Andrena melanochroa

Justification:
The rose miner bee (Andrena melanochroa) is a widespread species known from across the United States and southern Canada. The species has been observed foraging from a wide variety of plants, but appears to have a strong preference for members of the family Rosaceae (Fragaria, Potentilla). Using all known records for the species, the extent of occurrence is 8,630,447 km2. Although there have been no range-wide surveys to establish population trends for the rose miner bee, the species has been reported as common in several local survey efforts. General threats impacting bees at local levels have been observed across the range of the species, including overuse of pesticides, climate change impacts, and urbanization. However, because this bee is widespread and occurs in many different habitat types, these threats are unlikely to be threatening this species with extinction at this time. As such, it is assessed as Least Concern.

The rose miner bee is a pollen generalist species with a strong preference for pollen from the plant family Rosaceae, mostly from the genera Fragaria and Potentilla (Ribble 1968). It has been recorded from wide ranging habitats including temperate forests, pine barrens, grasslands, Rocky Mountain forests, cold deserts, marine forests of the western US, and Sierra Nevada foothills. In the southern part of the range, the species has been collected mostly from mountainous areas (Ribble 1968). 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 March through July, with most observations from May and June (Ribble 1968; Chesshire et al. 2023). Adults are assumed to emerge annually (Danforth et al. 2019). Some parasitism has been reported in this species. Three individual specimens were parasitized by Stylops (Strepsiptera), and another was parasitized by an unidentified triungulin larvae (Ribble 1968). These parasites are not known to contribute to extinction risk for the species.

Specific threats to this species are not well understood. Certain aspects of this species' biology may make it more vulnerable to some threats. Andrena melanochroa 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 appears to have a strong dietary preferences for a limited suite of species. Although this species is not a dietary specialist, it may be subject to higher risk of extinction due to reduced preferred 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, 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). This species has had its conservation status evaluated using NatureServe criteria at the U.S. state and Canadian province level in some areas where it occurs. It has been evaluated as Vulnerable in British Columbia and Ontario, Canada, and Vermont, U.S., and Imperiled in New York.

No known conservation actions are in place for this species. Observations of this species are known from Bureau of Land Management (BLM), U.S Forest Service, U.S. 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 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.