The gut microbiome of solitary bees is mainly affected by pathogen assemblage and partially by land use.

Pollinators, including solitary bees, are drastically declining worldwide. Among the factors contributing to this decline, bee pathogens and different land uses are of relevance. The link between the gut microbiome composition and host health has been recently studied for social pollinators (e.g. honeybees), whereas the information related to solitary bees is sparse. This work aimed at the characterization of the gut microbiome of the solitary bees Xylocopa augusti, Eucera fervens and Lasioglossum and attempted to correlate the gut microbial composition with the presence and load of different pathogens and land uses. Solitary bees were sampled in different sites (i.e. a farm, a natural reserve, and an urban plant nursery) showing different land uses. DNA was extracted from the gut, 16S rRNA gene amplified and sequenced. Eight pathogens, known for spillover from managed bees to wild ones, were quantified with qPCR. The results showed that the core microbiome profile of the three solitary bees significantly varied in the different species. Pseudomonas was found as the major core taxa in all solitary bees analyzed, whereas Lactobacillus, Spiroplasma and Sodalis were the second most abundant taxa in X. augusti, E. fervens and Lasioglossum, respectively. The main pathogens detected with qPCR were Nosema ceranae, Nosema bombi and Crithidia bombi, although differently abundant in the different bee species and sampling sites. Most microbial taxa did not show any correlation with the land use, apart from Snodgrassella and Nocardioides, showing higher abundances on less anthropized sites. Conversely, the pathogens species and load strongly affected the gut microbial composition, with Bifidobacterium, Apibacter, Serratia, Snodgrassella and Sodalis abundance that positively or negatively correlated with the detected pathogens load. Therefore, pathogens presence and load appear to be the main factor shaping the gut microbiome of solitary bees in Argentina.

Xicotli Data: a project to retrieve plant-bee interactions from citizen science.

Background: Xicotli data is the short name given to the dataset generated within the project framework "Integration of Biodiversity Data for the Management and Conservation of Wild Bee-Plant Interactions in Mexico (2021-2023)", as xicotli is the generic word for a bee in Nahuatl. The team comprised eco-informaticians, ecologists and taxonomists of both native bees and flora. The generated dataset contains so far 4,532 curated records of the plants, which are potential hosts of species of three focal families of bees native to Mexico: Apidae, Halictidae and Megachilidae and morphological and ecological data of the plant-bee interactions. This dataset was integrated and mobilised from citizen observations available at naturalista.mx (iNat), which were compiled through the iNaturalist project. New information: The new information obtained with the Xicotli data project was: Taxonomic information about bee species curated by taxonomists based on the information contained in iNaturalist;Taxonomic identification of the host plants by a botanist from the photos compiled by the Xicotli Data project;Data on the ecomorphological traits of bees and plants based on expert knowledge and literature. All the data were integrated into the Xicotli Data Project via the creation of new "observation fields". The visibility of the information originally contained in iNaturalist was maximized and can be consulted directly on the iNaturalist platform.

Apoidea of the collections of Lyon, Aix-en-Provence, Marseille and Toulon Museums of Natural History (France).

Background: Many insect species have shown dramatic declines over the last decades, as a result of man-related environmental changes. Many species which were formerly widespread are now rare. To document this trend with evidence, old records of collected specimens are vital. New information: We provide here the data on 9752 bee (Hymenoptera: Apoidea) specimens hosted in several museums of south-east France: Musée des Confluences in Lyon, Muséum d'Histoire Naturelle de Marseille, Muséum d'Aix-en-Provence and the Muséum Départemental du Var in Toulon. Most of the specimens (9256) come from France and include data on 552 named species. For most of these specimens, the geographical location, including geographical coordinates, is based on the locality (town or village) where they were collected. The specimens were captured from the beginning of the nineteenth century to 2018. The identifications of 1377 specimens, mainly belonging to the genus Bombus, are considered reliable, as these were performed or been checked since 2009. All the other reported identifications are the original ones given by the original collectors.

Sensory plasticity in a socially plastic bee.

The social Hymenoptera have contributed much to our understanding of the evolution of sensory systems. Attention has focussed chiefly on how sociality and sensory systems have evolved together. In the Hymenoptera, the antennal sensilla are important for optimizing the perception of olfactory social information. Social species have denser antennal sensilla than solitary species, which is thought to enhance social cohesion through nestmate recognition. In the current study, we test whether sensilla numbers vary between populations of the socially plastic sweat bee Halictus rubicundus from regions that vary in climate and the degree to which sociality is expressed. We found population differences in both olfactory and hygro/thermoreceptive sensilla numbers. We also found evidence that olfactory sensilla density is developmentally plastic: when we transplanted bees from Scotland to the south-east of England, their offspring (which developed in the south) had more olfactory hairs than the transplanted individuals themselves (which developed in Scotland). The transplanted bees displayed a mix of social (a queen plus workers) and solitary nesting, but neither individual nor nest phenotype was related to sensilla density. We suggest that this general, rather than caste-specific sensory plasticity provides a flexible means to optimize sensory perception according to the most pressing demands of the environment. Sensory plasticity may support social plasticity in H. rubicundus but does not appear to be causally related to it.

The Loss of Sociality Is Accompanied by Reduced Neural Investment in Mushroom Body Volume in the Sweat Bee Augochlora Pura (Hymenoptera: Halictidae).

Social behavior has been predicted to select for increased neural investment (the social brain hypothesis) and also to select for decreased neural investment (the distributed cognition hypothesis). Here, we use two related bees, the social Augochlorella aurata (Smith) (Hymenoptera: Halictidae) and the related Augochlora pura (Say), which has lost social behavior, to test the contrasting predictions of these two hypotheses in these taxa. We measured the volumes of the mushroom body (MB) calyces, a brain area shown to be important for cognition in previous studies, as well as the optic lobes and antennal lobes. We compared females at the nest foundress stage when both species are solitary so that brain development would not be influenced by social interactions. We show that the loss of sociality was accompanied by a loss in relative neural investment in the MB calyces. This is consistent with the predictions of the social brain hypothesis. Ovary size did not correlate with MB calyx volume. This is the first study to demonstrate changes in mosaic brain evolution in response to the loss of sociality.

Twenty New Records of Bees (Hymenoptera, Apoidea) for Sardinia (Italy).

In Sardinia, the second largest Mediterranean island, 316 species of bees are known. Here, for the first time, the following 20 taxa are reported: Colletes cunicularius (Linnaeus, 1761), and C. eous Morice, 1904 (Colletidae); Andrena humilis Imhoff, 1832, A. granulosa Pérez, 1902, A. cineraria (Linnaeus, 1758), A. pallitarsis Pérez, 1903, A. rugulosa Stöckhert, 1935, A. savignyi Spinola, 1838, and A. tenuistriata Pérez, 1895 (Andrenidae); Sphecodes reticulatus Thomson, 1870 (Halictidae); Lithurgus tibialis Morawitz, 1875, Chelostoma emarginatum (Nylander, 1856), Dioxys cinctus (Jurine, 1807), Coelioxys caudatus Spinola, 1838, C. obtusus Pérez, 1884, and Megachile ericetorum (Lepeletier, 1841) (Megachilidae); and Nomada melathoracica Imhoff, 1834, N. pulchra Arnold, 1888, Eucera proxima Morawitz, 1875 and Tetralonia malvae (Rossi, 1790) (Apidae). N. pulchra is reported for the first time in Italy.

Cryptic species and hidden ecological interactions of halictine bees along an elevational gradient.

Changes of abiotic and biotic conditions along elevational gradients represent serious challenges to organisms which may promote the turnover of species, traits and biotic interaction partners. Here, we used molecular methods to study cuticular hydrocarbon (CHC) profiles, biotic interactions and phylogenetic relationships of halictid bees of the genus Lasioglossum along a 2,900 m elevational gradient at Mt. Kilimanjaro, Tanzania. We detected a strong species turnover of morphologically indistinguishable taxa with phylogenetically clustered cryptic species at high elevations, changes in CHC profiles, pollen resource diversity, and a turnover in the gut and body surface microbiome of bees. At high elevations, increased proportions of saturated compounds in CHC profiles indicate physiological adaptations to prevent desiccation. More specialized diets with higher proportions of low-quality Asteraceae pollen imply constraints in the availability of food resources. Interactive effects of climatic conditions on gut and surface microbiomes, CHC profiles, and pollen diet suggest complex feedbacks among abiotic conditions, ecological interactions, physiological adaptations, and phylogenetic constraints as drivers of halictid bee communities at Mt. Kilimanjaro.

Cuticular and Dufour's Gland Chemistry Reflect Reproductive and Social State in the Facultatively Eusocial Sweat Bee Megalopta genalis (Hymenoptera: Halictidae).

Queen pheromones evolved independently in multiple eusocial insect lineages, in which they mediate reproductive conflict by inhibiting worker ovarian development. Although fundamentally important for reproductive division of labor - the hallmark of eusociality - their evolutionary origins are enigmatic. Here, we analyze cuticular and Dufour's gland chemistries across alternative social and reproductive phenotypes in Megalopta genalis bees (tribe Augochlorini, family Halictidae) that facultatively express simple eusociality. Reproductive bees have distinct overall glandular and cuticular chemical phenotypes compared with non-reproductive workers. On the cuticle, a likely site of signal transmission, reproductives are enriched for certain alkenes, most linear alkanes, and are heavily enriched for all methyl-branched alkanes. Chemicals belonging to these compound classes are known to function as fertility signals in other eusocial insect taxa. Some macrocyclic lactones, compounds that serve as queen pheromones in the other eusocial halictid tribe (Halictini), are also enriched among reproductives relative to workers. The intra-population facultative eusociality of M. genalis permits direct comparisons between individuals expressing alternative reproductive phenotypes - females that reproduce alone (solitary reproductives) and social queens - to highlight traits in the latter that may be important mediators of eusociality. Compared with solitary reproductives, the cuticular chemistries of queens are more strongly differentiated from those of workers, and furthermore are especially enriched for methyl-branched alkanes. Determining the pheromonal function(s) and information content of the candidate signaling compounds we identify will help illuminate the early evolutionary history of queen pheromones, chemical signals central to the organization of insect eusocial behavior.

A revised genus-level classification for the Neotropical groups of the cleptoparasitic bee tribe Sphecodini Schenck (Hymenoptera, Apidae, Halictinae)

Abstract Sphecodini are a clade of obligatory parasitic Halictinae, comprising 332 species and five genera worldwide. Recently, Sphecodes Latreille was considered polyphyletic according to the results of a molecular phylogeny. Morphological analysis of Neotropical groups revealed groups of species in Sphecodes s.l. that can be recognized at genus level to improve the classification of the tribe. The main objective of this study is to review the generic classification of Sphecodini, with emphasis on Neotropical groups. I propose Austrosphecodes Michener as a separate genus from Sphecodes s.s. and describe a new genus, Melissocleptis gen. nov. for eight known species. Both genera comprise most of the Neotropical species. Nesosphecodes depressus sp. nov. is described for Brazil and a revised diagnosis for Nesosphecodes Engel is given to accommodate this new species and to include data on male terminalia. A revised key for the genera from the Western Hemisphere is provided.

New species of Augochlora (Oxystoglossella) Eickwort (Hymenoptera; Apoidea) from Northeastern Brazil with an identification key for the region.

Within Augochlorini, Augochlora Smith is one of the most speciose genera, with 118 species, and widely distributed groups, occurring from Argentina to Canada. The genus has a remarkable range of social behaviors and nesting substrate preferences. There are two recognized extant subgenera: Augochlora s.s., whose species nest in decaying wood cavities and Oxystoglossella, whose species nest in soil. To date, a single species revision is available for Central Argentina and Uruguay. In the present study we provide a revision of Oxystoglossella species occurring in Northeastern Brazil including the description of three new species: Augochlora bipunctata sp. nov., Augochlora modica sp. nov. and Augochlora tenax sp. nov. Herein Halictus eucnemis Vachal is resurrected from synonymy with Augochlora thalia Smith, and the lectotype of Halictus hemitomes Vachal is presently designated. Augochlora aurinasis is cited for Brazil for the first time. A key to the six species of Oxystoglossella occurring at Northeastern region in Brazil is provided. The three new species are apparently restricted to this region, being one of them probably linked to the Caatinga biome.

Evaluating Native Bee Communities and Nutrition in Managed Grasslands.

Native pollinators are important for providing vital services in agroecosystems; however, their numbers are declining globally. Bees are the most efficient and diverse members of the pollinator community; therefore, it is imperative that management strategies be implemented that positively affect bee community composition and health. Here, we test responses of the bee and flowering plant communities to land management treatments in the context of grasslands in the upper Midwestern United States, a critical area with respect to bee declines. Twelve sites were selected to examine floral resources and wild bee communities based on three different types of grasslands: tallgrass prairie remnants, ungrazed restorations, and grazed restorations. Total bee abundance was significantly higher in ungrazed restorations than remnants, but there were no significant differences among grasslands in community composition or Shannon diversity. Across the three grassland types we also examined mass and lipid stores as nutritional health indicators in three sweat bees (Halictidae), Augochlora pura, Agapostemon virescens, and Halictus ligatus. Although there were no differences in lipid content, total average bee mass was significantly higher in Ag. virescens collected from ungrazed restorations as compared to remnants. Floral abundance of native and non-native species combined was significantly higher in grazed restorations compared to remnants and ungrazed restorations. However, ungrazed restorations had higher abundance and richness of native flowering ramets. These data suggest that bee abundance and nutrition are driven by high abundance of native flowering plant species, rather than total flowering plants.

Macrocyclic Lactones Act as a Queen Pheromone in a Primitively Eusocial Sweat Bee.

Eusociality is characterized by the reproductive division of labor between two castes: fertile queens and largely sterile workers. Queen pheromones are known to influence worker behavior and reproductive physiology and are therefore key components in regulating complex eusocial behavior [1]. Recent studies indicate that cuticular hydrocarbons (CHCs) act as queen pheromones in various eusocial hymenopteran species [2-8]. However, almost all species investigated to date are highly eusocial and do not include extant transitory stages from solitary to eusocial behavior [9]. Indeed, primitively eusocial species, which largely lack morphologically distinct castes, are thought to control worker reproduction through the physical aggression of the queen rather than via pheromones [10-12]. Halictid or sweat bees exhibit a high variability of eusociality including solitary and facultatively eusocial species [9, 13-16]. However, the mechanisms controlling worker reproduction in these transitory species are unknown. The results of a recent correlative study based on caste-specific chemical profiles in various halictid bees of different social levels have revealed an overproduction of macrocyclic lactones in queens compared with workers [17]. Using chemical analyses and behavioral experiments in which we simulated below-ground nests of the primitively eusocial sweat bee Lasioglossum malachurum, we identified a queen pheromone and found that macrocyclic lactones, not CHCs, influence worker behavior and decrease ovarian activation in this species. Our data suggest that the evolution of queen pheromones is more complex than previously inferred from highly eusocial species and shed new light on the complexity of the evolution of queen pheromones.

A revision of the bee genus Augochlora Smith (Hymenoptera; Apoidea) in Southern South America.

Even after more than 250 years of taxonomic research on bees, there are still many gaps in the knowledge about their identity, classification and distribution patterns. Regarding the New World tribe Augochlorini, many efforts have been made in the last years to describe and organize its diversity. Within the tribe, Augochlora Smith has the widest distribution range, as these bees occur from Argentina to Southern Canada, including Caribbean islands. The genus comprises 124 described species in two extant subgenera, and, to date, two partial revisions are available, accounting for central Argentina and Uruguay and for northeastern Brazil. In the present study we review the Augochlora species occurring in Argentina, Paraguay, Uruguay and the southern Brazilian states of Paraná, Rio Grande do Sul, and Santa Catarina. Specimens from other Brazilian states and South American countries were also examined to help with species circumscription. We found 27 species in the studied area, including nine new species (Augochlora atlantica sp. nov., A. australis sp. nov., A. genalis sp. nov., A. helena sp. nov., A. hestia sp. nov., A. hirsuta sp. nov., A. laevicarinata sp. nov., A. mendax sp. nov., and A. scabrata sp. nov.) and the remaining redescribed when necessary. A key for the species occurring in the studied area is provided. Five new synonymies are proposed and the lectotypes of Augochlora francisca and Halictus esox are presently designated. The geographic distribution of most studied species is associated with the Atlantic biome in many ways.

The bee Ruizanthedella mutabilis Spinola (Hymenoptera: Halictidae): a very common but poorly known species studied using integrative taxonomy.

Ruizanthedella mutabilis (Spinola) is a very abundant species in Chile and the northwest of Argentinean Patagonia. In this contribution, Halictus nigrocaeruleus Spinola 1851 is established as a junior synonym of R. mutabilis (Spinola 1851), after considering morphological data, DNA barcoding results, and biological observations. The variability in the colouration of the metasoma has been incorrectly used to distinguish these colour forms as valid species. New records enlarge the distribution of the species in Argentina, from the Andes to the Atlantic coast.

Queen Recognition Signals in Two Primitively Eusocial Halictid Bees: Evolutionary Conservation and Caste-Specific Perception.

Queen signals are known to regulate reproductive harmony within eusocial colonies by influencing worker behavior and ovarian physiology. However, decades of research have resulted in the identification of just a few queen signals, and studies of their mode of action are rare. Our aim was to identify queen recognition signals in the halictid bee Lasioglossum pauxillum and to analyze caste differences in the olfactory perception of queen signals in L. pauxillum and the closely related species L. malachurum. We performed chemical analyses and bioassays to test for caste differences in chemical profiles and worker behavior influenced by queen-specific compounds in L. pauxillum. Our results indicated that caste differences in the chemical profiles were mainly attributable to higher amounts of macrocyclic lactones in queens. Bioassays demonstrated a higher frequency of subordinate behavior in workers elicited by queen-specific amounts of macrocyclic lactones. Thus, macrocyclic lactones function as queen recognition signals in L. pauxillum, as in L. malachurum. Using electrophysiological analyses, we have demonstrated that queens of both tested species lack antennal reactions to certain macrocyclic lactones. Therefore, we assume that this is a mechanism to prevent reproductive self-inhibition in queens. Our results should stimulate debate on the conservation and mode of action of queen signals.

Queen Dominance May Reduce Worker Mushroom Body Size in a Social Bee.

The mushroom body (MB) is an area of the insect brain involved in learning, memory, and sensory integration. Here, we used the sweat bee Megalopta genalis (Halictidae) to test for differences between queens and workers in the volume of the MB calyces. We used confocal microscopy to measure the volume of the whole brain, MB calyces, optic lobes, and antennal lobes of queens and workers. Queens had larger brains, larger MB calyces, and a larger MB calyces:whole brain ratio than workers, suggesting an effect of social dominance in brain development. This could result from social interactions leading to smaller worker MBs, or larger queen MBs. It could also result from other factors, such as differences in age or sensory experience. To test these explanations, we next compared queens and workers to other groups. We compared newly emerged bees, bees reared in isolation for 10 days, bees initiating new observation nests, and bees initiating new natural nests collected from the field to queens and workers. Queens did not differ from these other groups. We suggest that the effects of queen dominance over workers, rather than differences in age, experience, or reproductive status, are responsible for the queen-worker differences we observed. Worker MB development may be affected by queen aggression directly and/or manipulation of larval nutrition, which is provisioned by the queen. We found no consistent differences in the size of antennal lobes or optic lobes associated with differences in age, experience, reproductive status, or social caste.

Pollen metabarcoding reveals broad and species-specific resource use by urban bees.

Bee populations are currently undergoing severe global declines driven by the interactive effects of a number of factors. Ongoing urbanisation has the potential to exacerbate bee declines, unless steps are taken to ensure appropriate floral resources are available. Sown wildflower strips are one way in which floral resources can be provided to urban bees. However, the use of these strips by pollinators in urban environments remains little studied. Here, we employ pollen metabarcoding of the rbcL gene to compare the foraging patterns of different bee species observed using urban sown wildflower strips in July 2016, with a goal of identifying which plant species are most important for bees. We also demonstrate the use of a non-destructive method of pollen collection. Bees were found to forage on a wide variety of plant genera and families, including a diverse range of plants from outside the wildflower plots, suggesting that foragers visiting sown wildflower strips also utilize other urban habitats. Particular plants within the wildflower strips dominated metabarcoding data, particularly Papaver rhoeas and Phacelia tanacetifolia. Overall, we demonstrate that pollinators observed in sown wildflower strips use certain sown foodplants as part of a larger urban matrix.

New species of Neocorynura Schrottky from Brazil (Hymenoptera: Apoidea).

Neocorynura Schrottky is one of the most speciose genera in the Augochlorini with about 80 species. Neocorynura is primarily distributed in the Neotropical region, from Argentina to Mexico. New species have been described recently, but the Brazilian fauna has not been studied at the same rate. Thus, the objective of this study is to provide a revision of Neocorynura species from Brazil. More than 2,500 specimens were studied along with the examination of primary type specimens and/or high resolution photographs of type material. A total of 44 species were recognized, 24 new species are added to the fauna and figured as N. acuta sp.nov., N. aethra sp.nov., N. amabilis sp.nov., N. arethusa sp.nov., N. aurantia sp.nov., N. carmenta sp.nov., N. dictyata sp.nov., N. eliasi sp.nov., N. hebe sp.nov., N. hyalina sp.nov., N. insolita sp.nov., N. laevistriata sp.nov., N. lamellata sp.nov., N. meloi sp.nov., N. nambikwara sp.nov., N nicolle sp.nov., N. olivacea sp.nov., N perfida sp.nov., N. pilosifacies sp.nov., N. proserpina sp.nov., N. rubicunda sp.nov., N. surrufa sp.nov., N. truncata sp.nov., and N. veneta sp.nov. I designate the lectotype for Corynura oiospermi Schrottky and consider this name as a junior synonym of Halictus codion Vachal. Augochloropsis celaeno Schrottky is considered a junior synonym of Corynura pseudobaccha Cockerell. Casosoma semimarginata Cockerell is resurrected from synonymy with Cacosoma aenigma Gribodo. Neocorynura aenigma (Gribodo) and Neocorynura caligans (Vachal) are removed from the faunal list for Brazil. Half of species recognized here are known only for the female. The males of N. atromarginata (Cockerell), N. cuprifrons (Smith), N. dilutipes (Vachal), N. erinnys (Schrottky), N. melamptera (Moure), N. roxane (Schrottky) and N. semimarginata (Cockerell) and females of N. iopodion (Vachal) and N. jucunda (Smith) are described for the first time. Identification keys to females and males are presented.

Floral visitors of canola (Brassica napus L. ) hybrids in Cerrado Mineiro region, Brazil / Visitantes florais em híbridos de canola (Brassica napus L. ) na região do Cerrado Mineiro, Brasil

The objective of this study was to verify floral visitors of canola in the Triângulo Mineiro region, Minas Gerais, Brazil. A completely randomized plot design with two hybrids and 10 replicates was used, totaling 20 plots. The survey of floral visitors was made during 10 days. Faunal analyses of the collected species were performed based on frequency, constancy, dominance, and diversity. A total of 2,676 individuals belonging to 13 species of bees of two families (Apidae and Halictidae) were collected. The diversity index found among hybrids was similar (1.28 in hybrid 61 and 1.50 in hybrid 433). The species Apis mellifera Linnaeus, 1758 (Hymenoptera: Apidae), Paratrigona lineata (Lepeletier, 1836) (Hymenoptera: Apidae), and Trigona spinipes (Fabricius, 1793) (Hymenoptera: Apidae) were the most abundant and constant in the crops during all the evaluated days for both hybrids. So, it is important that efforts be made to conserve natural areas close to crops in order to provide resources for the permanence of floral visitors in the area.(AU)

O objetivo deste estudo foi verificar os visitantes florais de canola na região do Triângulo Mineiro, Minas Gerais, Brasil. ­Utilizou-se um delineamento experimental de blocos inteiramente randomizados com dois híbridos e 10 amostras replicadas, totalizando 20 amostras. A pesquisa de visitantes florais foi feita durante 10 dias. As análises faunísticas das espécies coletadas foram realizadas com base na frequência, constância, domínio, riqueza e diversidade. Um total de 2.676 indivíduos pertencentes a 13 espécies de abelhas de duas famílias (Apidae e Halictidae) foram coletados. A riqueza das espécies encontradas entre os híbridos foi semelhante (10 espécies no híbrido 61 e 12 espécies no híbrido 433), bem como o índice de diversidade (1,28 no híbrido 61 e 1,50 no híbrido 433). A espécie Apis mellifera Linnaeus, 1758 (Hymenoptera: Apidae), Paratrigona lineata (Lepeletier, 1836) (Hymenoptera: Apidae) e Trigona spinipes (Fabricius, 1793) (Hymenoptera: Apidae) foram as mais abundantes e constantes nas culturas durante todos os dias avaliados para ambos os híbridos. Com isso, é importante que sejam feitos esforços para conservar as áreas naturais próximas às culturas, a fim de fornecer recursos para a permanência de visitantes florais na área.(AU)

Social behaviour in bees influences the abundance of Sodalis (Enterobacteriaceae) symbionts.

Social interactions can facilitate transmission of microbes between individuals, reducing variation in gut communities within social groups. Thus, the evolution of social behaviours and symbiont community composition have the potential to be tightly linked. We explored this connection by characterizing the diversity of bacteria associated with both eusocial and solitary bee species within the behaviourally variable family Halictidae using 16S amplicon sequencing. Contrary to expectations, we found few differences in bacterial abundance or variation between social forms; most halictid species appear to share similar gut bacterial communities. However, several strains of Sodalis, a genus described as a symbiont in a variety of insects but yet to be characterized in bees, differ in abundance between eusocial and solitary bees. Phylogenetic reconstructions based on whole-genome alignments indicate that Sodalis has independently colonized halictids at least three times. These strains appear to be mutually exclusive within individual bees, although they are not host-species-specific and no signatures of vertical transmission were observed, suggesting that Sodalis strains compete for access to hosts. The symbiosis between halictids and Sodalis therefore appears to be in its early stages.