Andrena illinoiensis

Justification:
The tufted miner bee (Andrena illinoiensis), is a spring-active, pollen specialist bee species known from over 2,200 observations, spanning most of the United States and southern Canada. Using all known observations of this species, the extent of occurrence is 6,285,449 km2. This species uses pollen from the plant genus Salix (Salicaceae), which is common in a variety of riparian habitats. As such, this bee species is often recorded in proximity to riparian zones. Because it is a widespread species, it occurs in many different ecoregions, including deserts, grasslands, and forests. Within the range of the species, impacts from climate change, agricultural development, and urbanization have been observed, so it is possible that localized threats are acting on this species. More information is needed to assess the population trend and impacts of threats within the range of the tufted miner bee. However, because the species is widespread and occurs in many different ecoregions, it is unlikely that it is threatened at this time. Therefore, it is assessed as Least Concern for now.

The tufted miner bee is a narrow pollen specialist of plant species in the genus Salix (Salicaceae) (Ribble 1968; Wood and Roberts 2018). This species is frequently recorded in close proximity to riparian habitats. Because the species is widespread, it occurs in a wide range of ecoregions, including the Central Basin and Range, Chihuahuan Desert, Colorado Plateaus, Great Plains, and Northern Forests. 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, (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 June with the majority of records from April and May (Chesshire et al. 2023). Adults are assumed to emerge annually (Danforth et al. 2019).

Specific threats to this species have not been well defined. Drought and climate change may be particularly impactful for this species, as it depends on riparian associated Salix species as its host plant. Due to dams, river diversions, drought, and groundwater pumping, the vegetation in these riparian areas has changed dramatically in the last century, especially in the west (Ohmart 1994; Krueper 1993). Certain aspects of this species' biology may make it more vulnerable to some threats. Andrena illinoiensis 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 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 level in some areas where it occurs. It has been evaluated as Possibly Extirpated 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), National Forest Service, 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.

(a. any taxonomic concerns about the validity of the species? b. any taxonomic revisions underway that would require a species reassessment.