Andrena deserticola

Justification:
Andrena deserticola is a solitary bee that occurs in southern California, United States. Although the revision of this species included reference to over 200 observations of this species, the available digitized specimen records numbered only 20. Using all available digitized data, the extent of occurrence is 52,409 km2. This species has not been observed since 1972, and it is unclear if it is still extant throughout its entire range. This species is known from 15 or fewer locations, if threats act independently on each documented locality. The species is a dietary specialist that visits plants from the family Camissonia (Onagraceae) for pollen. It occurs in desert shrublands. Across the range of the species, impacts from climate change and drought, habitat degradation and loss, and exposure to pesticides have been observed. These threats may be acting on the species at local levels. This species may be particularly vulnerable to drought, due to its dietary restriction to just one genus of spring blooming annual plant, the quantity and quality of which may be impacted by limited winter rainfall. Because this species is known from a narrow distribution and limited locations, but does not meet the thresholds to be considered Vulnerable under criterion B, it is assessed as Near Threatened for now. This rank should be adjusted should additional information contribute to a wider distribution, or if comprehensive surveys determine that this species is indeed absent from some or all of its range

Food habits comment: Andrena deserticola is a dietary specialist, and collects pollen from plants in the genus Camissonia (Onagraceae), primarily Camissonia campestris (LaBerge and Thorp 2005). Habitat comment: This species has been recorded in desert shrublands of inland California, between 337 and 1180 m. Reproduction comment: This species has been observed nesting in small aggregations of approximately a dozen nests. Nest entrances are vertical and about 60 m deep. Nest observations were made on the alluvial fan of a canyon near a wash (LaBerge and Thorp 2005). 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). Strepsipteran parasites from the genus Stylops have been observed in this species (LaBerge and Thorp 2005). Phenology comment: Records of this species come from March through July, with most records from March through May (Chesshire et al. 2023; LaBerge and Thorp 2005). Adults are assumed to emerge annually (Danforth et al. 2019).

Threat comments: Specific threats to this species have not been identified. It may be impacted by long term drought. Since 2000, the Southwest U.S. has seen the worst drought in 1200 years (Williams, Cook, and Smerdon 2022). Drought can reduce the abundance of flowering plants on a landscape scale, and also reduce pollen and nectar quality (Wilson Rankin, Barney, and Lozano 2020). Drought conditions have been shown to reduce the diversity and abundance of native bees (Minckley, Roulston, and Williams 2013; Hung et al. 2021). Because Andrena deserticola has a short adult life stage, emerges in spring, and appears to be a narrow pollen specialist of the plant Camissonia which blooms in response to winter rain, it may be at further risk from winter droughts within its range. Certain aspects of this species' biology may make it more vulnerable to some threats. Andrena deserticola 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: 1. Residential & commercial development -> 1.1. Housing & urban areas Timing: Ongoing Scope: Minority (<50%) Severity: Slow, significant declines 1. Residential & commercial development -> 1.2. Commercial & industrial areas Timing: Ongoing Scope: Minority (<50%) Severity: Slow, significant declines 7. Natural system modifications -> 7.1. Fire & fire suppression -> 7.1.1.Increase in fire frequency/intensity Timing: Ongoing Majority: 50 - 90% Severity: Slow, significant declines 8. Invasive and other problematic species, genes, and diseases -> 8.1 Invasive non-native/alien species/diseases -> 8.1.2. Named species Timing: Ongoing Scope: Minority (<50%) Severity: Slow, significant declines 9. Pollution -> 9.3 Agricultural and forestry effluents -> 9.3.3 Herbicides and Pesticides Timing: Ongoing Scope: Minority (<50%) Severity: Causing/could cause fluctuations 11. Climate change & severe weather -> 11.1. Habitat shifting & alteration Timing: Ongoing Majority: 50 - 90% Severity: Slow, significant declines 11. Climate change & severe weather -> 11.2.Droughts Timing: Ongoing Majority: 50 - 90% Severity: Slow, significant declines 11. Climate change & severe weather -> 11.3.Temperature extremes Timing: Ongoing Majority: 50 - 90% Severity: Slow, significant declines 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 Bureau of Land Management (BLM) and National Park Service landland, 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): 4-3-2025 Assessors names (use * to indicate primary assessor, typically the participant with most experience/knowledge of the species): 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: Near Threatened Justification: Andrena deserticola is a solitary bee that occurs in southern California, United States. Although the revision of this species included reference to over 200 observations of this species, the available digitized specimen records numbered only 20. Using all available digitized data, the extent of occurrence is 52,409 km2. This species has not been observed since 1972, and it is unclear if it is still extant throughout its entire range. This species is known from 15 or fewer locations, if threats act independently on each documented locality. The species is a dietary specialist that visits plants from the family Camissonia (Onagraceae) for pollen. It occurs in desert shrublands. Across the range of the species, impacts from climate change and drought, habitat degradation and loss, and exposure to pesticides have been observed. These threats may be acting on the species at local levels. This species may be particularly vulnerable to drought, due to its dietary restriction to just one genus of spring blooming annual plant, the quantity and quality of which may be impacted by limited winter rainfall. Because this species is known from a narrow distribution and limited locations, but does not meet the thresholds to be considered Vulnerable under criterion B, it is assessed as Near Threatened for now. This rank should be adjusted should additional information contribute to a wider distribution, or if comprehensive surveys determine that this species is indeed absent from some or all of its range Rank reasons This species is a solitary bee that occurs in southern California. Using all verified records of the species, the range extent is 52,409 km2. This species occurs in desert shrublands. It is a dietary specialist and collects pollen from the plant genus Camissonia (Onagraceae) to feed offspring. 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. This species has not been observed since 1972, and it is unclear if the species is still extant throughout its range. It is only known from 15 localities. Because it is relatively narrowly distributed, and has not been observed for over 50 years, it is assumed to be rare if still extant, and therefore faces some extinction risk. NatureServe Specific Text (NOT OTHERWISE INCLUDED IN ABOVE TEXT): For Rank Calculator: 1. Element occurrences (using separation distance of 5,000 m): 0 1. Estimated Number of Element Occurrences Comments: Using all records from the last 30 years (since 1995), this species is known from zero occurrences using a 5 km separation distance. It is only known from 15 element occurrences overall. 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 Camissonia (Onagraceae), 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, Desert 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. Hung, Keng-Lou James, Sara S. Sandoval, John S. Ascher, and David A. Holway. 2021. “Joint Impacts of Drought and Habitat Fragmentation on Native Bee Assemblages in a California Biodiversity Hotspot.” Insects 12 (2). https://doi.org/10.3390/insects12020135. LaBerge, Wallace E., and Robbin W. Thorp. 2005. “A Revision of the Bees of the Genus Andrena of the Western Hemisphere.” Illinois Natural History Survey Bulletin 37 (1-6): 1–64. Michener, Charles Duncan. 2007. The Bees of the World. Vol. 1. JHU Press. Minckley, Robert L., T’ai H. Roulston, and Neal M. Williams. 2013. “Resource Assurance Predicts Specialist and Generalist Bee Activity in Drought.” Proceedings. Biological Sciences / The Royal Society 280 (1759): 20122703. 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. Wilson Rankin, Erin E., Sarah K. Barney, and Giselle E. Lozano. 2020. “Reduced Water Negatively Impacts Social Bee Survival and Productivity Via Shifts in Floral Nutrition.” Journal of Insect Science 20 (5). https://doi.org/10.1093/jisesa/ieaa114. 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 Bureau of Land Management (BLM) and National Park Service landland, 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.