John S. Ascher

Delivery of crop pollination services is an insufficient argument for wild pollinator conservation

There is compelling evidence that more diverse ecosystems deliver greater benefits to people, and these ecosystem services have become a key argument for biodiversity conservation. However, it is unclear how much biodiversity is needed to deliver ecosystem services in a cost-effective way. Here we show that, while the contribution of wild bees to crop production is significant, service delivery is restricted to a limited subset of all known bee species. Across crops, years and biogeographical regions, crop-visiting wild bee communities are dominated by a small number of common species, and threatened species are rarely observed on crops. Dominant crop pollinators persist under agricultural expansion and many are easily enhanced by simple conservation measures, suggesting that cost-effective management strategies to promote crop pollination should target a different set of species than management strategies to promote threatened bees. Conserving the biological diversity of bees therefore requires more than just ecosystem-service-based arguments.

The city as a refuge for insect pollinators

Research on urban insect pollinators is changing views on the biological value and ecological importance of cities. The abundance and diversity of native bee species in urban landscapes that are absent in nearby rural lands evidence the biological value and ecological importance of cities and have implications for biodiversity conservation. Lagging behind this revised image of the city are urban conservation programs that historically have invested in education and outreach rather than programs designed to achieve high-priority species conservation results. We synthesized research on urban bee species diversity and abundance to determine how urban conservation could be repositioned to better align with new views on the ecological importance of urban landscapes. Due to insect pollinators relatively small functional requirements-habitat range, life cycle, and nesting behavior-relative to larger mammals, we argue that pollinators put high-priority and high-impact urban conservation within reach. In a rapidly urbanizing world, transforming how environmental managers view the city can improve citizen engagement and contribute to the development of more sustainable urbanization.

Dynamic microbiome evolution in social bees

Honey bees, bumble bees, and stingless bees have related gut microbial communities that are shaped by host evolutionary history. The highly social (eusocial) corbiculate bees, comprising the honey bees, bumble bees, and stingless bees, are ubiquitous insect pollinators that fulfill critical roles in ecosystem services and human agriculture. Here, we conduct wide sampling across the phylogeny of these corbiculate bees and reveal a dynamic evolutionary history behind their microbiota, marked by multiple gains and losses of gut associates, the presence of generalist as well as host-specific strains, and patterns of diversification driven, in part, by host ecology (for example, colony size). Across four continents, we found that different host species have distinct gut communities, largely independent of geography or sympatry. Nonetheless, their microbiota has a shared heritage: The emergence of the eusocial corbiculate bees from solitary ancestors appears to coincide with the acquisition of five core gut bacterial lineages, supporting the hypothesis that host sociality facilitates the development and maintenance of specialized microbiomes.

The effect of repeated, lethal sampling on wild bee abundance and diversity

Summary nBee pollinators provide a critical ecosystem service to wild and agricultural plants but are reported to be declining world-wide due to anthropogenic change. Long-term data on bee abundance and diversity are scarce, and the need for additional quantitative sampling using repeatable methods has been emphasized. Recently, monitoring programmes have begun using a standardized method that employs a combination of pan traps and sweep netting, resulting in lethal sampling of bees. This standardized method can remove a large number of bees from sites during each sampling day, raising concern that the sampling itself could have a negative effect on bee populations. nWe conducted an experiment to assess whether lethal sampling for bees using pan traps and netting affected bee abundance and diversity when done every two weeks throughout a season and over multiple years. We compared bee abundance, richness, evenness and functional group composition between sites that had been sampled every two weeks from 2009 to 2012 to similar sites not previously sampled. nWe found that the standardized method for sampling bees, with specimens from 132 morphospecies, did not affect bee communities in terms of abundance, rarefied richness, evenness, or functional group composition. Thus, our results indicate that the bee communities we sampled are robust to such sampling efforts, despite removing an average of 2862 bees per season. nWe discuss several explanations for why sampling did not affect bee abundance or community structure, including a density-dependent response to reduced competition for resources. nThese results suggest that bee monitoring programmes sampling once every two weeks with pan traps and netting will not affect bee community structure. We urge researchers monitoring bees to utilize standardized protocols so that results can be compared across space and time.

The allometry of bee proboscis length and its uses in ecology

Allometric relationships among morphological traits underlie important patterns in ecology. These relationships are often phylogenetically shared; thus quantifying allometric relationships may allow for estimating difficult-to-measure traits across species. One such trait, proboscis length in bees, is assumed to be important in structuring bee communities and plant-pollinator networks. However, it is difficult to measure and thus rarely included in ecological analyses. We measured intertegular distance (as a measure of body size) and proboscis length (glossa and prementum, both individually and combined) of 786 individual bees of 100 species across 5 of the 7 extant bee families (Hymenoptera: Apoidea: Anthophila). Using linear models and model selection, we determined which parameters provided the best estimate of proboscis length. We then used coefficients to estimate the relationship between intertegular distance and proboscis length, while also considering family. Using allometric equations with an estimation for a scaling coefficient between intertegular distance and proboscis length and coefficients for each family, we explain 91% of the variance in species-level means for bee proboscis length among bee species. However, within species, individual-level intertegular distance was a poor predictor of individual proboscis length. To make our findings easy to use, we created an R package that allows estimation of proboscis length for individual bee species by inputting only family and intertegular distance. The R package also calculates foraging distance and body mass based on previously published equations. Thus by considering both taxonomy and intertegular distance we enable accurate estimation of an ecologically and evolutionarily important trait.

Biodiversity conservation gaps in the Brazilian protected areas

Although Brazil is a megadiverse country and thus a conservation priority, no study has yet quantified conservation gaps in the Brazilian protected areas (PAs) using extensive empirical data. Here, we evaluate the degree of biodiversity protection and knowledge within all the Brazilian PAs through a gap analysis of vertebrate, arthropod and angiosperm occurrences and phylogenetic data. Our results show that the knowledge on biodiversity in most Brazilian PAs remain scant as 71% of PAs have less than 0.01 species records per km2. Almost 55% of Brazilian species and about 40% of evolutionary lineages are not found in PAs, while most species have less than 30% of their geographic distribution within PAs. Moreover, the current PA network fails to protect the majority of endemic species. Most importantly, these results are similar for all taxonomic groups analysed here. The methods and results of our countrywide assessment are suggested to help design further inventories in order to map and secure the key biodiversity of the Brazilian PAs. In addition, our study illustrates the most common biodiversity knowledge shortfalls in the tropics.

Range increase of a Neotropical orchid bee under future scenarios of climate change

Along with other human impacts, climate change is an important driver of biological changes worldwide and is expected to severely affect species distributions. Although dramatic range shifts and contractions are predicted for many taxa occurring at higher latitudes, including bumble bees, the response of widespread tropical species is less clear due in part to scarcity of reliable occurrence data. Newly mobilized specimen records and improved species distribution models facilitate more robust assessment of future climate effects under various scenarios. Here, we predict both current and future distribution of the orchid bee Eulaema nigrita Lepeletier, 1841 (Apidae: Euglossinae), a large-bodied species widely distributed in the Neotropics whose populations within the Amazon region are believed to be controlled by cleptoparasitic Euglossini bees, such as Exaerete smaragdina Guérin-Menéville, 1844 and Aglae caerulea Lepeletier and Serville, 1825. Under both current and future scenarios of climate change, El. nigrita is expected to persist in deforested areas including those that might suffer desertification. While under current climatic conditions this species is not expected to occur in central Amazonia where the forest is still conserved, its range is expected to increase under future scenarios of climate change, especially in areas corresponding to the arc of deforestation in eastern Amazonia. The increase of human-related disturbances in this biome, as well as changes in the relationship of El. nigrita–Ex. smaragdina and El. nigrita–A. caerulea may explain the potential range increase of El. nigrita under future scenarios of climate change.

Effects of fragmentation on a distinctive coastal sage scrub bee fauna revealed through incidental captures by pitfall traps

Abstract Recent reports of pollinator declines have revealed a need to better document how anthropogenic disturbances and biogeography jointly influence wild pollinator communities. Here, we examine the effects of urbanization-induced habitat fragmentation on the native bee fauna inhabiting coastal sage scrub habitats of San Diego County, California, USA, a hotspot of bee biodiversity. Pitfall trapping in natural reserves and scrub habitat fragments yielded 70 native bee species or morphospecies, and revealed that bee species richness was lower in fragments than in reserves. However, fragments and reserves harbored bee assemblages similar in relative abundance, evenness, and community composition. Our samples yielded multiple species that are poorly represented in four of the leading institutions with collections of native bees from the southwestern United States, as well as 16 species represented only by specimen records from outside of San Diego County. Our results highlight the importance of continued efforts to document bee assemblages in under-studied regions with respect to their faunal distribution and basic taxonomy, as well as how they are impacted by anthropogenic disturbances such as habitat fragmentation. We also discuss the value of analyzing vouchered pitfall samples for non-target taxa captured incidentally.

Bees (Hymenoptera: Apoidea: Anthophila) of Gardiners Island, Suffolk County, New York

Abstract n We present a survey of the bee fauna of Gardiners Island, Suffolk County, NY. The study focuses on more than 10,000 bee specimens collected by net during 1976, 1977, and 2005–2011. These surveys recorded 154 bee species and morphospecies in 30 genera. Bee species associated with fields, beaches, and woody plants were well represented in the sample, whereas those requiring herbaceous understory flowers were relatively few. Notable finds include several species with southern affinities that are otherwise scarce in New York State and paratypes of the social parasite Lasioglossum (Dialictus) rozeni. The newly discovered male of Sphecodes johnsonii is diagnosed and imaged. Two Nomada morphospecies may be undescribed. A single worker of the northern species Bombus (Cullumanobombus) rufocinctus provides the first coastal record for New York State. New records of Dianthidium (D.) simile from nearby Long Island and of Pseudoanthidium (P.) nanum from New York City (and nearby New Jersey) increase the number of bee genera and described species recorded from New York State to 45 and 447, respectively. Phenological data may provide new evidence for host-parasite associations. The bee diversity of Gardiners Island is discussed in relation to the bee fauna of the northeastern US, especially records available for other Atlantic coastal islands in the region.

The bees of Michigan (Hymenoptera: Apoidea: Anthophila), with notes on distribution, taxonomy, pollination, and natural history

The state of Michigan occupies an area between the Great Plains and the northeastern United States, bordering four Great Lakes, with diverse biogeographical regions. Michigan also has the second most diverse agriculture in the country, with many crops that depend on bees for pollination. This unique combination provides a wide range of opportunities for bees to persist, yet there is no current published checklist of these important insects. This study was conducted to provide the first annotated checklist of the bee (Apoidea: Anthophila) fauna of Michigan, summarizing aspects of their taxonomy and behavior and to provide provisional conservation assessment. The list was compiled from a critical review of published literature, museum specimens, and database records, supplemented by new collections. In total, 465 species are included in the checklist, including 38 new records, however evidence for 13 species is poor, several more species require taxonomic revision, and the presence of additional species is expected. The exotic megachilid species Megachile apicalis Spinola, M. pusilla Pérez (=concinna Smith, auct.) and Osmia taurus Smith are reported from Michigan for the first time. New state records of native species include Anthidium tenuiflorae Cockerell and Nomada alpha alpha Cockerell, both previously undocumented from eastern North America, and Nomada sphaerogaster Cockerell, which has rarely been recognized. The taxonomy of some bee species is clarified by the formal publication of 11 new synonymies (some previously reported online or in manuscripts). The following list cites junior synonyms first followed by the valid name: Andrena chippewaensis Mitchell 1960 = A. (Simandrena) wheeleri Graenicher 1904; Osmia hendersoni Cockerell 1907 = O. (Melanosmia) tarsata Provancher 1888; Osmia michiganensis Mitchell 1962 = O. (M.) subarctica Cockerell 1912 (new status, removed from synonymy with O. (M.) tersula Cockerell 1912); Sphecodes persimilis Lovell and Cockerell 1907 = S. davisii Robertson 1897; Sphecodes knetschi Cockerell 1898 = S. dichrous Smith 1853; Sphecodes carolinus Mitchell 1956 = S. coronus Mitchell 1956; Sphecodes stygius Robertson 1893 = S. mandibularis Cresson 1872; Sphecodes prostygius Mitchell 1960 = S. fattigi Mitchell 1956; Stelis vernalis Mitchell 1962 = S. coarctatus Crawford 1916; and Stelis michiganensis Mitchell 1962 = S. foederalis Smith 1854. Poorly known Andrena (Cnemidandrena) are discussed, including A. parnassiae Cockerell, a new state record, A. robervalensis Mitchell, and the extralimital A. runcinatae Cockerell. Of these, only A. robervalensis was considered in the subgeneric revision, but we recognize all three as valid species pending further study. Nomada binotata (Robertson 1903) and N. quadrimaculata (Robertson 1903) are removed from synonymy with N. ovata (Robertson 1903), based on examination of the lectotypes. A new species, Triepeolus eliseae Rightmyer, the eastern representative of the verbesinae species group, is described. A putative undescribed species, Osmia aff. trevoris, is documented, but requires additional study for its status to be fully resolved. A rich bee fauna is documented that includes geographically-restricted species, rare and regionally-declining species, and economically-important species, providing information for ongoing conservation planning and future analysis of trends in bee populations.