Andrena anisochlora

Justification:
The Miner’s Lettuce Miner (Andrena anisochlora) is a solitary bee species that occurs in the western United States, from Oregon south to Southern California. There are two additional localities recorded for this species from Utah. These records are from more than 80 years old, and warrant further investigation as to their accuracy. Using only Oregon and California observations, the extent of occurrence for this species is 275,199 km2. It has been recorded from shrubland, forests, agricultural areas, and urban environments, where it is most commonly found foraging within the genus Claytonia (Montiaceae), although there are not enough foraging records available to describe the dietary breadth of this species. Across its range, impacts from urbanization, pesticide exposure, and increased wildfire frequency and severity have been reported. These threats may be acting on the species at local levels. However, because the species is fairly widespread, occurs in several habitat types, and has been recently observed across much of its range, it is unlikely that it is threatened with extinction at this time. As such, it is assessed as Least Concern.

The Miner’s Lettuce Miner has been most frequently collected in association with flowers from the genus Claytonia (Montiaceae), but there are not enough records to determine the dietary breadth of this species (LaBerge 1985). The species has been recorded from shrublands, evergreen forests, 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 February through June, with most records from March and April (LaBerge 1985; Chesshire et al. 2023). Adults are assumed to emerge annually (Danforth et al. 2019).

Certain aspects of this species' biology may make it more vulnerable to some threats. The Miner’s Lettuce Miner 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 may be 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), 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.