Andrena beameri

Justification:
Andrena beameri is a solitary bee species that occurs in tallgrass prairies in Kansas, Missouri, Oklahoma, and Arkansas, United States. It is a narrow dietary specialist, primarily using pollen from just one genus (Asteraceae: Coreopsis). Using all observations of the species, the extent of occurrence is 170,319 km2. Using all observations, the area of occupancy is 104 km2. Although area of occupancy is not typically reliable for invertebrate species where there has been limited search effort throughout the range of species, the narrow habitat specialization and dietary specialization of this species significantly restrict the suitable habitat for this species. This species probably occurs in 20 locations, made up of occurrences separated by 5 km, which is likely further than this species is able to disperse. These locations are all threatened by habitat loss and modification, including fragmentation, which likely limited the abundance of this species and may contribute to reduced genetic diversity due to the inability of this species to move between fragments. More information is needed to assess the extent to which this species occurs in all suitable habitat fragments, and the degree to which localized threats are acting on the species. Because of the small AOO and limited number of locations, this species is assessed as Near Threatened at this time.

Distribution

Population

Habitats and Ecology

Andrena beameri is a dietary specialist species that visits plants from the tribe Heliantheae (Asteraceae) for pollen (Larkin, Neff, and Simpson 2008), with an apparent preference for the genus Coreopsis, including C. laneceolota, plamata, and grandiflora (M. Arduser, pers comm. with S. Killingsworth 10 May 2024). The species has also been recorded foraging on Rudbeckia (Buckles 2015; Schuette 2016), Verbesina (J. Hung, pers comm. with S. Killingsworth 16 May 2024), and Echinacea (M. Arduser, pers comm. with S. Killingsworth 10 May 2024). Observations of this species come from remnant tallgrass prairies of southwestern Missouri and Arkansas, including from prairie remnants as small as 0.5 hectares (Schuette 2016). It can also be found in igneous and calcareous Ozark glades (M. Arduser, pers. comm. with S. Killingsworth 10 May 2024). Land managers and researchers who work with the species have not detected the species in prairie plantings or reconstructions, except for when these restoration projects are adjacent to remnant prairie (M. Arduser, pers comm. with S. Killingsworth 10 May 2024). 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 May and June (Chesshire et al. 2023). Adults are assumed to emerge annually (Danforth et al. 2019).

Habitat Types

Use and Trade

Threats

This species is threatened by habitat loss and modification of the tallgrass prairie ecosystem it relies on, which has seen major habitat loss and modification in the last 200 years (Samson and Knopf 1994). 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. The remaining prairie ecosystem within the range of the species is made up by habitat fragments of varying size. Habitat loss due to fragmentation and also increased habitat disturbance via roads have been shown to negatively influence bee abundance in prairie ecosystems (Olynyk, Westwood, and Koper 2021). Fragmentation can also decrease plant diversity, contributing to reduced bee abundance (Winfree et al. 2009; Glaum et al. 2017; Theodorou et al. 2020). Lack of connectivity between habitat fragments can contribute to reduced genetic diversity, as bees may not be able to travel between habitat fragments to mate (Tscharntke et al. 2005). Although there is conservation attention to tallgrass prairies and their restoration, some restoration activities may have negative impacts on Andrena beameri if not carried out with consideration to the species. Early prescribed fire, mowing, or haying of private prairie parcels may remove the host plants required by the bee, and should be carried out after the May/June flight period of the species. Certain aspects of this species' biology may make it more vulnerable to some threats. Andrena beameri 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 level in one area where it occurs. This species has been evaluated as Vulnerable in Missouri.

Conservation Actions

Conservation needs Andrena beameri benefits from community-level habitat conservation actions employed by the Missouri Department of Conservation, the Missouri Department of Natural Resources, the Missouri Prairie Foundation, and the Nature Conservancy. These agencies and organizations employ conservation and restoration actions, such as prescribed fire, that maintain and restore the quality of prairie remnants to the benefit of Andrena beameri, as well as other insect species that occur there. This species has been observed from National Park Service land and U.S. National Forest Service land as well as two Oklahoma State Wildlife Management Areas (Pushmataha and Atoka), and a number of conservation lands in Missouri, including the Bryant Creek, Johnson Shut-Ins, and Roaring River State Parks, The Shaw Nature Preserve, Drover’s Prairie Conservation Area, the WahKonTah Prairie, Friendly Prairie, and Paintbrush Prairie. This does not confer any specific protections to the species. This species is considered a Species of Greatest Conservation Need in the State Wildlife Action Plan of Missouri (Missouri Department of Conservation 2015). Although there are no conservation actions in place that specifically target this species, a number of conservation and restoration practices in place for the benefit of tallgrass prairie ecosystems likely benefit this species. Within Missouri, existing populations are being tracked, and occurrences of the species are recorded in the state Heritage Database (A. Morphew, pers. comm. with S. Killingsworth 26 June 2024). Further research is needed to determine the overall size of the population, the extent to which it occurs in existing prairie remnants, and to identify trends, existing threats, and conservation actions that would benefit the species. Conservation actions for this species should include protecting tallgrass prairie habitat where it occurs, including even small parcels, and populations of Coreopsis should be protected. Habitat restoration actions, such as prescribed fire and mowing, should be delayed until the flight period of Andrena beameri has concluded. Prescribed fire should be applied in the dormant season, and haying and mowing should be done in small units relative to the size of the prairie remnant to minimize impacts to A. beameri and other species of insects that are dependent on remnant prairies. 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.

Code	Threat	Timing	Scope	Severity
1	Residential & commercial development - 1.2. Commercial & industrial areas	Ongoing	Minority (<50%)	Slow, significant declines
1.1	Residential & commercial development - Housing & urban areas	Ongoing	Minority (<50%)	Slow, significant declines
1.2	Residential & commercial development - Commercial & industrial areas	Ongoing	Minority (<50%)	Slow, significant declines
2	Agriculture and aquaculture - Livestock farming and ranching -> Agro-industry grazing, ranching, or farming	Ongoing	Majority (50 - 90 %)	Slow, significant declines
2.1.3	Agriculture & aquaculture - Agro-industry farming	Ongoing	Majority (50 - 90 %)	Slow, significant declines
7	Natural system modifications - 7.1. Fire & fire suppression -> 7.1.2. Suppression in fire frequency/intensity	Ongoing	Minority (<50%)	Causing/Could cause fluctuations
7.1.1	Natural system modifications - Increase in fire frequency/intensity	Ongoing	Minority (<50%)	Causing/Could cause fluctuations
8	Invasive and other problematic species, genes, and diseases - 8.1 Invasive non-native/alien species/diseases -> 8.1.2. Named species	Ongoing	Minority (<50%)	Slow, significant declines
8.1.2	Invasive and other problematic species, genes, and diseases - Named species	Ongoing	Minority (<50%)	Slow, significant declines
9	Pollution - 9.3 Agricultural and forestry effluents -> 9.3.3 Herbicides and Pesticides	Ongoing	Minority (<50%)	Slow, significant declines
9.3.3	Pollution - Herbicides and Pesticides	Ongoing	Minority (<50%)	Slow, significant declines
11	Climate change & severe weather - 11.3.Temperature extremes	Ongoing	Minority (<50%)	Slow, significant declines
11.1	Climate change & severe weather - Habitat shifting & alteration	Ongoing	Minority (<50%)	Slow, significant declines
11.2	Climate change & severe weather - Droughts	Ongoing	Minority (<50%)	Slow, significant declines
11.3	Climate change & severe weather - Temperature extremes	Ongoing	Minority (<50%)	Slow, significant declines

Assessment