Search

Life-history traits, which are physical traits or behaviours that affect growth, survivorship and reproduction, could play an important role in how well organisms respond to environmental change. By looking for trait-based responses within groups, we can gain a mechanistic understanding of why environmental change might favour or penalize certain species over others. We monitored the abundance of at least 154 bee species for 8 consecutive years in a subalpine region of the Rocky Mountains to ask whether bees respond differently to changes in abiotic conditions based on their life-history traits. We found that comb-building cavity nesters and larger bodied bees declined in relative abundance with increasing temperatures, while smaller, soil-nesting bees increased. Further, bees with narrower diet breadths increased in relative abundance with decreased rainfall. Finally, reduced snowpack was associated with reduced relative abundance of bees that overwintered as prepupae whereas bees that overwintered as adults increased in relative abundance, suggesting that overwintering conditions might affect body size, lipid content and overwintering survival. Taken together, our results show how climate change may reshape bee pollinator communities, with bees with certain traits increasing in abundance and others declining, potentially leading to novel plant–pollinator interactions and changes in plant reproduction.

Emergence traps have increasingly been used to study ground nesting bees. They offer an advantage over other methods, such as netting or passive traps, because they can directly measure ground nesting bees at a landscape scale. However, emergence trapping for ground nesting bees has limitations, including low catch rates and data that is difficult to interpret. For example, emergence traps catch a combination of actively nesting bees, newly emerging bees from nests provisioned the previous year, overwintering bees, and incidental bees, such as non-ground-nesting species or bees that were simply sleeping on vegetation. Further, a single emergence trap can capture many specimens from a single nest due to the presence of workers, newly emerging reproductives (gynes), or multiple siblings from a nest provisioned the previous year. Due to these factors, a thorough knowledge of the life history of bee species collected is necessary to accurately filter and interpret the data. Here, we provide methods to determine whether bee specimens caught from emergence traps came from nests. Using a combination of trap data, life-history characters, and estimates of bee age, we classify bees as newly emerging, active nests, or incidentally caught. This will allow researchers to reduce the risk of spurious inferences that may over- or under-estimate bee nesting. Many areas of future research remain, particularly studies on the efficacy of emergence traps for ground-nesting bee research as well as a glaring need to better document the life-history of many bee species. Abstract content goes here

Network analyses rarely include fitness components, such as germination, to tie invasive plants to population‐level effects on the natives. We address this limitation in a previously studied network of flower visitors around a suite of native and invasive plants that includes an endemic plant at Badlands National Park, South Dakota, USA. Eriogonum visheri coflowers with two abundant invasive plants, Salsola tragus and Melilotus officinalis, as well as a common congener, E. pauciflorum. Network analyses had suggested strong linkages between E. visheri and S. tragus and E. pauciflorum, with a weaker link to M. officinalis. We measured visitation, pollen deposited on stigmas, achene weight and germination over three field seasons (two for germination) in four populations (two in the final season) of E. visheri and applied in situ pollen treatments to E. visheri, adding pollen from other flowers on the same plant; flowers on other E. visheri plants; S. tragus, M. officinalis, or E. pauciflorum; open pollination; or excluding pollinators. Insect visitation to E. visheri was not affected by floral abundance of any of the focal species. Most visitors were halictid bees; one of these (Lasioglossum packeri) was the only identified species to visit E. visheri all three years. Ninety‐seven percent of pollen on collected E. visheri stigmas was conspecific, but 22% of flowers had >1 grain of E. pauciflorum pollen on stigmas and 7% had >1 grain of S. tragus pollen, Eriogonum visheri (Visher's buckwheat) is a rare endemic plant of management concern in the northern Great Plains. Two invasive species, Melilotus officinalis (yellow sweetclover) and Salsola tragus (Russian thistle) and an abundant congener (E. pauciflorum; fewflower buckwheat) occur and coflower with E. visheri, suggesting that they might interfere with pollination of the rare species. We found no evidence of pollination interference by either of the invasive species. In addition, evidence suggests that the abundant congener may provide an alternative resource to support pollinators that also visit the rarer species.

Reversing biodiversity declines requires a better understanding of organismal mobility, as movement processes dictate the scale at which species interact with the environment. Previous studies have demonstrated that species foraging ranges, and therefore, habitat use increases with body size. Yet, foraging ranges are also affected by other life-history traits, such as sociality, which influence the need of and ability to detect resources. We evaluated the effect of body size and sociality on potential and realized foraging ranges using a compiled dataset of 383 measurements for 81 bee species. Potential ranges were larger than realized ranges and increased more steeply with body size. Highly eusocial species had larger realized foraging ranges than primitively eusocial or solitary taxa. We contend that potential ranges describe species movement capabilities, whereas realized ranges depict how foraging movements result from interactions between species traits and environmental conditions. Furthermore, the complex communication strategies and large colony sizes in highly eusocial species may facilitate foraging over wider areas in response to resource depletion. Our findings should contribute to a greater understanding of landscape ecology and conservation, as traits that influence movement mediate species vulnerability to habitat loss and fragmentation.

In the face of well-documented declines in multiple bumblebee species, it is important to accurately identify species and properly delineate species ranges. Here, we document the range of Bombus auricomus (Robertson) and B. nevadensis Cresson in Minnesota, with particular reference to the unexpected discovery of B. nevadensis in St. Paul. We clarify the relative ranges of these two species and provide additional information on how to reliably identify them in Minnesota using color patterns and morphology, including differences in male genitalia. Our results support the consensus that B. auricomus and B. nevadensis are distinct species. Community science records were integral to fully documenting the range of B. nevadensis in Minnesota. Our findings demonstrate the value of community science data, though it highlights the need for experts to check the data and to be mindful of biases in observations around population centers.

There are four files for this analysis. The Species Data includes information on what bees were collected at which sites. The site by round file contains the site information in a site by round interaction format for recreating the local diversity analysis and contains floral resource richness values for each unique site by round combination. The site data sheet is simply the site information with floral resource richness pooled over the entire sampling season.

Effective monitoring is necessary to provide robust detection of bee declines. In the United States and worldwide, bowl traps have been increasingly used to monitor native bees and purportedly detect declines. However, bowl traps have a suite of flaws that make them poorly equipped to monitor bees. We outline the drawbacks of bowl traps, as well as other passive sampling methods. We emphasize that current methods do not monitor changes in bee abundance. We then propose future approaches to improve bee monitoring efforts, which include improving our understanding of the efficacy and drawbacks of current methods, novel molecular methods, nest censusing, mark-recapture, sampling of focal plant taxa, and detection of range contractions. Overall, we hope to highlight deficiencies of the current state of bee monitoring, with an aim to stimulate research into the efficacy of existing methods and promote novel methods that provide meaningful data that can detect declines without squandering limited resources.

The ability to transport pollen from flowers back to the nest represents a key innovation in the evolution of bees from predatory wasp ancestors. Currently, the origin and evolution of pollen transport remains unsettled. Older hypotheses proposed that crop transport was the original mode of pollen transport, but more recent molecular phylogenies have cast doubt on that view. Instead, more recent hypotheses contend that external transport of dry pollen is ancestral in bees. Here, I propose a new hypothesis to explain the origin and subsequent evolution of pollen transport in bees. I propose that pollen transport arose from adult pollen-feeding behavior and that internal transport of pollen is ancestral in bees. This then led to the evolution of external moist transport, which first required a transition step whereby pollen is temporarily accumulated on the venter on a patch of specialized hairs. Finally, external glazed and dry transport evolved from external moist pollen transport, and the evolution of dry transport led to changes in the location of scopae from the original location on the hind tibia and basitarsus. I illustrate many of these hypothetical evolutionary steps using modern-day bee behavior as an example, with a particular focus on the bee Perdita tortifoliae. Examination of the evolution of pollen transport of pollen wasps (subfamily Masarinae) reveals that they have undergone a parallel evolutionary change. Overall, I lay out a broad hypothetical framework to explain the origin and subsequent evolution of pollen transport in bees. This marks a return to the earlier hypothesis that crop transport is ancestral, and it also represents the first in-depth hypothesis to explain how external transport of moistened pollen could have evolved. The evolutionary history of bees has many implications for the biology of bees in the present day, and I lay out a number of predictions that could help confirm or refute my hypotheses.

The turfgrass lawn is a common feature of urban and suburban communities, often accounting for the largest green spaces by area in these landscapes. Flowering species within turfgrass lawns have the potential to serve as a source of forage for bee pollinators in urban and suburban areas. We intentionally introduced low-growing flowers to turfgrass lawns to promote bee diversity and reduce inputs, while maintaining the traditional aesthetics and recreational uses associated with lawns. We compared bee communities on lawns with naturally-occurring blooms of Trifolium repens to bee communities on florally-enhanced lawns that contained Prunella vulgaris ssp. lanceolata and Thymus serpyllum in addition to T. repens. Trifolium repens provided forage for both wild bee communities and Apis mellifera, with A. mellifera being the most common of the 56 species of bees observed on T. repens. We found that florally-enhanced lawns supported more diverse bee communities than lawns with just T. repens. Furthermore, the bee communities supported by florally-enhanced lawns were significantly different from the bee communities supported by lawns containing just T. repens based on presence-absence data (Jaccard’s dissimilarity index). Our research indicates that A. mellifera colonies and wild bee communities can be supported by allowing T. repens to bloom in turfgrass lawns, and that land managers can support more diverse bee communities by intentionally introducing low-growing species of flowers to lawns.

Twenty-five years ago, Arctomecon humilis, a pollinator-dependent, endangered poppy globally restricted to the extreme northeastern Mojave Desert in southwestern Utah, was pollinated by native bee species and the European honey bee. Follow-up studies beginning in 2012 failed to find the two most important native bee pollinator species, one of which, Perdita meconis, is a strict poppy specialist. We had four objectives: (1) confirm the status of formerly important native bee pollinators; (2) determine the role of the Africanized honey bee which reportedly invaded southern Utah in 2008; (3) examine the effect of the ostensible change in pollinator fauna on fruit set in four populations; (4) describe the pollination proficiency of species that presently visit poppy flowers. For the fourth consecutive survey, P. meconis was absent; its local extinction in Utah now seems certain. Another previously important native pollinator, Eucera quadricincta, was very rare. Also uncommon was the European honey bee, having been largely replaced by Africanized honey bees which have become, in most populations, the prevalent pollinator. Africanized bees forage early in the day and quickly strip flowers of their copious pollen leaving little for native bees. We argue that the invasion of southern Utah by Africanized bees is the most likely cause of the severe disruption of the A. humilis pollination system. The ascension of the Africanized bee is also associated with reduced fruit set in all poppy populations, especially those where plants are sparse. Arctomecon humilis now appears to depend mostly on an invasive species for pollination.

The introduction of exotic species can have profound impacts on mutualisms between native species in invaded areas. However, determining whether a new invader has impacted native species depends on accurately reconstructing the invasion timing. The arrival of Africanized honey bees (AHB) in southern Utah at some point between 1994 and 2011 has recently been implicated in the local extinction of Perdita meconis, a native specialist pollinator of an endangered poppy, Arctomecon humilis. Although AHBs were purportedly first detected in southern Utah in 2008, their presence in nearby Nevada, Arizona, and New Mexico by 1998–2001 suggests that they may have been present in Utah much earlier. We refined the arrival date of AHBs in southern Utah by using a molecular marker to determine maternal ancestry of museum specimens collected between 2000 and 2008. We found that AHBs were present in southern Utah from 2000 onwards, advancing the arrival date of this invader by at least 8 years. This lends credence to the hypothesis that AHBs played a critical role in the local extinction of P. meconis in Utah. This work also highlights the importance of vouchering even common species such as honey bees in museum collections to serve future research needs.

Pollen is the primary protein and nutrient source for bees and they employ many different behaviors to gather it. Numerous terms have been coined to describe pollen gathering behaviors, creating confusion as many are not clearly-defined or overlap with existing terms. There is a need for a clear yet flexible classification that enables accurate, succinct descriptions of pollen gathering behaviors to enable meaningful discussion and comparison. Here, we classify the different pollen gathering behaviors into two main classes: active and incidental pollen collection. Active pollen collection is subdivided into six behaviors: scraping with the extremities, buzzing, rubbing with the body and/or scopae, rubbing with the face, tapping, and rasping. In addition to the active and incidental pollen gathering behaviors, many bees have an intermediate step in which they temporarily accumulate pollen on a discrete patch of specialized hairs. Each behavior is described and illustrated with video examples. Many of these behaviors can be further broken down based on the variations found in different bee species. Different species or individual bees mix and match these pollen collecting behaviors depending on their behavioral plasticity and host plant morphology. Taken together, the different behaviors are combined to create complex behavioral repertoires built on a foundation of simple and basic steps. This classification sets the groundwork for further research on various topics, including behavioral plasticity in different species, comparisons between generalists and specialists, and the relative effectiveness of different pollen gathering behaviors.

Body size is an integral functional trait that underlies pollination-related ecological processes, yet it is often impractical to measure directly. Allometric scaling laws have been used to overcome this problem. However, most existing models rely upon small sample sizes, geographically restricted sampling and have limited applicability for non-bee taxa. Allometric models that consider biogeography, phylogenetic relatedness, and intraspecific variation are urgently required to ensure greater accuracy. We measured body size as dry weight and intertegular distance (ITD) of 391 bee species (4,035 specimens) and 103 hoverfly species (399 specimens) across four biogeographic regions: Australia, Europe, North America, and South America. We updated existing models within a Bayesian mixed-model framework to test the power of ITD to predict interspecific variation in pollinator dry weight in interaction with different co-variates: phylogeny or taxonomy, sexual dimorphism, and biogeographic region. In addition, we used ordinary least squares regression to assess intraspecific dry weight ~ ITD relationships for ten bees and five hoverfly species. Including co-variates led to more robust interspecific body size predictions for both bees and hoverflies relative to models with the ITD alone. In contrast, at the intraspecific level, our results demonstrate that the ITD is an inconsistent predictor of body size for bees and hoverflies. The use of allometric scaling laws to estimate body size is more suitable for interspecific comparative analyses than assessing intraspecific variation. Collectively, these models form the basis of the dynamic R package, “pollimetry,” which provides a comprehensive resource for allometric pollination research worldwide., SCOPUS: ar.j, info:eu-repo/semantics/published

Body size is an integral functional trait that underlies pollination-related ecological processes, yet it is often impractical to measure directly. Allometric scaling laws have been used to overcome this problem. However, most existing models rely upon small sample sizes, geographically restricted sampling and have limited applicability for non-bee taxa. Predictive allometric models that consider biogeography, phylogenetic relatedness and intraspecific variation are urgently required to ensure greater accuracy.Here, we measured body size, as dry weight, and intertegular distance (ITD) of 391 bee species (4035 specimens) and 103 hoverfly species (399 specimens) across four biogeographic regions: Australia, Europe, North America and South America. We updated existing models within a Bayesian mixed-model framework to test the power of ITD to predict interspecific variation in pollinator dry weight in interaction with different co-variates: phylogeny or taxonomy, sexual dimorphism and biogeographic region. In addition, we used ordinary least squares (OLS) regression to assess intraspecific dry weight – ITD relationships for 10 bee and five hoverfly species.Including co-variates led to more robust interspecific body size predictions for both bees (BayesianR2: 0.946; ΔR20.047) and hoverflies (BayesianR2: 0.821; ΔR20.058) relative to models with ITD alone. In contrast, at the intraspecific level, our results demonstrate that ITD is an inconsistent predictor of body size for bees (R2: 0.02 – 0.66) and hoverflies (R2: −0.11 – 0.44).Therefore, predictive allometry is more suitable for interspecific comparative analyses than assessing intraspecific variation. Collectively, these models form the basis of the dynamicRpackage, ‘pollimetry’, which provides a comprehensive resource for allometric research concerning insect pollinators worldwide.

In their recent PNAS article on biparental care in Ceratina nigrolabiata Friese, Mikat et al. (1) demonstrate biparental care and nest guarding by males and present these strategies as previously unknown in bees. However, nest guarding by males has been documented in multiple other bee species, including another species of Ceratina . I am aware of 13 studies that document or suggest nest-guarding behavior in male bees, though I am limited here to the most well-documented examples. The most in-depth descriptions of nest guarding are on macrocephalic males of Lasioglossum erythrurum (Cockerell) by Kukuk and Schwarz … [↵][1]1Email: zportman{at}umn.edu. [1]: #xref-corresp-1-1

International audience; AbstractPurposeful transport of pollen represents a key innovation in the evolution of bees from predatory wasps. Most bees transport pollen on specialized hairs on the hind legs or ventral metasoma in one of three ways: moist, dry, or “glazed,” which combines dry and moist transport. The evolutionary pathway among these three transport modes is unclear, though dry transport has been hypothesized to be ancestral. We address this hypothesis using museum specimens and published records of the bee genera Perdita (Andrenidae) and Hesperapis (Melittidae), two distantly related groups whose pollen transport modes appear to have converged. Most species in both genera transport moistened pollen; glazed and dry transport are limited to derived clades of specialists on floral hosts in Asteraceae and Onagraceae, with specialization on Asteraceae associated with more elaborate scopal hairs. The associations between transport mode, host plant, and hair type may be due to the sticky pollenkitt of asteraceous pollen grains and the viscin threads of Onagraceae pollen, which provide alternates to the binding properties of nectar. These findings suggest that the hypothesis that dry transport is ancestral in bees should be reexamined.

Perdita subgenus Heteroperdita Timberlake, a distinctive subgenus of 22 species from the southwestern United States and adjacent Mexico, all specialists on Tiquilia (Boraginaceae), is revised. Nine new species are described: Perdita ( Heteroperdita ) desdemona Portman, sp. n., P . ( H .) exusta Portman & Griswold, sp. n., P . ( H .) hippolyta Portman & Griswold, sp. n. (male previously incorrectly described as P. pilonotata Timberlake), P . ( H .) hooki Portman & Neff, sp. n., P . ( H .) nuttalliae Portman, sp. n., P . ( H .) prodigiosa Portman & Griswold, sp. n., P . ( H .) sycorax Portman, sp. n., P . ( H .) titania Portman & Griswold, sp. n., and P . ( H .) yanegai Portman, sp. n. The following sexes are associated and described for the first time: the male of P . ( H .) frontalis Timberlake, 1968, the female of P . ( H .) optiva Timberlake, 1954, and the true male of P . ( H .) pilonotata Timberlake, 1980. Perdita ( H .) fasciatella Timberlake, 1980 is proposed as a junior synonym of P . ( H .) sexfasciata Timberlake, 1954. A neotype is designated for P . ( H .) pilonotata Timberlake, 1980. Two species in particular, P. prodigiosa and P. pilonotata , are sexually dimorphic with distinctive ant-like males. Information is presented on floral relationships, phenology, and geographic distribution. Identification keys for males and females are provided.

Perdita subgenus Heteroperdita Timberlake, a distinctive subgenus of 22 species from the southwestern United States and adjacent Mexico, all specialists on Tiquilia (Boraginaceae), is revised. Nine new species are described: Perdita (Heteroperdita) desdemona Portman, sp. n., P. (H.) exusta PortmanGriswold, sp. n., P. (H.) hippolyta PortmanGriswold, sp. n. (male previously incorrectly described as P. pilonotata Timberlake), P. (H.) hooki PortmanNeff, sp. n., P. (H.) nuttalliae Portman, sp. n., P. (H.) prodigiosa PortmanGriswold, sp. n., P. (H.) sycorax Portman, sp. n., P. (H.) titania PortmanGriswold, sp. n., and P. (H.) yanegai Portman, sp. n. The following sexes are associated and described for the first time: the male of P. (H.) frontalis Timberlake, 1968, the female of P. (H.) optiva Timberlake, 1954, and the true male of P. (H.) pilonotata Timberlake, 1980. Perdita (H.) fasciatella Timberlake, 1980 is proposed as a junior synonym of P. (H.) sexfasciata Timberlake, 1954. A neotype is designated for P. (H.) pilonotata Timberlake, 1980. Two species in particular, P. prodigiosa and P. pilonotata, are sexually dimorphic with distinctive ant-like males. Information is presented on floral relationships, phenology, and geographic distribution. Identification keys for males and females are provided.

The monotypic Perdita subgenus Xeromacrotera Timberlake is currently known only from the male sex. Here, the female of Perdita (Xeromacrotera) cephalotes (Cresson, 1878) is associated, resulting in two new junior synonyms of P. (X.) cephalotes: Perdita (Procockerellia) excellens Timberlake, 1958, new synonym and Perdita (Cockerellia) autumnalis Timberlake, 1977, new synonym. The true number of maxillary palpi are reported, and updated subgeneric and species diagnoses are provided. In addition, Perdita boharti PortmanGriswold, new name, is designated as a replacement name for the primary junior homonym P. bohartorum Parker, 1983 (not P. bohartorum Timberlake, 1956) and is assigned to the related subgenus Cockerellia Ashmead.

The monotypic Perdita subgenus Xeromacrotera Timberlake is currently known only from the male sex. Here, the female of Perdita ( Xeromacrotera ) cephalotes (Cresson, 1878) is associated, resulting in two new junior synonyms of P . ( X .) cephalotes : Perdita ( Procockerellia ) excellens Timberlake, 1958, new synonym and Perdita ( Cockerellia ) autumnalis Timberlake, 1977, new synonym. The true number of maxillary palpi are reported, and updated subgeneric and species diagnoses are provided. In addition, Perdita boharti Portman & Griswold, new name, is designated as a replacement name for the primary junior homonym P. bohartorum Parker, 1983 (not P. bohartorum Timberlake, 1956) and is assigned to the related subgenus Cockerellia Ashmead.

Although Megachile Latreille (leafcutter bees) are well known for their diverse nesting habits, records of the genus nesting in live plants are rare. Here, we report the widespread Megachile (Megachile) montivaga Cresson nesting in live thistle (Cirsium neomexicanum Gray), the first explicit record of this behavior in the Nearctic.