Andrena arabis

Justification:
The mustard miner bee (Andrena arabis) is a spring-active, widespread bee that occurs across most of the northeast United States. The extent of occurrence for this species is 1,155,438 km2. The species is a pollen specialist, visiting plants from only the plant family Brassicaceae. Although its dietary breadth is narrow, it has been recorded foraging on cosmopolitan weedy species in this plant family, as it is known to occur in developed areas. Within the range of the species, climate change impacts and urbanization are intensifying, so it is possible that localized threats are acting on this species. However, because the species is widespread, locally common, and occurs in different ecoregions and developed areas, it is unlikely that it is threatened with extinction at this time. Therefore, it is assessed as Least Concern.

The mustard miner bee is a pollen specialist species within the plant family Brassicaceae, with floral associations from the genera Arabis, Allaria, Cardamine ((Robertson 1900; Fetridge, Ascher, and Langellotto 2008; Wood and Roberts 2018). A. arabis occurs in deciduous, closed canopy forest as well as developed land (Chesshire et al. 2023). It has been observed in residential gardens of suburban New York City (Fetridge, Ascher, and Langellotto 2008). This 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 (J. H. Cane 1981) that serves to both isolate the provision from pathogens in the surrounding soil and to regulate water uptake from the soil atmosphere (James H. Cane and Love 2021). Females provision each cell with a ball of pollen moistened with nectar before laying a single egg (Michener 2007). Adult activity period ranges from March to June, with the vast majority of observations from April and May (Chesshire et al. 2023). Adults are assumed to emerge annually (Danforth et al. 2019). Habitat:

Specific threats for this species have not been identified. However, certain aspects of this species' biology may make it more vulnerable to some threats. Andrena arabis 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 at the U.S. state and Canadian province level in some areas where it occurs using NatureServe criteria. It has been assessed as Vulnerable in Ontario, Canada and Connecticut, U.S., Imperiled in New York and Vermont, and Possibly Extirpated in North Carolina.

No known conservation actions are in place for this species. Observations of this species are known from Bureau of Land Management (BLM), US Forest Service, US Fish and Wildlife, 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?):