Andrena cerasifolii

Justification:
Andrena cerasifolii is a dietary generalist solitary bee that occurs in varied habitats of southern Canada, the western United States, and northern Mexico. It has been recorded in grasslands, shrublands, forests, agricultural areas, and urban areas. Using all known observations, the extent of occurrence is 2,403,409 km2. There are numerous records since 2013, which are well distributed across the range of the species. Although there is no rangewide study examining population trends or abundance for the species, it has been described in at least two localized studies as abundant. Across its range, Andrena cerasifolii may be facing impacts from climate change, habitat loss due to urbanization, and exposure to pesticides. These threats may be acting on the species at local levels. More information is needed to track a rangewide population trend, and assess the impacts of these threats. Because the species is widespread, occurs in many different habitat types, and has been recently recorded from many parts of its range, it is unlikely that it is threatened with extinction at this time. As such it is assessed as Least Concern.

Andrena cerasifolii is a dietary generalist, with a possible preference for plants from the following genera: Salix, Arctostaphylos, and Ceanothus (LaBerge 1986). This species has also been recorded foraging on aphid honeydew (Lehner 2022). It has been recorded in forests, shrublands, grasslands, deserts, agricultural areas, and urban environments. 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 on which they lay a single egg (Michener 2007). Records of this species come from January through September (LaBerge 1986; Chesshire et al. 2023). This distribution of collection data suggests that this species is bivoltine, with one generation emerging January through March, and a second generation emerging May and June (LaBerge 1986).

Specific threats to this species have not been identified, but this species occurs in an area that has been impacted by a major drought which likely affects the quality of habitat and availability of resources. Since 2000, the Southwest U.S. has seen the worst drought in 1200 years (Williams, Cook, and Smerdon 2022). Drought can reduce the abundance of flowering plants on a landscape scale, and also reduce pollen and nectar quality (Wilson Rankin, Barney, and Lozano 2020). Drought conditions have been shown to reduce the diversity and abundance of native bees (Minckley, Roulston, and Williams 2013; Hung et al. 2021). Certain aspects of this species' biology may make it more vulnerable to some threats. Andrena cerasifolii 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). 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).

Conservation needs 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, United States 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 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, 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.