Andrena asteris

Justification:
The Aster Mining Bee (Andrena asteris) is a dietary specialist solitary bee that occurs in the eastern United States and Southern Canada. Using all records of the species, its extent of occurrence is 3,683,844 km2. Records since 2013 are well distributed across most of the known range of the species. It occurs in low lying areas with sandy soil in grasslands, mixed and coniferous forests, woody wetlands, and in agricultural and urban areas, where it forages on plants in the family Asteraceae for pollen. Across its range, impacts from urbanization, climate change, and exposure to pesticides. These threats may be acting on the species at local levels, and the species is ranked as vulnerable in several states where it occurs. Additionally, this species may be intrinsically vulnerable due to low fecundity, host plant specialization, and nest site specificity. More information is needed to assess range wide population trends. However, it is widespread, occurs in many habitat types, and has been recently observed across much of its range. As such, it is assessed as Least Concern for now.

The Aster Mining Bee is a dietary specialist solitary bee that visits plants from the family Asteraceae, primarily from the tribe Astereae, for pollen (LaBerge 1967; Larkin, Neff, and Simpson 2008). This dietary breadth has been confirmed by pollen analysis in a study from New York, United States (Espinoza et al. 2022). This species has been recorded from grasslands, deciduous and mixed forest, woody wetlands, and agricultural and urban areas. A species distribution model generated as part of a study on the biology of this species found that the highest habitat suitability for this species is near the coast or large inland water bodies, in low elevation areas where soil sand content is high and clay content is low, with low habitat suitability at high elevations and in the southeastern United States (Espinoza et al. 2022). This species makes the deepest recorded nest of any solitary bee species in the northeast United States, with brood cells as deep as 91 cm (Espinoza et al. 2022). The nests examined had entrances that extended directly downwards through sandy soil to sandy loam, with tunnel diameter ranging from 5.5 to 6 mm. Nests contained one to five brood cells, which were located at the ends of the lateral burrows, and lined with a waxy glandular secretion (Espinoza et al. 2022) 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). Records of this species come from July through November, with most records from September and October (LaBerge 1967; Espinoza et al. 2022; Chesshire et al. 2023). Adults are assumed to emerge annually (Danforth et al. 2019). The cleptoparasite bee species, Nomada banksi, has been recorded within the nests of the Aster Mining Bee (Espinoza et al. 2022).

This species was ranked as Vulnerable using NatureServe criteria within the state of New York (White et al. 2022). The comprehensive study of Aster Mining Bee biology confirmed that certain life history traits, including its univoltine strategy, host-plant specialization, and nest biology that includes nest site specificity contribute to conservation concern for this species (Espinoza et al. 2022). Certain aspects of this species' biology may make it more vulnerable to some threats. Andrena asteris 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). This species has had its conservation status evaluated using NatureServe criteria at the U.S. state and Canadian province level in some areas where it occurs. It has been evaluated as Vulnerable in Ontario, Canada, and New York, Indiana, and Connecticut, U.S.

Conservation needs No known conservation actions are in place for this species. The Aster Mining Bee was ranked as vulnerable in an assessment of conservation statuses of New York bees (White et al. 2022). Using NatureServe criteria, it has also been ranked as vulnerable in Connecticut and Indiana, United States, and Ontario, Canada. However, this species is not yet included in the State Wildlife Action Plans (SWAPs) for the U.S. states where it occurs, meaning its conservation is not being directly addressed at the state-level. Observations of this species are known from United States Forest Service, United States Fish and Wildlife, National Park Service land, but this does not confer any specific protections to the species. Further research is needed to determine the overall size of the population and to identify trends and existing threats. 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.

Surveys targeting this species are needed throughout its range to determine its persistence throughout its historic range. More information is needed about the population status, and impact of threats on this species.

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