Andrena berkeleyi

Justification:
Andrena berkeleyi is a bee species known from the southwest quadrant of the United States. Using all known records for the species, its extent of occurrence is 1,573,613 km2. Although there are limited recent observations for this species, this may not indicate a decline or range restriction, as it has been rarely observed since its first observation in 1948, and there has not likely been sufficient search effort in its range since 2013 to be able to detect it. There is little known about the ecology and life history of this species. Although direct threats to this species have not been described, climate change, land use change, and low reproductive output may contribute to risk for this bee. More research is needed to determine the population trend, range, and threats to this species. As such, it is listed as Data Deficient.

Andrena berkeleyi is reported to be a pollen specialist within the plant family Asteraceae, specifically the genera Engelmannia, Hymenoxys, and Tetraneuris. 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 before laying a single egg (Michener 2007). Adult flight period ranges from March through August (Chesshire et al. 2023) but is probably more limited is local populations. Adult emergence time likely varies across the reported range of this species as it spans many ecoregions and climatic regimes. Adults are assumed to emerge annually (Danforth et al. 2019). Habitat:

There are no specific threats documented for Andrena berkeleyi. Certain aspects of this species' biology may make it more vulnerable to some threats. Andrena berkeleyi 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 reported to be 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).

No known conservation actions are in place for this species. Observations of this species are known from United States Forest 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.

More information is needed about the population status, range limits, habitat, and ecology of this species.

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