Andrena andrenoides

Justification:
The Colourful Willow Miner Bee (Andrena andrenoides) is a solitary bee that occurs across most of the United States and parts of Southern Canada. Most records of this species come from the Great Plains region. Using all records, the extent of occurrence is 7,707,508 km2. There are limited recent records of this species, which come from Wyoming, North Dakota, and Minnesota. This species is a dietary specialist that visits members of the genus Salix (Salicaceae) for pollen. Across the range of the species, impacts from climate change and urbanization have been observed. The Great Plains has seen major impacts from habitat loss and modification, and pesticide use in this agriculturally dominated region may present major threats to this species. More information is needed on the population trends of this species. However, because this species is widespread and occurs in many different habitat types, it is unlikely that it is threatened with extinction at this time. As such, it is assessed as Least Concern for now.

The Colourful Willow Miner Bee is a dietary specialist that visits plants from the genus Salix (Salicaceae) for pollen (LaBerge and Ribble 1972). This species has been recorded in grasslands, forests, wetland edges, and agricultural and urban 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 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 records from April and May (LaBerge and Ribble 1972; Chesshire et al. 2023). Adults are assumed to emerge annually (Danforth et al. 2019).

Specific threats to this species have not been investigated. This species occurs in the Great Plains region of the United States, a landscape that has seen major habitat loss and modification in the last 200 years (Samson and Knopf 1994), including in the limited riparian areas that occur there (Hoover et al. 2001; Ripple and Beschta 2007). Much of this modification has resulted from agricultural conversion, which has both altered the plant community composition, and increased the potential for exposure to pesticides at levels lethal for bees. Certain aspects of this species' biology may make it more vulnerable to some threats. Andrena andrenoides 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 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). 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 Indiana U.S., and as Possibly Extirpated in New York, U.S.

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.