Andrena levipes

Justification:
Andrena levipes is a dietary generalist, spring-active bee species known from the Western United States. Most records of this bee come from California, although it is also reported from Oregon, Colorado, and Arizona as well. Using all known records of this species, the extent of occurrence is 1,017,568 km2. There have been only five observations of this species since 1970, coming from only two localities. Therefore, the persistence of this species throughout its entire historic range is unknown. Across the range of the species impacts from climate change, urbanization, and exposure to pesticides have been reported, and may be acting on the species at local levels. More research is needed to determine the range extent of this species, population trends, and threats. As such, it is assessed as Data Deficient.

Andrena levipes is considered to be a dietary generalist, using plants from the family Polemoniaceae (including the genera Leptosiphon and Linanthus) as a primary host, and from Asteraceae (including the genera Lasthenia and Coreopsis) as a secondary host. It has been recorded from shrublands and conifer forests of southern California mountains, the western Mojave basin, and lower montane forests of the Sierra Nevada and Klamath Mountains. 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). Records of this species come from March through June, with most records from May (LaBerge 1967; Chesshire et al. 2023). Adults are assumed to emerge annually (Danforth et al. 2019).

Threats to this species are not well understood. Certain aspects of this species' biology may make it more vulnerable to some threats. Andrena levipes 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).

No known conservation actions are in place for this species. Observations of this species are known from Bureau of Land Management (BLM) and US 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.