Andrena agoseridis

Justification:
Andrena agoseridis is a pollen specialist solitary bee that occurs in southern California. It has been recorded in the deserts and shrublands of the Mojave Basin and foothills of the southern California mountains. Using all known records of the species, the extent of occurrence is 209,025 km2. However, the species has not been recorded anywhere within the EOO since 1973, so it is unclear if the species is extant. Across the range of the species, impacts from climate change, drought, and urbanization have been observed, and these may be acting on the species. More information is needed to determine whether or not this species has been truly extirpated from its range. As such it is assessed as Data Deficient for now.

This species may be a dietary specialist, collecting pollen from members of the plant family Asteraceae, primarily Agoseris heterophylla and Anisocoma acaulis (Thorp 1969). Females reportedly forage between from early morning to late morning (Thorp 1969). The species has been recorded in the deserts and shrublands of the western Mojave basin and the foothills of the southern California Mountains. Nests of this species were located on a bare road-bed in hard packed sand. Nest entrances were surrounded by a small tumulus, and nests measured between 15 and 20 cm deep (Thorp 1969). Nest cells were located at the ends of the lateral burrows, which are typically lined with a waxy Dufour’s gland secretion (Thorp 1969) 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 on which they lay a single egg (Michener 2007). Records of this species come from March through May (Thorp 1969; Chesshire et al. 2023). Adults are assumed to emerge annually (Danforth et al. 2019). *

Since 2000, the Southwest U.S. has seen the worst drought in 1200 years (A. P. 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). Additionally, many observations of this species come from urban edges, and their habitat may be at risk of modification or loss due to suburban sprawl. Certain aspects of this species' biology may make it more vulnerable to some threats. Andrena agoseridis 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 (N. M. Williams et al. 2010). This species is a dietary specialist, 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).

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