Andrena nubecula

The cloudy-winged mining bee is an dietary specialist that visits plants from the family Asteraceae for pollen, with foraging recorded from the genera Symphyotrichum, Solidago, and Aster (Arduser, 2010; Wood & Roberts, 2018). This species occurs in deciduous and coniferous forests, shrublands, and grasslands across many ecoregions. It has also been collected from urban and suburban areas. 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 & 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 May through October, with most records from July through September months (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 cloudy-winged mining bee 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 & Paxton, 2009; Grab et al., 2019; Potts et al., 2010; Raven & Wagner, 2021; Wojcik et al., 2018). 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 in Indiana and New York, U.S.

Conservation needs No known conservation actions are in place for this species. Observations of this species are known from US Fish and Wildlife, US Forest Service, Bureau of Land Management (BLM), and National Park 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.