Background 
Wild bees are important pollinators that have declined in diversity and abundance during the last decades. Habitat destruction and fragmentation associated with urbanization are reported as part of the main causes of this decline. Urbanization involves dramatic changes of the landscape, increasing the proportion of impervious surface while decreasing that of green areas. Few studies have investigated the effects of urbanization on bee communities. We assessed changes in the abundance, species richness, and composition of wild bee community along an urbanization gradient.


Methodology/Principal Findings 
Over two years and on a monthly basis, bees were sampled with colored pan traps and insect nets at 24 sites located along an urbanization gradient. Landscape structure within three different radii was measured at each study site. We captured 291 wild bee species. The abundance of wild bees was negatively correlated with the proportion of impervious surface, while species richness reached a maximum at an intermediate (50%) proportion of impervious surface. The structure of the community changed along the urbanization gradient with more parasitic species in sites with an intermediate proportion of impervious surface. There were also greater numbers of cavity-nesting species and long-tongued species in sites with intermediate or higher proportion of impervious surface. However, urbanization had no effect on the occurrence of species depending on their social behavior or body size.


Conclusions/Significance 
We found nearly a third of the wild bee fauna known from France in our study sites. Indeed, urban areas supported a diverse bee community, but sites with an intermediate level of urbanization were the most speciose ones, including greater proportion of parasitic species. The presence of a diverse array of bee species even in the most urbanized area makes these pollinators worthy of being a flagship group to raise the awareness of urban citizens about biodiversity.

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Decreasing Abundance, Increasing Diversity and Changing Structure of the Wild Bee Community (Hymenoptera: Anthophila) along an Urbanization Gradient

Agricultural intensification has led to the decrease of the diversity of wild and domestic pollinators For instance, honeybees declined by 59 % in 61 years in the USA About 35 % of major crops in the world depend on pollination services, and 3–8 % of world crop production will disappear without pollinators Indeed, pollination provides several ecosystem services such as enabling crop and honey productions, regulating weeds and other cultural services Agricultural intensification has also decreased weed diversity by about 50 % in 70 years because massive herbicide sprays have reduced the competition between weeds and crops Nevertheless, weeds are at the basis of agricultural foodwebs, providing food to many living organisms In particular, weeds provide flowers for pollinating insects including honey and wild bees Here, we review the decline of weeds and bees We discuss the effect of bees and pollination on crop production We describe the complex interactions between bee pollinators, eg honey and wild bees, and landscape habitats such as crop fields and semi-natural elements For that, we focus on spatial and temporal effects on flower resources We show that weed abundance can reduce crop yields, thus inducing conflict with farmers But weed abundance enhances regulating services by ensuring the survival of honeybees in the absence of oil seed crops Weed abundance also enhances pollination services and, in turn, honey yield for the benefit of beekeepers Weed abundance has also improved the survival of wild flora and the socio-cultural value of landscapes, a major request from the public From those findings, we present a conceptual framework allowing to define ecological engineering options based upon ecosystem services of weeds and pollinators

/pdf/weeds-for-bees-a-review-2vzzd5ojup.pdf

Weeds for bees? A review

Bumble bees represent one of the most important groups of pollinators. In addition to their ecological and economic relevance , they are also a highly charismatic group which can help to increase the interest of people in realizing, enjoying and conserving natural systems. However, like most animals, bum-ble bees are sensitive to climate. In this atlas, maps depicting potential risks of climate change for bumble bees are shown together with informative summary statistics, ecological background information and a picture of each European species. Thanks to the EU FP7 project STEP, the authors gathered over one million bumblebee records from all over Europe. Based on these data, they modelled the current climatic niche for almost all European species (56 species) and projected future climatically suitable conditions using three climate change scenarios for the years 2050 and 2100. While under a moderate change scenario only 3 species are projected to be at the verge of extinction by 2100, 14 species are at high risk under an intermediate change scenario. Under a most severe change scenario as many as 25 species are projected to lose almost all of their climatically suitable area, while a total of 53 species (77% of the 69 European species) would lose the main part of their suitable area. Climatic risks for bumblebees can be extremely high, depending on the future development of human society, and the corresponding effects on the climate. Strong mitigation strategies are needed to preserve this important species group and to ensure the sustainable provision of pollination services, to which they considerably contribute. On the front cover: Bombus hyperboreus, an Arctic bumblebee species that is threatened by global warming

/pdf/climatic-risk-and-distribution-atlas-of-european-bumblebees-1iasom1x7k.pdf

Climatic Risk and Distribution Atlas of European Bumblebees

This study presents DNA barcode records for 4118 specimens representing 561 species of bees belonging to the six families of Apoidea (Andrenidae, Apidae, Colletidae, Halictidae, Megachilidae and Melittidae) found in Central Europe. These records provide fully compliant barcode sequences for 503 of the 571 bee species in the German fauna and partial sequences for 43 more. The barcode results are largely congruent with traditional taxonomy as only five closely allied pairs of species could not be discriminated by barcodes. As well, 90% of the species possessed sufficiently deep sequence divergence to be assigned to a different Barcode Index Number (BIN). In fact, 56 species (11%) were assigned to two or more BINs reflecting the high levels of intraspecific divergence among their component specimens. Fifty other species (9.7%) shared the same Barcode Index Number with one or more species, but most of these species belonged to a distinct barcode cluster within a particular BIN. The barcode data contributed to clarifying the status of nearly half the examined taxonomically problematic species of bees in the German fauna. Based on these results, the role of DNA barcoding as a tool for current and future taxonomic work is discussed.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/1755-0998.12363

DNA barcoding largely supports 250 years of classical taxonomy: identifications for Central European bees (Hymenoptera, Apoidea partim)

Given the predicted expansion of cities throughout the world, understanding the effect of urbanization on bee fauna is a major issue for the conservation of bees. The aim of this study was to understand how urbanization affects wild bee assemblages along a gradient of impervious surfaces and to determine the influence of landscape composition and floral resource availability on these assemblages. We chose 12 sites with a proportion of impervious surfaces (soil covered by parking, roads, and buildings) ranging from 0.06% to 64.31% within a 500 m radius. We collected using pan trapping and estimated the landscape composition of the sites within a 500 m radius and the species richness of plant assemblages within a 200 m radius. We collected 1104 bees from 74 species. The proportion of impervious surfaces at the landscape scale had a negative effect on wild bee abundance and species richness, whereas local flower composition had no effect. Ground-nesting bees were particularly sensitive to the urbanization gradient. This study provides new evidences of the impact of urbanization on bee assemblages and the proportion of impervious surfaces at the landscape scale emerged as a key factor that drives those assemblages.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ece3.2374

The proportion of impervious surfaces at the landscape scale structures wild bee assemblages in a densely populated region

Checklist of the Western Palaearctic Bees (Hymenoptera: Apoidea: Anthophila)

Morocco is a well known hot-spot of biodiversity in the Mediterranean basin. While some taxa like vascular plants are relatively well recorded, important groups of pollinators like bees are still understudied. This article presents an updated checklist of the bee species of Morocco and includes a summary of global and regional distribution of each species. A total of 961 species belonging to six bee families and 68 genera are recorded: Andrenidae (8 genera, 217 species); Apidae (15 genera, 241 species); Colletidae (2 genera, 74 species), Halictidae (12 genera, 144 species), Megachilidae (28 genera, 271 species) and Melittidae (3 genera, 14 species). Among them, 67 species are recorded for the first time in Morocco. Around 70% of the bee fauna of Morocco consists of widespread Palaearctic species. Only 18% of Moroccan species recorded are restricted to North Africa and 8% are Moroccan single-country endemics (81 species). Afrotropical elements in the Moroccan fauna are few, with only 3% of Morocco species co-occuring in that region. This checklist is intended to stimulate new regional research on bees including their taxonomy and biogeography. As many groups of bees have been understudied, discovery of new species for science and new records for the country can be expected. Additional research including inventorying, monitoring, and integrative taxonomic studies are needed to develop a comprehensive strategy for bee conservation in Morocco.

The wild bees (Hymenoptera: Apoidea) of Morocco.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/ecog.05553

Impacts of beekeeping on wild bee diversity and pollination networks in the Aegean Archipelago

Order Hymenoptera, superfamily Apoidea: Families Colletidae, Andrenidae, Halictidae, Melittidae, Megachilidae and Apidae

Following a previously published study on Central Asian species of Sphecodes bees we here present a further report on 20 rarely recorded and little known species. This brings to 34 the number of species of Sphecodes known from this region, with two of them recorded for the first time: Sphecodes scabricollis Wesmael, 1835 and S. hakkariensis Warncke, 1992. Sphecodes sandykachis Astafurova Proshchalykin, sp. n. is described from Turkmenistan and Uzbekistan. Sphecodes atlassa Warncke, 1992, stat. nov. and S. hakkariensis Warncke, 1992, stat. nov. are raised to full species level.

Maximilian Schwarz

Papers

Checklist of the Western Palaearctic Bees (Hymenoptera: Apoidea: Anthophila)

The wild bees (Hymenoptera: Apoidea) of Morocco.

Impacts of beekeeping on wild bee diversity and pollination networks in the Aegean Archipelago

Order Hymenoptera, superfamily Apoidea: Families Colletidae, Andrenidae, Halictidae, Melittidae, Megachilidae and Apidae

New and little known bees of the genus Sphecodes Latreille, 1804 (Hymenoptera: Apoidea: Halictidae) from Central Asia.