Andrena perpunctata

Justification:
Andrena perpunctata is a solitary bee known from the southwestern United States and Mexico. Using all records, the extent of occurrence for this species is 530,470 km2. There has only been one record of this species since 1996, and none since 2011, despite nearly five times as much recent search effort as required to detect it historically. Thus, the persistence of this species throughout its entire known range is not known. Lack of recent records may be a result of limited survey effort throughout the range of the species. There is almost no information about the ecology and habitats of this species. It has been recorded in the fall in dry, subtropical, and temperate forests as well as shrublands. Throughout the range of the species, impacts from drought and climate change have been observed, and may be acting on the species at local levels. More information is needed to understand the life history of this species, as well as its distribution, persistence throughout its known range, and population trends. As such, it is listed as data deficient for now.

There is very little available information about the habitats and ecology of this species. There is only one record of this species with floral associate information (Asteraceae: Heterotheca), therefore the dietary breadth of this species is not known. 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). This species is fall active, with records of this from August to October (Chesshire et al., 2023; Larkin et al., 2008). Adults are assumed to emerge annually (Danforth et al., 2019).

Specific threats have not been identified for this species. However, since 2000, the Southwest U.S. has seen the worst drought in 1200 years (Williams, Cook, and Smerdon 2022). Drought can reduce the abundance of flowering plants on a landscape scale, and also reduce pollen and nectar quality (Rankin, Barney, and Lozano 2020). Drought conditions have been shown to reduce the diversity and abundance of native bees (Minckley et al. 2013, Hung et al. 2021). Certain aspects of this species' biology may make it more vulnerable to some threats. Andrena perpunctata 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 (N. M. Williams et al., 2010). Although the dietary breadth of Andrena perpunctata is unknown, many species of bees its subgenus (Callandrena) are dietary specialists, 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).

Conservation needs No known conservation actions are in place for this species. Observations of this species are known from national parks and biosphere reserves in Mexico, as well as National Forest Service land in the United States, 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.

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.