurs in grasslands, shrublands, pasturelands and agricultural areas. It is a dietary specialist and forages from the genus Pyrropappus. Across the range of the species, impacts from climate change, pesticide exposure, and urbanization have been observed. These threats may be acting on the species at local levels. The species has only been recorded at three localities since 1995, although this could be due to limited sampling or digitization. More information is needed to assess the population trend of this species, and to determine the degree to which threats are acting on the species. Because this species is known from a relatively large range, and occurs in several habitat types, it is 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): 3 (A) 1. Estimated Number of Element Occurrences Comments: Using all records from the last 30 years (since 1995), this species is known from just three 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 Pyrropappus (Asteraceae), 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 Shrubland/chaparral, Grassland/Herbaceous, Cropland/Hedgerow 2. Food Habits 1. Adult: nectarivore 2. Immature: nectarivore Literature References: Balzer, Zach S., and Arthur R. Davis. 2020. “Life History Traits and Interactions of Stylops Advarians (Strepsiptera) with Its Bee Host, Andrena Milwaukeensis.” Parasitology 147 (4): 410–17. 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. Jones, D., and G. Jones. 1981. “Stylopization of Andrena Spp Hymenoptera Andrenidae by Stylops Crawfordi Strepsiptera Stylopidae in Texas Usa.” Journal of the Kansas Entomological Society 54 (April):223–27. LaBerge, Wallace E. 1967. “A Revision of the Bees of the Genus Andrena of the Western Hemisphere. Part I. Callandrena. (Hymenoptera: Andrenidae).” Bulletin of the University of Nebraska State Museum 7 (October). http://digitalcommons.unl.edu/museumbulletin. Michener, Charles Duncan. 2007. The Bees of the World. Vol. 1. JHU Press. 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. 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:There are no observations of this species from federally protected land. Most records of this species come from Texas, where there is little public land. 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.