Heat and desiccation tolerances predict bee abundance under climate change.

Climate change could pose an urgent threat to pollinators, with critical ecological and economic consequences. However, for most insect pollinator species, we lack the long-term data and mechanistic evidence that are necessary to identify climate-driven declines and predict future trends. Here we document 16 years of abundance patterns for a hyper-diverse bee assemblage1 in a warming and drying region2, link bee declines with experimentally determined heat and desiccation tolerances, and use climate sensitivity models to project bee communities into the future. Aridity strongly predicted bee abundance for 71% of 665 bee populations (species × ecosystem combinations). Bee taxa that best tolerated heat and desiccation increased the most over time. Models forecasted declines for 46% of species and predicted more homogeneous communities dominated by drought-tolerant taxa, even while total bee abundance may remain unchanged. Such community reordering could reduce pollination services, because diverse bee assemblages typically maximize pollination for plant communities3. Larger-bodied bees also dominated under intermediate to high aridity, identifying body size as a valuable trait for understanding how climate-driven shifts in bee communities influence pollination4. We provide evidence that climate change directly threatens bee diversity, indicating that bee conservation efforts should account for the stress of aridity on bee physiology.

Reference genome for the Mojave poppy bee (Perdita meconis), a specialist pollinator of conservation concern.

The Mojave poppy bee, Perdita meconis Griswold (Hymenoptera: Anthophila: Andrenidae), is a species of conservation concern that is restricted to the eastern Mojave Desert of North America. It is a specialist pollinator of two poppy genera, Arctomecon and Argemone (Papaveraceae), and is being considered for listing under the US Endangered Species Act along with one of its pollinator hosts, the Las Vegas bearpoppy (Arctomecon californica). Here, we present a near chromosome-level genome of the Mojave poppy bee to provide a genomic resource that will aid conservation efforts and future research. We isolated DNA from a single, small (<7 mm), male specimen collected using non-ideal preservation methods then performed whole-genome sequencing using PacBio HiFi technology. After quality and contaminant filtering, the final draft genome assembly is 327 Mb, with an N50 length of 17.5 Mb. Annotated repetitive elements compose 37.3% of the genome, although a large proportion (24.87%) of those are unclassified repeats. Additionally, we annotated 18,245 protein-coding genes and 19,433 transcripts. This genome represents one of only a few genomes from the large bee family Andrenidae and one of only a few genomes for pollinator specialists. We highlight both the potential of this genome as a resource for future research, and how high-quality genomes generated from small, non-ideal (in terms of preservation) specimens could facilitate biodiversity genomics.

A globally synthesised and flagged bee occurrence dataset and cleaning workflow.

Species occurrence data are foundational for research, conservation, and science communication, but the limited availability and accessibility of reliable data represents a major obstacle, particularly for insects, which face mounting pressures. We present BeeBDC, a new R package, and a global bee occurrence dataset to address this issue. We combined >18.3 million bee occurrence records from multiple public repositories (GBIF, SCAN, iDigBio, USGS, ALA) and smaller datasets, then standardised, flagged, deduplicated, and cleaned the data using the reproducible BeeBDC R-workflow. Specifically, we harmonised species names (following established global taxonomy), country names, and collection dates and, we added record-level flags for a series of potential quality issues. These data are provided in two formats, "cleaned" and "flagged-but-uncleaned". The BeeBDC package with online documentation provides end users the ability to modify filtering parameters to address their research questions. By publishing reproducible R workflows and globally cleaned datasets, we can increase the accessibility and reliability of downstream analyses. This workflow can be implemented for other taxa to support research and conservation.

Forest restoration treatments indirectly diversify pollination networks via floral- and temperature-mediated effects.

In North American conifer forests, a variety of federally initiated thinning programs are implemented to restore pre-European settlement forest structures, but these changes may impact ecosystem function via impacts on sensitive biotic communities. Across the wildland-urban interface of the Front Range region of Colorado, agencies associated with the Collaborative Forest Landscape Restoration Program (CFLRP) have implemented thinning treatments across thousands of hectares of ponderosa pine forest; here we leverage these treatments as an experimental framework to examine thinning effects on a pollinator community. We measured variation in forest structure and sampled bee community assemblages using multiple methods (trapping and netting) to compare bee biodiversity and patterns of floral visitation by bees (bee-flower networks) between mechanically thinned stands that were 3-10 years after treatment and nonthinned stands. Three key findings emerged: (1) Native bee abundance, richness, and diversity were 120%, 53%, and 37% greater, respectively, in thinned stands. In addition, nestedness, richness, and abundance of bee-flower interactions were all substantially higher in thinned stands, and there was increased functional redundancy in bee assemblages after thinning. (2) Structural equation modeling indicated that variation in temperature and floral abundance were mediated by canopy openness and correlated with bee richness and abundance, thereby indirectly driving variation in bee-flower interactions. (3) Four floral species (Penstemon virens, Cerastium arvense, Erysimum capitatum, and Geranium caespitosum) were identified as key connectors in bee-flower interaction networks, though these were not necessarily the most abundant flowering plants. Our analyses indicate that native bee α-diversity and bee-flower interactions positively responded to thinning treatments, and these effects were indirectly driven by canopy removal. We conclude that CFLRP treatments have conservation value for native bee communities. Further monitoring is warranted to evaluate the longevity of these effects.

Review of the bee genus Pseudoanthidium Friese, 1898 (Hymenoptera: Apoidea: Megachilidae: Anthidiini) of China with descriptions of three new species.

The carder bee genus Pseudoanthidium Friese, 1898, is revised from China. Eight species are confirmed to occur in China, including three new species: Pseudoanthidium (Pseudoanthidium) yanruae Niu Zhu, sp. nov., P. (P.) kunesense Niu Zhu, sp. nov., P. (P.) chenggongense Niu Zhu, sp. nov. There is also one new generic assignment and synonymy: Anthidium kryzhanovskii Wu, 1962 is a junior synonym of P. (P.) orientale (Bingham, 1897). Pseudoanthidium (P.) campulodonta (Wu, 1990) is synonymized with P. (P.) tenellum (Mocsry, 1880). Here we provide descriptions for the three new species and an illustrated key to the known Chinese Pseudoanthidium.

Landscape Effects on Native Bees (Hymenoptera: Anthophila) Captured in Pheromone Traps for Noctuid Crop Pests (Lepidoptera: Noctuidae).

Noctuid pests, including tobacco budworm (Chloridea virescens (Fab.)) and bollworm (Helicoverpa zea (Boddie)), are significant pests of southern row crops including cotton (Gossypium hirsutum L.), corn (Zea mays L.), and soybean (Glycine max (L.) Moench.). This pest complex is seasonally monitored through Hartstack traps that are baited with synthetic lepidopteran pheromones across the southern United States. We examined bycatch from the noctuid traps deployed across the Mississippi Delta in 2015, 2016, and 2017 for the presence of bees. The most abundant species collected were honey bees (Apis mellifera L.), bumble bees (Bombus spp.), and long-horned bees (Melissodes spp.); these three genera accounted for 82.4% of specimens collected. We also evaluated the proportion of local- and landscape-level habitats on the abundance and richness of the bees caught as bycatch. The proportion of natural and semi-natural habitat affected the abundance and richness of bees collected at the landscape level, but not at more local scales. Additional research is needed to better understand these interactions between bycatch and landscape factors to minimize non-target collections.

Partitioned Gene-Tree Analyses and Gene-Based Topology Testing Help Resolve Incongruence in a Phylogenomic Study of Host-Specialist Bees (Apidae: Eucerinae).

Incongruence among phylogenetic results has become a common occurrence in analyses of genome-scale data sets. Incongruence originates from uncertainty in underlying evolutionary processes (e.g., incomplete lineage sorting) and from difficulties in determining the best analytical approaches for each situation. To overcome these difficulties, more studies are needed that identify incongruences and demonstrate practical ways to confidently resolve them. Here, we present results of a phylogenomic study based on the analysis 197 taxa and 2,526 ultraconserved element (UCE) loci. We investigate evolutionary relationships of Eucerinae, a diverse subfamily of apid bees (relatives of honey bees and bumble bees) with >1,200 species. We sampled representatives of all tribes within the group and >80% of genera, including two mysterious South American genera, Chilimalopsis and Teratognatha. Initial analysis of the UCE data revealed two conflicting hypotheses for relationships among tribes. To resolve the incongruence, we tested concatenation and species tree approaches and used a variety of additional strategies including locus filtering, partitioned gene-trees searches, and gene-based topological tests. We show that within-locus partitioning improves gene tree and subsequent species-tree estimation, and that this approach, confidently resolves the incongruence observed in our data set. After exploring our proposed analytical strategy on eucerine bees, we validated its efficacy to resolve hard phylogenetic problems by implementing it on a published UCE data set of Adephaga (Insecta: Coleoptera). Our results provide a robust phylogenetic hypothesis for Eucerinae and demonstrate a practical strategy for resolving incongruence in other phylogenomic data sets.

Bees of the genus Anthidium Fabricius, 1804 (Hymenoptera: Apoidea: Megachilidae: Anthidiini) from China.

The Chinese bees of the genus Anthidium Fabricius, 1804, are reviewed. Twenty-one species are confirmed to occur in China, five of which are described and illustrated as new Chinese endemics: Anthidium (Anthidium) pseudomontanum Niu Zhu, sp. nov., A. (A.) pseudophilorum Niu Zhu, sp. nov., A. (A.) tasitiense Niu Zhu, sp. nov., A. (A.) xuezhongi Niu Zhu, sp. nov., and A. (Proanthidium) qingtaoi Niu Zhu, sp. nov.. The previously unknown female of A. (A.) kashmirense Mavromoustakis, 1937 and male of A. (P.) kashgarense (Cockerell, 1911) are described for the first time. Anthidium (A.) furcatum Wu, 2004 (junior primary homonym, nec Anthidium furcatum Ducke, 1908) is replaced with its valid and available synonym A. (A.) striatum Wu, 2004. New synonymies are also established for A. (A.) kashmirense Mavromoustakis, 1937 = A. (A.) nigroventrale Wu, 1982, syn. nov., and A. (A.) florentinum (Fabricius, 1775) = A. (A.) helianthinum Wu, 2004, syn. nov. The non-Chinese Anthidium amabile Alfken, 1933 (junior primary homonym, nec Anthidium porterae var. amabile Cockerell, 1904) is unavailable and the available name Anthidium (Proanthidium) minimum Pasteels, 1969, is valid for this species. Updated synonymies and distributional data are provided for some widespread Palaearctic species including two now adventive in the New World. For Chinese species, the distribution and floral associations of each are provided along with illustrations and a key to the known species.

Bark beetle outbreak enhances biodiversity and foraging habitat of native bees in alpine landscapes of the southern Rocky Mountains.

Landscape-scale bark beetle outbreaks alter forest structure with direct and indirect effects on plants and animals in forest ecosystems. Using alpine spruce forest and a native bee community as a study system, we tested how tree mortality from bark beetles impacts bee foraging habitats and populations. Bees were collected across the growing season (early-, middle-, and late-season) for two years using passive trapping methods, and collections were used to analyze patterns in species abundances and diversity. Three important findings emerged: (1) forest stands that were post-outbreak had 62% higher floral density and 68% more floral species during peak bloom, respectively, than non-affected stands; (2) bee captures were highest early-season (June) and were not strongly affected by bark beetle outbreak; however, mean number of bee species and Shannon-Weiner diversity were significantly higher in post-outbreak stands and this effect was pronounced early in the growing season. Corresponding analysis of ß-diversity indicated higher accumulation of bee biodiversity in post-outbreak stands and a turnover in the ratio of Bombus: Osmia; (3) bee captures were linked to variation in foraging habitat, but number of bee species and diversity were more strongly predicted by forest structure. Our results provide evidence of increased alpine bee biodiversity in post-outbreak stands and increased availability of floral resources. We conclude that large-scale disturbance from bark beetle outbreaks may drive shifts in pollinator community composition through cascading effects on floral resources, mediated via mortality of overstory trees.

Bee phenology is predicted by climatic variation and functional traits.

Climate change is shifting the environmental cues that determine the phenology of interacting species. Plant-pollinator systems may be susceptible to temporal mismatch if bees and flowering plants differ in their phenological responses to warming temperatures. While the cues that trigger flowering are well-understood, little is known about what determines bee phenology. Using generalised additive models, we analyzed time-series data representing 67 bee species collected over 9 years in the Colorado Rocky Mountains to perform the first community-wide quantification of the drivers of bee phenology. Bee emergence was sensitive to climatic variation, advancing with earlier snowmelt timing, whereas later phenophases were best explained by functional traits including overwintering stage and nest location. Comparison of these findings to a long-term flower study showed that bee phenology is less sensitive than flower phenology to climatic variation, indicating potential for reduced synchrony of flowers and pollinators under climate change.

Bee species checklist of the San Francisco Peaks, Arizona.

BACKGROUND: Here we present a checklist of the bee species found on the C. Hart Merriam elevation gradient along the San Francisco Peaks in northern Arizona. Elevational gradients can serve as natural proxies for climate change, replacing time with space as they span multiple vegetation zones over a short geographic distance. Describing the distribution of bee species along this elevation gradient will help predict how bee communities might respond to changing climate. To address this, we initiated an inventory associated with ecological studies on pollinators that documented bees on the San Francisco Peaks. Sample sites spanned six life zones (vegetation zones) on the San Francisco Peaks from 2009 to 2019. We also include occurrence data from other studies, gathered by querying the Symbiota Collection of Arthropods Network (SCAN) portal covering the San Francisco Peaks region (hereafter referred to as "the Peaks"). NEW INFORMATION: Our checklist reports 359 bee species and morphospecies spanning five families and 46 genera that have been collected in the Peaks region. Prior to our concerted sampling effort there were records for 155 bee species, yet there has not been a complete list of bee species inhabiting the Peaks published to date. Over a 10-year period, we documented an additional 204 bee species inhabiting the Peaks. Our study documents range expansions to northern Arizona for 15 species. The majority of these are range expansions from either southern Arizona, southern Utah, or the Rocky Mountain region of Colorado. Nine species are new records for Arizona, four of which are the southernmost record for that species. An additional 15 species are likely undescribed.

Predicting changes in bee assemblages following state transitions at North American dryland ecotones.

Drylands worldwide are experiencing ecosystem state transitions: the expansion of some ecosystem types at the expense of others. Bees in drylands are particularly abundant and diverse, with potential for large compositional differences and seasonal turnover across ecotones. To better understand how future ecosystem state transitions may influence bees, we compared bee assemblages and their seasonality among sites at the Sevilleta National Wildlife Refuge (NM, USA) that represent three dryland ecosystem types (and two ecotones) of the southwestern U.S. (Plains grassland, Chihuahuan Desert grassland, and Chihuahuan Desert shrubland). Using passive traps, we caught bees during two-week intervals from March-October, 2002-2014. The resulting dataset included 302 bee species and 56 genera. Bee abundance, composition, and diversity differed among ecosystems, indicating that future state transitions could alter bee assemblage composition in our system. We found strong seasonal bee species turnover, suggesting that bee phenological shifts may accompany state transitions. Common species drove the observed trends, and both specialist and generalist bee species were indicators of ecosystem types or months; these species could be sentinels of community-wide responses to future shifts. Our work suggests that predicting the consequences of global change for bee assemblages requires accounting for both within-year and among-ecosystem variation.

Revision of the bee genus Bathanthidium Mavromoustakis (Hymenoptera: Apoidea: Megachilidae: Anthidiini) with description of a new species from China.

This revision of the bee genus Bathanthidium Mavromoustakis, 1953, treats 12 species, with 11 recorded from China, including Bathanthidium fengkaiense Niu Zhu, sp. nov.. Two species are proposed as new combinations in genus Bathanthidium: Anthidium (s. str.) bicolor Wu, 2004, A. (s. str.) monganshanensis Wu, 2004. The two new combinations (B. bicolor, B. monganshanense) are in Bathanthidium (Manthidium), previously considered to include only the type species from Burma and Laos (published records from northeastern India and Malaysia are based on misinterpreted localities). Trachusa (Paraanthidium) concavum (Wu, 1962) and Stelis siamensis Friese, 1925 are synonymized with B. binghami (Friese, 1901). Bathanthidium circinatum Wu, 2004 is transferred to Pseudoanthidium Friese forming the new combination P. (s. str.) circinatum (Wu, 2004). The distribution of each species is given, new distribution sites are marked by asterisk (*) especially. Our results confirm that the genus Bathanthidium has higher species diversity than previously documented and that this diversity is centered in China.

Overview of the bee genus Trachusa Panzer, 1804 (Hymenoptera: Apoidea: Megachilidae: Anthidiini) from China with description of three new species.

The Chinese bees of the genus Trachusa Panzer, 1804 are reviewed. Nine species are confirmed to occur in China. Three new species are described and illustrated: Trachusa (Paraanthidium) pingdaensis Niu, sp. nov., T. (P.) staabi Niu, sp. nov. and T. (P.) wuae Niu, sp. nov. The distribution of each species is given. An illustrated key to the Chinese species is provided.

Checklist of bees (Hymenoptera: Apoidea) from small diversified vegetable farms in south-western Montana.

BACKGROUND: Over three years (2013-2015), we sampled bees using nets and bowl traps on four diversified vegetable farms in Gallatin County, Montana, USA, as part of a study evaluating the use of wildflower strips for supporting wild bees and crop pollination services on farmlands (Delphia et al. In prep). We document 202 species and morphospecies from 32 genera within five families, of which 25 species represent the first published state records for Montana. This study increases our overall understanding of the distribution of wild bee species associated with agroecosystems of the northern US Rockies, which is important for efforts aimed at conserving bee biodiversity and supporting sustainable crop pollination systems on farmlands. NEW INFORMATION: We provide a species list of wild bees associated with diversified farmlands in Montana and increase the number of published bee species records in the state from 374 to at least 399. The list includes new distributional records for 25 wild bee species, including two species that represent considerable expansions of their known ranges, Lasioglossum (Dialictus) clematisellum (Cockerell 1904) with previously published records from New Mexico, Arizona, California and Utah and Melissodes (Eumelissodes) niveus Robertson 1895 which was reported to range from New York to Minnesota and Kansas, south to North Carolina, Alabama and Mississippi.

Decades of native bee biodiversity surveys at Pinnacles National Park highlight the importance of monitoring natural areas over time.

Thousands of species of bees are in global decline, yet research addressing the ecology and status of these wild pollinators lags far behind work being done to address similar impacts on the managed honey bee. This knowledge gap is especially glaring in natural areas, despite knowledge that protected habitats harbor and export diverse bee communities into nearby croplands where their pollination services have been valued at over $3 billion per year. Surrounded by ranches and farmlands, Pinnacles National Park in the Inner South Coast Range of California contains intact Mediterranean chaparral shrubland. This habitat type is among the most valuable for bee biodiversity worldwide, as well as one of the most vulnerable to agricultural conversion, urbanization and climate change. Pinnacles National Park is also one of a very few locations where extensive native bee inventory efforts have been repeated over time. This park thus presents a valuable and rare opportunity to monitor long-term trends and baseline variability of native bees in natural habitats. Fifteen years after a species inventory marked Pinnacles as a biodiversity hotspot for native bees, we resurveyed these native bee communities over two flowering seasons using a systematic, plot-based design. Combining results, we report a total of 450 bee species within this 109km2 natural area of California, including 48 new species records as of 2012 and 95 species not seen since 1999. As far as we are aware, this species richness marks Pinnacles National Park as one of the most densely diverse places known for native bees. We explore patterns of bee diversity across this protected landscape, compare results to other surveyed natural areas, and highlight the need for additional repeated inventories in protected areas over time amid widespread concerns of bee declines.

A list of bees from three locations in the Northern Rockies Ecoregion (NRE) of western Montana.

BACKGROUND: Wild bees that were collected in conjunction with a larger study are presented as a checklist of species for the Northern Rockies Ecoregion of Montana, USA. Over the course of four field seasons (2013-2016), 281 species and morphospecies in 32 genera and five families were collected using insect nets, and identified. This paper addresses the distinct lack of studies monitoring bee species in Montana and contributes to a basic understanding of fauna in the northern Rocky Mountains. NEW INFORMATION: With this study, the number of known bee species in Montana increases by at least six species, from 366 (Kuhlman and Burrows 2017) to 372. Though literature was not reviewed for all the species on this checklist, published records in Montana revealed no listings for Andrena saccata Viereck; Anthidiellum notatum robertsoni (Cockerell); Ashmeadiella meliloti (Cockerell); Ashmeadiella pronitens (Cockerell); Colletes lutzi lutzi Timberlake; and Dioxys productus (Cresson).

Wild bees of Grand Staircase-Escalante National Monument: richness, abundance, and spatio-temporal beta-diversity.

Interest in bees has grown dramatically in recent years in light of several studies that have reported widespread declines in bees and other pollinators. Investigating declines in wild bees can be difficult, however, due to the lack of faunal surveys that provide baseline data of bee richness and diversity. Protected lands such as national monuments and national parks can provide unique opportunities to learn about and monitor bee populations dynamics in a natural setting because the opportunity for large-scale changes to the landscape are reduced compared to unprotected lands. Here we report on a 4-year study of bees in Grand Staircase-Escalante National Monument (GSENM), found in southern Utah, USA. Using opportunistic collecting and a series of standardized plots, we collected bees throughout the six-month flowering season for four consecutive years. In total, 660 bee species are now known from the area, across 55 genera, and including 49 new species. Two genera not previously known to occur in the state of Utah were discovered, as well as 16 new species records for the state. Bees include ground-nesters, cavity- and twig-nesters, cleptoparasites, narrow specialists, generalists, solitary, and social species. The bee fauna reached peak diversity each spring, but also experienced a second peak in diversity in late summer, following monsoonal rains. The majority of GSENM's bees are highly localized, occurring in only a few locations throughout the monument, and often in low abundance, but consistently across the four years. Only a few species are widespread and super-abundant. Certain flowering plants appear to be inordinately attractive to the bees in GSENM, including several invasive species. GSENM protects one of the richest bee faunas in the west; the large elevational gradient, incredible number of flowering plants, and the mosaic of habitats are all likely contributors to this rich assemblage of bees.

Revision of the bee group Anthophora (Micranthophora) (Hymenoptera: Apidae), with notes on potential conservation concerns and a molecular phylogeny of the genus.

Anthophora (Micranthophora) comprises the largest subgenus of Anthophora in the Western Hemisphere, with 26 species. Though previously synonymized with the Anthophora (Heliophila), A. (Micranthophora) is here confirmed as a subgenus, morphological and multi-gene molecular phylogenetic evidence refute this and the synonymy of A. (Micranthophora) to A. (Heliophila) is formally rejected. Characters for (Micranthophora) are given and a key to species is provided. Seven new species are described: Anthophora (Micranthophora) caudata Orr, sp. nov.; Anthophora (Micranthophora) chihuahua Orr, sp. nov.; Anthophora (Micranthophora) escalante Orr, sp. nov.; Anthophora (Micranthophora) parkeri Orr, sp. nov.; Anthophora (Micranthophora) rara Orr, sp. nov.; Anthophora (Micranthophora) striata Orr, sp. nov.; and Anthophora (Micranthophora) timberlakei Orr, sp. nov. Further, four new synonyms are enacted: A. arthuri and A. flexipes to A. albata, A. nigritula to A. exigua, and A. xanthochlora to A. pachyodonta. Distributional and phenological data, as well as known details of nesting biology and floral specialization, are provided. Future research directions and species of potential conservation interest are also discussed.

Taxonomic revision of Cyphanthidium Pasteels (Hymenoptera: Apoidea: Megachilidae: Megachilinae: Anthidiini), an endemic Afrotropical bee genus.

The Afrotropical bee genus Cyphanthidium Pasteels is revised. It comprises four species. Cyphanthidium gessorum, new species, and Cyphanthidium whiteheadi, new species, are described as well as the previously unknown female of Cyphanthidium intermedium. A key for identifying the species is given. Supplemental information is provided on the recently published revisions of Serapista and Plesianthidium.