Andrena canadensis

Justification:
The Canadian miner bee (Andrena canandensis) is a pollen specialist bee species known from approximately 470 records. It occurs across most of the United States, with a majority of records from the Northeast and the Great Lakes regions. Using all known records of the species, the extent of occurrence is 6,226,241 km2. However, there have been limited recent records in the western part of the entire range. This is likely an effect of reduced search effort in these regions. However, the persistence of this species throughout its entire range is unknown. Within the range of the species, climate change impacts, increased urbanization and agricultural development have been observed, so it is possible that localized threats are acting on this species. Because this species is widespread and occurs in many different habitats, it may not be threatened with extinction at this time, but more information is needed about the persistence of this species throughout its entire range. For now, it is assessed as Least Concern.

The Canadian miner bee is a pollen specialist that visits plants in the family Asteraceae for pollen, especially the genera Solidago and Symphyotrichum (Stevens 1949; Wood and Roberts 2018). In a study in low-bush blueberry production areas in Maine, the species was associated with emergent wetland habitats (Du Clos, Drummond, and Loftin 2020). The species likely nests underground like all other Andrena (Danforth et al. 2019), but nests for 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 before laying a single egg (Michener 2007). The adult flight period is August and September (Stevens 1949). Adults are assumed to emerge annually (Danforth et al. 2019). Maximum foraging distance has been estimated to be 250 - 500 meters (Du Clos, Drummond, and Loftin 2020).

Specific threats to this species have not been identified. However, certain aspects of this species' biology may make it more vulnerable to some threats. Andrena canadensis 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 oligolectic, 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 Indiana, U.S., Imperiled in New York and Vermont, and Critically Imperiled in Connecticut.

No known conservation actions are in place for this species. Observations of this species are known from Bureau of Land Management (BLM), United States Forest Service, Fish and Wildlife Service, and 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 better understand 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.

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