Molecular phylogeny, historical biogeography and revised classification of andrenine bees (Hymenoptera: Andrenidae)

Extensive loss of forage diversity in social bees owing to flower constancy in simulated environments

Many bees visit just one flower species during a foraging trip, i.e. they show flower constancy. Flower constancy is important for plant reproduction but it could lead to an unbalanced diet, especially in biodiversity-depleted landscapes. It is assumed that flower constancy does not reduce dietary diversity in social bees, such as honeybees or bumblebees, but this has not yet been tested. We used computer simulations to investigate the effects of flower constancy on colony diet in plant species-rich and species-poor landscapes. We also explored if communication about food sources, which is used by many social bees, further reduces forage diversity. Our simulations reveal an extensive loss of forage diversity owing to flower constancy in both species-rich and species-poor environments. Small flower-constant colonies often discovered only 30-50% of all available plant species, thereby increasing the risk of nutritional deficiencies. Communication often interacted with flower constancy to reduce forage diversity further. Finally, we found that food source clustering, but not habitat fragmentation impaired dietary diversity. These findings highlight the nutritional challenges flower-constant bees face in different landscapes and they can aid in the design of measures to increase forage diversity and improve bee nutrition in human-modified landscapes.

A first revision of the Andrena of Iraq (Hymenoptera, Andrenidae), with the description of two new species from Iraqi Kurdistan and additional records from surrounding countries

Iraq is a large country in the Middle East region that borders both Turkey and Iran, countries known to host two of the largest bee faunas globally, as expected for a group of insects that favour dry to Mediterranean climates. Despite this huge regional species richness, the bee fauna of Iraq is chronically understudied and poorly known, both in relative and absolute terms. This is true for the hyper-speciose bee genus Andrena, for which only 17 species have been previously published for Iraq. This work is the first modern contribution to the revision of the Andrena fauna of Iraq. Based on new specimen collections in Duhok Governorate (Iraqi Kurdistan) during 2023, a revised total of 59 Andrena species for Iraq (42 species recorded for the first time) is presented, including the description of two new species: Andrena (Aciandrena) duhokensis Wood, sp. nov. and Andrena (Notandrena) baiocchii Wood, sp. nov. The unknown males of A. (Micrandrena) elam Wood, 2022, A. (Micrandrena) obsidiana Wood, 2022, and A. (Notandrena) ayna Wood, 2023 are described. Andrenabakrajoensis Amin & Mawlood, 2019, syn. nov. is synonymised with A. (Holandrena) variabilis Smith, 1853. Additional records are presented from nearby Middle Eastern countries, particularly Lebanon. These results highlight the fundamentally understudied nature of the Iraqi Andrena fauna.

The mechanism of Andrena camellia in digesting toxic sugars

Camellia oleifera is an economically and medicinally valuable oilseed crop. Honeybee, the most abundant pollinator, rarely visits C. oleifera because of the toxic sugars in the nectar and pollen. These toxic sugars cannot be fully digested by honeybees and inhibit the process of synthesizing trehalose in honeybees. C. oleifera exhibits self-incompatibility, and its pollination heavily depends on Andrena camellia. However, the mechanism by which A. camellia digests toxic sugars in C. oleifera nectar and pollen remains unknown. Consequently, we identified and validated four single-copy genes (α-N-acetyl galactosamine-like, galactokinase, galactose-1-phosphate uridyltransferase, and UDP-galactose-4'-epimerase, abbreviated as NAGA-like, GALK, GALT, and GALE) essential for detoxifying toxic sugars in vitro. Then, we cloned the four genes into Escherichia coli, and expressed enzyme successfully degraded the toxic sugars. The phylogeny suggests that the genes were conserved and functionally diverged among the evolution. These results provide novel insights into pollinator detoxification during co-evolution.

Phylogenomic analysis of Stylops reveals the evolutionary history of a Holarctic Strepsiptera radiation parasitizing wild bees

Holarctic Stylops is the largest genus of the enigmatic insect order Strepsiptera, twisted winged parasites. Members of Stylops are obligate endoparasites of Andrena mining bees and exhibit extreme sexual dimorphism typical of Strepsiptera. So far, molecular studies on Stylops have focused on questions on species delimitation. Here, we utilize the power of whole genome sequencing to infer the phylogeny of this morphologically challenging genus from thousands of loci. We use a species tree method, concatenated maximum likelihood analysis and Bayesian analysis with a relaxed clock model to reconstruct the phylogeny of 46 Stylops species, estimate divergence times, evaluate topological consistency across methods and infer the root position. Furthermore, the biogeographical history and coevolutionary patterns with host species are assessed. All methods recovered a well resolved topology with close to all nodes maximally supported and only a handful of minor topological variations. Based on the result, we find that included species can be divided into 12 species groups, seven of them including only Palaearctic species, three Nearctic and two were geographically mixed. We find a strongly supported root position between a clade formed by the spreta, thwaitesi and gwynanae species groups and the remaining species and that the sister group of Stylops is Eurystylops or Eurystylops + Kinzelbachus. Our results indicate that Stylops originated in the Western Palaearctic or Western Palaearctic and Nearctic in the early Neogene or late Paleogene, with four independent dispersal events to the Nearctic. Cophylogenetic analyses indicate that the diversification of Stylops has been shaped by both significant coevolution with the mining bee hosts and host-shifting. The well resolved and strongly supported phylogeny will provide a valuable phylogenetic basis for further studies into the fascinating world of Strepsipterans.

Integrated phylogenomic approaches in insect systematics

The increased accessibility of genomic and imaging methods, and the improved access to ecological, spatial, and other natural history-related data is allowing for insect systematics to grow and find answers to central evolutionary and taxonomic questions. Today, integrated studies in insect phylogenomics and systematics are combining natural history, behavior, developmental biology, morphology, fossils, geographic range data, and ecological interactions. This integration is contributing to the clarification of evolutionary relationships, and the recognition of the role played by these factors on the evolution of insects. Future work should continue to build on these advances, seeking to further increase open-access databasing and support for natural history research, as well as expand its analytical palettes.

A supermatrix phylogeny of the world's bees (Hymenoptera: Anthophila)

The increasing availability of large molecular phylogenies has provided new opportunities to study the evolution of species traits, their origins and diversification, and biogeography; yet there are limited attempts to synthesise existing phylogenetic information for major insect groups. Bees (Hymenoptera: Anthophila) are a large group of insect pollinators that have a worldwide distribution, and a wide variation in ecology, morphology, and life-history traits, including sociality. For these reasons, as well as their major economic importance as pollinators, numerous molecular phylogenetic studies of family and genus-level relationships have been published, providing an opportunity to assemble a bee 'tree-of-life'. We used publicly available genetic sequence data, including phylogenomic data, reconciled to a taxonomic database, to produce a concatenated supermatrix phylogeny for the Anthophila comprising 4,586 bee species, representing 23% of species and 82% of genera. At family, subfamily, and tribe levels, support for expected relationships was robust, but between and within some genera relationships remain uncertain. Within families, sampling of genera ranged from 67 to 100% but species coverage was lower (17-41%). Our phylogeny mostly reproduces the relationships found in recent phylogenomic studies with a few exceptions. We provide a summary of these differences and the current state of molecular data available and its gaps. We discuss the advantages and limitations of this bee supermatrix phylogeny (available online at beetreeoflife.org), which may enable new insights into long standing questions about evolutionary drivers in bees, and potentially insects more generally.

Global taxonomic, functional, and phylogenetic diversity of bees in apple orchards

An essential prerequisite to safeguard pollinator species is characterisation of the multifaceted diversity of crop pollinators and identification of the drivers of pollinator community changes across biogeographical gradients. The extent to which intensive agriculture is associated with the homogenisation of biological communities at large spatial scales remains poorly understood. In this study, we investigated diversity drivers for 644 bee species/morphospecies in 177 commercial apple orchards across 33 countries and four global biogeographical biomes. Our findings reveal significant taxonomic dissimilarity among biogeographical zones. Interestingly, despite this dissimilarity, species from different zones share similar higher-level phylogenetic groups and similar ecological and behavioural traits (i.e. functional traits), likely due to habitat filtering caused by perennial monoculture systems managed intensively for crop production. Honey bee species dominated orchard communities, while other managed/manageable and wild species were collected in lower numbers. Moreover, the presence of herbaceous, uncultivated open areas and organic management practices were associated with increased wild bee diversity. Overall, our study sheds light on the importance of large-scale analyses contributing to the emerging fields of functional and phylogenetic diversity, which can be related to ecosystem function to promote biodiversity as a key asset in agroecosystems in the face of global change pressures.

Phylogeny of Rhynchium and Its Related Genera (Hymenoptera: Eumeninae) Based on Universal Single-Copy Orthologs and Ultraconserved Elements

The subfamily Eumeninae is a large group of fierce predatory insects that prey mainly on the larvae of Lepidoptera pests. Because of the highly similar morphologies of the genus Rhynchium and its related genera in the subfamily, including Rhynchium Spinola, Allorhynchium van der Vecht, Anterhynchium de Saussure, Pararrhynchium de Saussure, it is essential to delineate their relationships. A previous phylogenetic analysis based on mitochondrial genomes suggested the inconsistent relationships of these genera under traditional classification based on morphological characters. In this study, we first used single-copy orthologs [USCO] and ultraconserved elements [UCE] extracted from 10 newly sequenced low-coverage whole genomes to resolve the phylogenetic relationships of the above genera. The newly sequenced genomes are 152.99 Mb to 211.49 Mb in size with high completeness (BUSCO complete: 91.5-95.6%) and G + C content (36.31-38.76%). Based on extracted 5811 USCOs and 2312 UCEs, the phylogenetic relationships of Rhynchium and its related genera were: ((Allorhynchium + Lissodynerus) + (Pararrhynchium + (Anterhynchium + (Dirhynchium + Rhynchium)))), which was consistent with the mitochondrial genome results. The results supported the genus Rhynchium as monophyletic, whereas Anterhynchium was recovered as paraphyletic, with Anterhynchium (Dirhynchium) as a sister to Rhynchium and hence deserving generic status; In addition, in the genus Pararrhynchium, P. septemfasciatus feanus and P. venkataramani were separated, not clustered on a branch, just as P. septemfasciatus feanus was not together with P. striatum based on mitochondrial genomes. Since Lissodynerus septemfasciatus, the type species of the genus Lissodynerus, was transferred to Pararrhynchium, it is considered that the genus Lissodynerus should be restituted as a valid genus, not a synonym of Pararrhynchium.

The evolutionary history of bees in time and space

Bees are the most significant pollinators of flowering plants. This partnership began ca. 120 million years ago, but the uncertainty of how and when bees spread across the planet has greatly obscured investigations of this key mutualism. We present a novel analysis of bee biogeography using extensive new genomic and fossil data to demonstrate that bees originated in Western Gondwana (Africa and South America). Bees likely originated in the Early Cretaceous, shortly before the breakup of Western Gondwana, and the early evolution of any major bee lineage is associated with either the South American or African land masses. Subsequently, bees colonized northern continents via a complex history of vicariance and dispersal. The notable early absences from large landmasses, particularly in Australia and India, have important implications for understanding the assembly of local floras and diverse modes of pollination. How bees spread around the world from their hypothesized Southern Hemisphere origin parallels the histories of numerous flowering plant clades, providing an essential step to studying the evolution of angiosperm pollination syndromes in space and time.

The new annotated checklist of the wild bees of Europe (Hymenoptera: Anthophila)

At a time when nature conservation has become essential to ensure the long-term sustainability of our environment, it is widely acknowledged that conservation actions must be implemented within a solid taxonomic framework. In preparation for the upcoming update of the IUCN Red List, we here update the European checklist of the wild bees (sensu the IUCN geographical framework). The original checklist, published in 2014, was revised for the first time in 2017. In the present revision, we add one genus, four subgenera and 67 species recently described, 40 species newly recorded since the latest revision (including two species that are not native to Europe), 26 species overlooked in the previous European checklists and 63 published synonymies. We provide original records for eight species previously unknown to the continent and, as original taxonomic acts, we provide three new synonyms, we consider two names as nomina nuda, ten names as nomina dubia, three as species inquirenda, synonymize three species and exclude 40 species from the previous checklist. Around a hundred other taxonomic changes and clarifications are also included and discussed. The present work revises the total number of genera for IUCN Europe to 77 and the total number of species to 2,138. In addition to specifying the taxonomic changes necessary to update the forthcoming Red List of European bees, we discuss the sampling and taxonomic biases that characterise research on the European bee fauna and highlight the growing importance of range expansions and species invasions.

A checklist of the bees (Hymenoptera: Apoidea) of Minnesota

Research studies and conservation actions aimed at improving conditions for bees require a basic understanding of which species are present in a given region. The US state of Minnesota occupies a unique geographic position at the confluence of eastern deciduous forests, northern boreal forests, and western tallgrass prairie, which has led to a diverse and unique bee fauna. In recent years there have been multiple ongoing bee-focused inventory and research projects in Minnesota. Combined with the historic specimens housed in the University of Minnesota Insect Collection and other regional collections, these furnished a wealth of specimens available to form the basis of a statewide checklist. Here, we present the first comprehensive checklist of Minnesota bee species, documenting a total of 508 species in 45 genera. County-level occurrence data is included for each species, and further information on distribution and rarity is included for species of regional or national interest. Some species have their taxonomy clarified, with Perdita citrinella Graenicher, 1910 syn. nov. recognized as a junior synonym of Perdita perpallida Cockerell, 1901, P. bequaerti syn. nov. recognized as a junior synonym of P. pallidipennis Graenicher, 1910 stat. nov., Anthidiellum boreale (Robertson, 1902) stat. nov. recognized as a full species, and Anthidiellium beijingense Portman & Ascher nom. nov. is proposed for A. boreale Wu to resolve the homonymy with A. boreale (Robertson). We further include a list of species that may occur in Minnesota and highlight 11 species occurring in the state that are considered non-native. Recent collecting efforts, as well as increased taxonomic attention paid to Minnesota bees, have resulted in 66 species that have only been documented in the last 10 years. As a first step in determining native bees of conservation concern, we document 38 species that have not been detected in the state during the last 50 years and discuss their conservation status, along with other species for which evidence of decline exists. The checklist of Minnesota bees will continue to grow and change with additional surveys and research studies. In particular, recent surveys have continued to detect new bee species, and many bee groups are in need of taxonomic revision, with the most recent revisions for many genera occurring decades ago. Overall, this checklist strengthens our understanding of the bees of Minnesota and the broader region, informs conservation assessments, and establishes a baseline for faunal change.

The type specimens of bees (Hymenoptera: Apoidea) deposited in the Zoological Institute of the Russian Academy of Sciences, St. Petersburg. Contribution VI. Family Andrenidae, genus Andrena Fabricius, 1775, taxa described by V. Popov

The type specimens for names of bee taxa in the genus Andrena Fabricius, 1775, described by V.B. Popov and which are deposited in the Zoological Institute, Russian Academy of Sciences (St. Petersburg) are reviewed. Primary types of 19 taxa are illustrated and detailed information is provided. New synonymies are established for Andrena chengtehensis Yasumatsu, 1935 (= A. nova Popov, 1940, syn. nov.) and A. skorikovi Popov, 1940 (=A. firuzaensis Popov, 1940, syn. nov.; =A. firuzaensis popovella Gusenleitner & Schwarz, 2002, syn. nov.; = Andrena iranella Popov, 1940, syn. nov.). Based on study of the the lectotype, we consider Andrena discophora transhissarica Popov, 1958, stat. rev., at the subspecific level, and not as a distinct species, as opposed to Shebl & Tadauchi (2011). Lectotypes are here designated for the following twelve nominal taxa: Andrena alashanica Popov, 1949, A. discophora transhissarica Popov, 1958, A. eoa Popov, 1949, A. fedtschenkoi djumensis Popov, 1947, A. firuzaensis Popov, 1940, A. iranella Popov, 1940, A. lebedevi Popov, 1940, A. nanshanica Popov, 1940, A. nova Popov, 1940, A. shakuensis Popov, 1949, A. subconsobrina Popov, 1949, and A. tadzhica Popov, 1949.

Sociality is a key driver of foraging ranges in bees

Bees are important pollinators of wild and agricultural plants^1,2,3,4,5 and there is increasing evidence that many bee populations decline due to a combination of habitat loss, climate change, pesticides, and other anthropogenic effects.^{6,7,8,9,10,11} One trait that shapes both their role in plant reproduction^12,13 and their exposure to anthropogenic stressors is the distance at which bees forage. It has been suggested that bee sociality¹⁴ and diet¹⁵ affect bee foraging ranges, but how these traits and their potential interactions drive foraging ranges remains unclear. We analyzed flight distance data from 90 bee species and developed an agent-based model to test how social, dietary, and environmental factors affect foraging ranges. We confirm that bee sociality is positively associated with foraging range, with average-sized social bees foraging up to 3 times farther from the nest than size-matched solitary bees. A comparative analysis of social bees and computer simulations shows that foraging distances increase with colony size, supporting the hypothesis that greater foraging distances are an emergent property of increasing colony sizes in a food-limited environment. Flower constancy and communication, two traits often found in social bees, synergistically increase foraging distances further in many simulated environments. Diet breadth (oligolectic versus polylectic diet), on the other hand, does not appear to affect foraging ranges in solitary bees. Our findings suggest that multiple traits linked to bee sociality explain why social bees have greater foraging ranges. This has implications for predicting pollination services and for developing effective conservation strategies for bees and isolated plant populations.^{15,16,17,18,19}.

Testing the systematic status of Homalictus and Rostrohalictus with weakened cross-vein groups within Halictini (Hymenoptera: Halictidae) using low-coverage whole-genome sequencing

The halictid genus Lasioglossum, as one of the most species-rich bee groups with persistently contentious subgeneric boundaries, is one of the most challenging bee groups from a systematic standpoint. An enduring question is the relationship of Lasioglossum and Homalictus, whether all halictine bees with weakened distal wing venation comprise one or multiple genera. Here, we analyzed the phylogenetic relationships among the subgroups within Lasioglossum s.l. based on thousands of single-copy orthologs and ultraconserved elements, which were extracted from 23 newly sequenced low-coverage whole genomes alongside a published genome (22 ingroups plus 2 outgroups). Both marker sets provided consistent results across maximum likelihood and coalescent-based species tree approaches. The phylogenetic and topology test results show that the Lasioglossum and Hemihalictus series are reciprocally monophyletic and Homalictus and Rostrohalictus are valid subgenera of Lasioglossum. Consequently, we lower Homalictus to subgenus status within Lasioglossum again, and we also raise Rostrohalictus to subgenus status from its prior synonymy with subgenus Hemihalictus. Lasioglossum przewalskyi is also transferred to the subgenus Hemihalictus. Ultimately, we redefine Lasioglossum to include all halictine bees with weakened distal wing venation.

The bees of the genus Andrena Fabricius, 1775 (Hymenoptera, Andrenidae) described by Ferdinand Morawitz from the collection of Aleksey Fedtschenko

The type specimens of the genus Andrena Fabricius, 1775, described by Ferdinand Morawitz from the collection of Aleksey Fedtschenko deposited in the Zoological Museum of the Moscow State University and in the Zoological Institute, Russian Academy of Sciences, St. Petersburg (Russia), are critically reviewed. Precise information with illustrations of types for 52 taxa is provided; of these 39 species are valid and thirteen are invalid (ten synonyms and three homonyms). Lectotypes are here designated for the following 24 nominal taxa: Andrenaacutilabris Morawitz, 1876, A.aulica Morawitz, 1876, A.bicarinata Morawitz, 1876, A.combusta Morawitz, 1876, A.comparata Morawitz, 1876, A.corallina Morawitz, 1876, A.discophora Morawitz, 1876, A.fedtschenkoi Morawitz, 1876, A.initialis Morawitz, 1876, A.laeviventris Morawitz, 1876, A.leucorhina Morawitz, 1876, A.mucorea Morawitz, 1876, A.nitidicollis Morawitz, 1876, A.oralis Morawitz, 1876, A.planirostris Morawitz, 1876, A.ravicollis Morawitz, 1876, A.rufilabris Morawitz, 1876, A.sarta Morawitz, 1876, A.smaragdina Morawitz, 1876, A.sogdiana Morawitz, 1876, A.subaenescens Morawitz, 1876, A.tuberculiventris Morawitz, 1876, A.turkestanica Morawitz, 1876, and A.virescens Morawitz, 1876.

Evolution of andrenine bees reveals a long and complex history of faunal interchanges through the Americas during the Mesozoic and Cenozoic

Bees are presumed to have arisen in the early to mid-Cretaceous coincident with the fragmentation of the southern continents and concurrently with the early diversification of the flowering plants. Here, we apply DNA sequences from multiple genes to recover a dated phylogeny and historical biogeographic of andrenine bees, a large group of 3000 species mainly distributed in arid areas of North America, South America, and the Palearctic region. Our results corroborate the monophyly of Andreninae and points toward a South America origin for the group during the Late Cretaceous. Overall, we provide strong evidence of amphitropical distributional pattern currently observed in the American continent as result of faunal interchange in at least three historical periods, much prior to the Panama Isthmus closure. The Palearctic diversity is shown to have arisen from North America during the Eocene and Miocene, and the Afrotropical lineages likely originated from the Palearctic region in the Miocene when the Sahara Desert was mostly vegetated. The incursions from South to North America and then onto the Old World are chronological congruent with periods when open-vegetation habitats were available for trans-continental dispersal and at the times when aridification and temperature decline offered favorable circumstances for bee diversification.

Morphological and genetic data suggest a complex pattern of inter-island colonisation and differentiation for mining bees (Hymenoptera: Anthophila: Andrena) on the Macaronesian Islands

Oceanic islands have long been considered engines of differentiation and speciation for terrestrial organisms. Here we investigated colonisation and radiation processes in the Madeira Archipelago and the Canary Islands of the Andrena wollastoni group of bees (subgenus Micrandrena), which comprises six endemic species and five endemic subspecies on the islands. Mitochondrial COI sequences support the monophyly of the four species of the Canary Islands and the two species of the Madeira Archipelago and suggest a relatively young age for all taxa. The data do not support a simple stepping-stone model (eastern-western colonisation from the mainland, with splitting into new taxa), but suggest Andrena gomerensis (extant on La Gomera and La Palma) or its ancestor as the basal lineage from which all other taxa evolved. Andrena lineolata (Tene-rife) or its putative ancestor (A. gomerensis) is sister to A. dourada (Porto Santo), A. catula (Gran Canaria), and A. acuta (also Tenerife). Andrena dourada (Porto Santo) and A. wollastoni (Madeira Island) are sister species. Morphologically and morphometrically defined subspecies were not distinguishable with COI DNA sequences. Colonisation likely led from the Canary Islands to the Madeira Archipelago and not from the mainland directly to the latter.