Andrena bisalicis

Justification:
Andrena bisalicis is a solitary bee that occurs across much of the eastern United States and some areas of southern Canada. Most records of the species come from the Mid-Atlantic and New England region of the United States. Using all records, the extent of occurrence is 3,359,405 km2. The species has been recorded in several forest types, and in agricultural and urban areas. It is a dietary specialist that collects pollen primarily from the genus Salix (Salicaceae), but also makes use of pollen from several other genera, including apples and blueberries. Across the range of the species, threats such as climate change, habitat degradation and loss, and exposure to pesticides have been identified, and may be acting on the species at local levels. However, because the species is widespread, occurs in many different habitat types, and has been recently observed in many parts of its range, it is not likely threatened with extinction at this time. As such, it is ranked Least Concern.

Andrena bisalicis is a dietary specialist that collects pollen from the plant genus Salix (Salicaceae) to feed its larvae, but also relies on pollen from the genus Prunus (Rosaceae) (LaBerge 1977). The species has also been recorded foraging from blueberry (Scott, Ginsberg, and Alm 2016) and apple (Park, Orr, and Danforth 2010). It occurs in a wide variety of habitats, including evergreen, deciduous, and mixed forest, agricultural areas, 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). Andrena bisalicis is one of few species that has had its pupa described (Yager and Rozen 1966). Nearly all records of this species come from March through June, with several records from August and September (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. Andrena bisalicis 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).

Conservation needs No known conservation actions are in place for this species. Observations of this species are known from US Fish and Wildlife Service, National Forest Service, 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. The species is ranked as Vulnerable in Ontario, Canada, and Illinois, New York, and Vermont, United States. 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.