Honey bees infer source location from the dances of returning foragers.

Honeybees (Apis mellifera carnica) communicate the direction and distance to a food source by means of a waggle dance. We ask whether bees recruited by the dance use it only as a flying instruction, with the technical form of a polar vector, or also translate it into a location vector that enables them to set courses directed toward the food source from arbitrary locations within their familiar territory. The flights of recruits captured on exiting the hive and released at distant sites were tracked by radar. The recruits performed first a straight flight in approximately the compass direction indicated by the dance. However, this "vector" portion of their flights and the ensuing tortuous "search" portion were strongly and differentially affected by the release site. Searches were biased toward the true location of the food and away from the location specified by translating the origin for the danced polar vector to the release site. We conclude that by following the dance recruits get two messages, a polar flying instruction (bearing and range from the hive) and a location vector that enables them to approach the source from anywhere in their familiar territory. The dance communication is much richer than thought so far.

Mechanisms of Pathogen and Pesticide Resistance in Honey Bees.

Bees are the most important insect pollinators of the crops humans grow, and Apis mellifera, the Western honey bee, is the most commonly managed species for this purpose. In addition to providing agricultural services, the complex biology of honey bees has been the subject of scientific study since the 18th century, and the intricate behaviors of honey bees and ants, fellow hymenopterans, inspired much sociobiological inquest. Unfortunately, honey bees are constantly exposed to parasites, pathogens, and xenobiotics, all of which pose threats to their health. Despite our curiosity about and dependence on honey bees, defining the molecular mechanisms underlying their interactions with biotic and abiotic stressors has been challenging. The very aspects of their physiology and behavior that make them so important to agriculture also make them challenging to study, relative to canonical model organisms. However, because we rely on A. mellifera so much for pollination, we must continue our efforts to understand what ails them. Here, we review major advancements in our knowledge of honey bee physiology, focusing on immunity and detoxification, and highlight some challenges that remain.

Behavioral genetics and genomics: Mendel's peas, mice, and bees.

The question of the heritability of behavior has been of long fascination to scientists and the broader public. It is now widely accepted that most behavioral variation has a genetic component, although the degree of genetic influence differs widely across behaviors. Starting with Mendel's remarkable discovery of "inheritance factors," it has become increasingly clear that specific genetic variants that influence behavior can be identified. This goal is not without its challenges: Unlike pea morphology, most natural behavioral variation has a complex genetic architecture. However, we can now apply powerful genome-wide approaches to connect variation in DNA to variation in behavior as well as analyses of behaviorally related variation in brain gene expression, which together have provided insights into both the genetic mechanisms underlying behavior and the dynamic relationship between genes and behavior, respectively, in a wide range of species and for a diversity of behaviors. Here, we focus on two systems to illustrate both of these approaches: the genetic basis of burrowing in deer mice and transcriptomic analyses of division of labor in honey bees. Finally, we discuss the troubled relationship between the field of behavioral genetics and eugenics, which reminds us that we must be cautious about how we discuss and contextualize the connections between genes and behavior, especially in humans.

An insect brain organizes numbers on a left-to-right mental number line.

The "mental number line" (MNL) is a form of spatial numeric representation that associates small and large numbers with the left and right spaces, respectively. This spatio-numeric organization can be found in adult humans and has been related to cultural factors such as writing and reading habits. Yet, both human newborns and birds order numbers consistently with an MNL, thus raising the question of whether culture is a main explanation for MNL. Here, we explored the numeric sense of honey bees and show that after being trained to associate numbers with a sucrose reward, they order numbers not previously experienced from left to right according to their magnitude. Importantly, the location of a number on that scale varies with the reference number previously trained and does not depend on low-level cues present on numeric stimuli. We provide a series of neural explanations for this effect based on the extensive knowledge accumulated on the neural underpinnings of visual processing in honey bees and conclude that the MNL is a form of numeric representation that is evolutionarily conserved across nervous systems endowed with a sense of number, irrespective of their neural complexity.

Ecology and Management of African Honey Bees (Apis mellifera L.).

In Africa, humans evolved as honey hunters of honey bee subspecies adapted to diverse geographical regions. Beekeeping today is practiced much as it was when Africans moved from honey hunting to beekeeping nearly 5,000 years ago, with beekeepers relying on seasonally available wild bees. Research suggests that populations are resilient, able to resist diseases and novel parasites. Distinct biomes, as well as environmental pressures, shaped the behavior and biology of these bees and in turn influenced how indigenous beekeeping developed. It appears that passive beekeeping practices that enabled free-living populations contributed to the overall resilience and health of the bee. There is clearly a need for research aimed at a deeper understanding of bee biology and the ecosystems from which they benefit and on which humans depend, as well as a growing realization that the management of these bees requires an indigenous approach that reflects a broader knowledge base and the economics of local communities and markets.

Varroa destructor parasitism and Deformed wing virus infection in honey bees are linked to peroxisome-induced pathways.

The ectoparasitic mite Varroa destructor transmits and triggers viral infections that have deleterious effects on honey bee colonies worldwide. We performed a manipulative experiment in which worker bees collected at emergence were exposed to Varroa for 72 h, and their proteomes were compared with those of untreated control bees. Label-free quantitative proteomics identified 77 differentially expressed A. mellifera proteins (DEPs). In addition, viral proteins were identified by orthogonal analysis, and most importantly, Deformed wing virus (DWV) was found at high levels/intensity in Varroa-exposed bees. Pathway enrichment analysis suggested that the main pathways affected included peroxisomal metabolism, cyto-/exoskeleton reorganization, and cuticular proteins. Detailed examination of individual DEPs revealed that additional changes in DEPs were associated with peroxisomal function. In addition, the proteome data support the importance of TGF-ß signaling in Varroa-DWV interaction and the involvement of the mTORC1 and Hippo pathways. These results suggest that the effect of DWV on bees associated with Varroa feeding results in aberrant autophagy. In particular, autophagy is selectively modulated by peroxisomes, to which the observed proteome changes strongly corresponded. This study complements previous research with different study designs and suggests the importance of the peroxisome, which plays a key role in viral infections.

What proteomics has taught us about honey bee (Apis mellifera) health and disease.

The Western honey bee, Apis mellifera, is currently navigating a gauntlet of environmental pressures, including the persistent threat of parasites, pathogens, and climate change - all of which compromise the vitality of honey bee colonies. The repercussions of their declining health extend beyond the immediate concerns of apiarists, potentially imposing economic burdens on society through diminished agricultural productivity. Hence, there is an imperative to devise innovative monitoring techniques for assessing the health of honey bee populations. Proteomics, recognized for its proficiency in biomarker identification and protein-protein interactions, is poised to play a pivotal role in this regard. It offers a promising avenue for monitoring and enhancing the resilience of honey bee colonies, thereby contributing to the stability of global food supplies. This review delves into the recent proteomic studies of A. mellifera, highlighting specific proteins of interest and envisioning the potential of proteomics to improve sustainable beekeeping practices amidst the challenges of a changing planet.

Genomic diversity and population structure of Carniolan honey bee in its native habitat.

BACKGROUND: Research into the genetic diversity of honey bee (Apis mellifera L.) populations has become increasingly significant in recent decades, primarily due to population declines attributed to human activities and climate change. As a species of great importance, breeding programs that leverage understanding of genomic diversity could offer solutions to mitigate these challenges. The objective of this study was to examine the genomic diversity and population structure of Carniolan honey bees (Apis mellifera carnica) using the Illumina SNP chip on a large honey bee sample collected from Central and South-Eastern European countries. The study also aims to offer recommendations for future breeding programs. RESULTS: Our analysis involved Discriminant Analysis of Principal Components (DAPC), heterozygosity, admixture analysis, fixation indices (FST), Neighbour-Joining tree, gene flow and Isolation-by-distance analysis. DAPC indicated distinct separation between the Carniolan and Italian honey bee (Apis mellifera ligustica) populations, whereas the admixture analysis revealed varying levels of gene flow and genetic admixture within the Carniolan honey bee populations, demonstrating closer relationships between specific geographic regions (confirmed by Isolation-by-distance analysis). Furthermore, the research of heterozygosity, genomic inbreeding, pairwise FST values, and Neighbour-Joining tree provided insights into the patterns of genetic differentiation and similarity among the populations of Carniolan honey bee within its natural habitat. We have observed genetic homogeneity of the Carniolan honey bee population when considered in a broader genetic/geographical context. However, the Carniolan honey bee has sufficient genetic diversity in its geographical home range that needs to be carefully monitored and maintained. CONCLUSIONS: This study provides important insights into the genetic composition, differentiation, and relationships among Carniolan honey bee populations in Central and South-Eastern European countries. The findings are crucial for conservation efforts, breeding programs, and sustainable beekeeping practices. They emphasise the importance of considering genetic factors and population structure in the breeding and management of honey bees. By understanding these genetic relationships, we can develop strategies to preserve genetic diversity, improve breeding outcomes, and ensure the resilience of honey bee populations in the face of environmental changes and challenges. This knowledge can also inform policy makers and stakeholders on best practices to maintain healthy bee populations, which are vital for ecosystem services and agricultural productivity.

Regulatory roles of long non-coding RNAs in short-term heat stress in adult worker bees.

Long non-coding RNAs (lncRNAs) are crucial modulators of post-transcriptional gene expression regulation, cell fate determination, and disease development. However, lncRNA functions during short-term heat stress in adult worker bees are poorly understood. Here, we performed deep sequencing and bioinformatic analyses of honeybee lncRNAs. RNA interference was performed by using siRNA targeting the most highly expressed lncRNA. The silencing effect on lncRNA and the relative expression levels of seven heat shock protein (HSP) genes, were subsequently examined. Overall, 7,842 lncRNAs and 115 differentially expressed lncRNAs (DELs) were identified in adult worker bees following heat stress exposure. Structural analysis revealed that the overall expression abundance, length of transcripts, exon number, and open reading frames of lncRNAs were lower than those of mRNAs. GO analysis revealed that the target genes were mainly involved in "metabolism," "protein folding," "response to stress," and "signal transduction" pathways. KEGG analysis indicated that the "protein processing in endoplasmic reticulum" and "longevity regulating pathway-multiple species" pathways were most enriched. Quantitative real-time polymerase chain reaction (qRT-PCR) detection of the selected DELs confirmed the reliability of the sequencing data. Moreover, the siRNA experiment indicated that feeding siRNA yielded a silencing efficiency of 77.51% for lncRNA MSTRG.9645.5. Upon silencing this lncRNA, the expression levels of three HSP genes were significantly downregulated (p < 0.05), whereas those of three other HSP genes were significantly upregulated (p < 0.05). Our results provide a new perspective for understanding the regulatory mechanisms of lncRNAs in adult worker bees under short-term heat stress.

Stress-induced loss of social resilience in honeybee colonies and its implications on fitness.

Stressors may lead to a shift in the timing of life-history events of species, causing a mismatch with optimal environmental conditions, potentially reducing fitness. In honeybees, the timing of brood rearing and nest emergence in late winter/early spring is critical as colonies need to grow fast after winter to prepare for reproduction. However, the effects of stress on these life-history events in late winter/early spring and the possible consequences are not well understood. Therefore, we tested whether (i) honeybee colonies shift timing of brood rearing and nest emergence as response to stressors, and (ii) if there is a consequent loss of social resilience, reflected in colony fitness (survival, growth and reproduction). We monitored stressed (high load of the parasitic mite Varroa destructor or nutrition restricted) colonies and presumably non-stressed colonies from the beginning of 2020 till spring of 2021. We found that honeybee colonies do not shift the timing of brood rearing and nest emergence in spring as a coping mechanism to stressors. However, we show that there is loss of social resilience in stressed colonies, leading to reduced growth and reproduction. Our study contributes to better understanding the effects of stressors on social resilience in eusocial organisms.

In vitro activity of Western Australian honeys and Manuka honey against clinically important yeasts.

With the steady rise in antifungal resistance amongst clinically important yeasts, antifungal drug discovery remains of the utmost importance. To determine the potential of some honeys as alternative antifungal agents, we quantified the antifungal activity of 12 Western Australian honey samples, two Manuka honey samples and an artificial honey against 10 yeast isolates including clinical and reference strains. Results showed that the tested honeys varied in activity, and yeasts species also differed in susceptibility, with minimum inhibitory concentrations (MICs) determined by broth microdilution ranging from 8% to >44% w/v honey. Honeys with the highest overall activity were derived from Blackbutt (Eucalyptus patens), Jarrah (E. marginata), and Karri (E. diversicolor). The optical density of each MIC microtitre plate was determined after incubation and showed that at relatively low concentrations of honey the growth of all yeasts was enhanced compared to the untreated control, whereas at and above approximately 12% w/v, honeys exerted a dose-dependent growth inhibitory effect, the extent of which varied by honey type. Time-kill studies with 64% w/v honey showed that all eight of the natural honeys tested had greater fungicidal activity than the comparator artificial honey. Our findings suggest that the specific nectar-derived phytochemicals present within each honey play an important role in antifungal activity, and support the notion that activity is due to a combination of factors including osmotic activity, hydrogen peroxide and phytochemical compounds. These data indicate that honey is worthy of further investigation as a potential therapeutic agent for superficial yeast infections.

Crohn's disease-associated Escherichia coli LF82 in the gut damage of germ-free honeybees: A laboratory study.

Escherichia coli LF82 (LF82) is associated with Crohn's disease. The simplicity and genetic maneuverability of honeybees' gut microbiota make them suitable for studying host-microbe interactions. To understand the interaction between LF82 and host gut, LF82 was used to infect germ-free honeybees (Apis mellifera) orally. We found that LF82 successfully colonized the gut and shortened the lifespan of germ-free bees. LF82 altered the gut structure and significantly increased gut permeability. RT-qPCR showed that LF82 infection activated anti-infective immune pathways and upregulated the mRNAs levels of antimicrobial peptides in the gut of germ-free bees. The gut transcriptome showed that LF82 significantly upregulated genes involved in Notch signaling, adhesion junctions, and Toll and Imd signaling pathways and downregulated genes involved in the peroxisome proliferator-activated receptor (PPAR) signaling pathway, protein digestion and absorption, and tyrosine metabolism. In conclusion, the human-derived enteropathogenic bacterium LF82 can successfully colonize the gut of germ-free honeybees and cause enteritis-like changes, which provides an ideal model organism for revealing the pathogenesis of bacterial-associated diseases.

Transcriptome analysis of Apis mellifera antennae reveals molecular divergence underlying the division of labour in worker bees.

The olfactory system plays a fundamental role in mediating insect behaviour. Worker bees exhibit an age-dependent division of labour, performing discrete sets of behaviours throughout their lifespan. The behavioural states of bees rely on their sense of the environment and chemical communication via their olfactory system, the antennae. However, the olfactory adaptation mechanism of worker bees during their behavioural development remains unclear. In this study, we conducted a comprehensive and quantitative analysis of antennal gene expression in the Apis mellifera of newly emerged workers, nurses, foragers and defenders using RNA-seq. We found that the antenna tissues of honey bees continued developing after transformation from newly emerged workers to adults. Additionally, we identified differentially expressed genes associated with bee development and division of labour. We validated that major royal jelly protein genes are highly and specifically expressed in nurse honey bee workers. Furthermore, we identified and validated significant alternative splicing events correlated with the development and division of labour. These findings provide a comprehensive transcriptome profile and a new perspective on the molecular mechanisms that may underlie the worker honey bee division of labour.

Advances and knowledge gaps on climate change impacts on honey bees and beekeeping: A systematic review.

The Western honey bee Apis mellifera is a managed species that provides diverse hive products and contributing to wild plant pollination, as well as being a critical component of crop pollination systems worldwide. High mortality rates have been reported in different continents attributed to different factors, including pesticides, pests, diseases, and lack of floral resources. Furthermore, climate change has been identified as a potential driver negatively impacting pollinators, but it is still unclear how it could affect honey bee populations. In this context, we carried out a systematic review to synthesize the effects of climate change on honey bees and beekeeping activities. A total of 90 articles were identified, providing insight into potential impacts (negative, neutral, and positive) on honey bees and beekeeping. Interest in climate change's impact on honey bees has increased in the last decade, with studies mainly focusing on honey bee individuals, using empirical and experimental approaches, and performed at short-spatial (<10 km) and temporal (<5 years) scales. Moreover, environmental analyses were mainly based on short-term data (weather) and concentrated on only a few countries. Environmental variables such as temperature, precipitation, and wind were widely studied and had generalized negative effects on different biological and ecological aspects of honey bees. Food reserves, plant-pollinator networks, mortality, gene expression, and metabolism were negatively impacted. Knowledge gaps included a lack of studies at the apiary and beekeeper level, a limited number of predictive and perception studies, poor representation of large-spatial and mid-term scales, a lack of climate analysis, and a poor understanding of the potential impacts of pests and diseases. Finally, climate change's impacts on global beekeeping are still an emergent issue. This is mainly due to their diverse effects on honey bees and the potential necessity of implementing adaptation measures to sustain this activity under complex environmental scenarios.

La abeja occidental Apis mellifera es una especie manejada que proporciona diversos productos de la colmena y servicios de polinización, los cuales son cruciales para plantas silvestres y cultivos en todo el mundo. En distintos continentes se han registrado altas tasas de mortalidad, las cuales son atribuidas a diversos factores, como el uso de pesticidas, plagas, enfermedades y falta de recursos florales. Además, el cambio climático ha sido identificado como un potencial factor que afecta negativamente a los polinizadores, pero aún no está claro cómo podría afectar a las poblaciones de abejas melíferas. En este contexto, realizamos una revisión sistemática de la literatura disponible para sintetizar los efectos del cambio climático en las abejas melíferas y las actividades apícolas. En total, se identificaron 90 artículos que proporcionaron información sobre los posibles efectos (negativos, neutros y positivos) en las abejas melíferas y la apicultura. El interés por el impacto del cambio climático en las abejas melíferas ha aumentado en la última década, con estudios centrados principalmente en individuos de abejas melíferas, utilizando enfoques empíricos y experimentales y realizados a escalas espaciales (<10 km) y temporales (<5 años) cortas. Además, los análisis ambientales fueron basaron principalmente en datos a corto plazo (meteorológicos) y se concentraron sólo en algunos países. Variables ambientales como la temperatura, las precipitaciones y el viento fueron ampliamente estudiadas y tuvieron efectos negativos generalizados sobre distintos aspectos biológicos y ecológicos de las abejas melíferas. Además, las reservas alimenticias, las interacciones planta-polinizador, la mortalidad, la expresión génica y el metabolismo se vieron afectados negativamente. Entre los vacios de conocimiento cabe mencionar la falta de estudios a nivel de colmenar y apicultor, la escasez de estudios de predicción y percepción, la escasa representación de las grandes escalas espaciales y a mediano plazo, el déficit de análisis climáticos y la escasa comprensión de los impactos potenciales de plagas y enfermedades. Por último, las repercusiones del cambio climático en la apicultura mundial siguen siendo un tema emergente, que debe estudiarse en los distintos países. Esto se debe principalmente a sus diversos efectos sobre las abejas melíferas y a la necesidad potencial de aplicar medidas de adaptación para mantener esta actividad crucial en escenarios medioambientales complejos.

Age-related flexibility of energetic metabolism in the honey bee Apis mellifera.

The mechanisms that underpin aging are still elusive. In this study, we suggest that the ability of mitochondria to oxidize different substrates, which is known as metabolic flexibility, is involved in this process. To verify our hypothesis, we used honey bees (Apis mellifera carnica) at different ages, to assess mitochondrial oxygen consumption and enzymatic activities of key enzymes of the energetic metabolism as well as ATP5A1 content (subunit of ATP synthase) and adenylic energy charge (AEC). We also measured mRNA abundance of genes involved in mitochondrial functions and the antioxidant system. Our results demonstrated that mitochondrial respiration increased with age and favored respiration through complexes I and II of the electron transport system (ETS) while glycerol-3-phosphate (G3P) oxidation was relatively decreased. In addition, glycolytic, tricarboxylic acid cycle and ETS enzymatic activities increased, which was associated with higher ATP5A1 content and AEC. Furthermore, we detected an early decrease in the mRNA abundance of subunits of NADH ubiquinone oxidoreductase subunit B2 (NDUFB2, complex I), mitochondrial cytochrome b (CYTB, complex III) of the ETS as well as superoxide dismutase 1 and a later decrease for vitellogenin, catalase and mitochondrial cytochrome c oxidase subunit 1 (COX1, complex IV). Thus, our study suggests that the energetic metabolism is optimized with aging in honey bees, mainly through quantitative and qualitative mitochondrial changes, rather than showing signs of senescence. Moreover, aging modulated metabolic flexibility, which might reflect an underpinning mechanism that explains lifespan disparities between the different castes of worker bees.

A versatile recording device for the analysis of continuous daily external activity in colonies of highly eusocial bees.

As pollinators, bees are key to maintaining the biodiversity of angiosperm plants, and for agriculture they provide a billion-dollar ecosystem service. But they also compete for resources (primarily nectar and pollen), especially the highly social bees that live in perennial colonies. So, how do they organize their daily temporal activities? Here, we present a versatile, low-cost device for the continuous, automatic recording and data analysis of the locomotor activity in the colony-entrance tube of highly eusocial bees. Consisting of an in-house built block containing an infrared detector, the passage of bees in the colony entrance tunnel is registered and automatically recorded in an Arduino environment, together with concomitant recordings of temperature and relative humidity. With a focus on the highly diverse Neotropical stingless bees (Meliponini), we obtained 10-day consecutive recordings for two colonies each of the species Melipona quadrifasciata and Frieseomelitta varia, and also for the honey bee. The Lomb-Scargle periodogram analysis identified a predominant circadian rhythmicity for all three species, but also indications of ultradian rhythms. For M. quadrifasciata, which is comparable in size to the honey bee, we found evidence for a possibly anticipatory activity already before sunrise. As all three species also presented activity at night in the colony entrance tube, this also raises questions about sleep organization in social insects. The cost and versatility of the device and the open-source options for data analysis make this an attractive system for conducting studies on circadian rhythms in social bees under natural conditions, complementing studies on flower visits by these important pollinators.

The buzz within: the role of the gut microbiome in honeybee social behavior.

Gut symbionts influence the physiology and behavior of their host, but the extent to which these effects scale to social behaviors is an emerging area of research. The use of the western honeybee (Apis mellifera) as a model enables researchers to investigate the gut microbiome and behavior at several levels of social organization. Insight into gut microbial effects at the societal level is critical for our understanding of how involved microbial symbionts are in host biology. In this Commentary, we discuss recent findings in honeybee gut microbiome research and synthesize these with knowledge of the physiology and behavior of other model organisms to hypothesize how host-microbe interactions at the individual level could shape societal dynamics and evolution.

Learning performance and GABAergic pathway link to deformed wing virus in the mushroom bodies of naturally infected honey bees.

Viral infections can be detrimental to the foraging ability of the western honey bee, Apis mellifera. The deformed wing virus (DWV) is the most common honey bee virus and has been proposed as a possible cause of learning and memory impairment. However, evidence for this phenomenon so far has come from artificially infected bees, while less is known about the implications of natural infections with the virus. Using the proboscis extension reflex (PER), we uncovered no significant association between a simple associative learning task and natural DWV load. However, when assessed through a reversal associative learning assay, bees with higher DWV load performed better in the reversal learning phase. DWV is able to replicate in the honey bee mushroom bodies, where the GABAergic signalling pathway has an antagonistic effect on associative learning but is crucial for reversal learning. Hence, we assessed the pattern of expression of several GABA-related genes in bees with different learning responses. Intriguingly, mushroom body expression of selected genes was positively correlated with DWV load, but only for bees with good reversal learning performance. We hypothesise that DWV might improve olfactory learning performance by enhancing the GABAergic inhibition of responses to unrewarded stimuli, which is consistent with the behavioural patterns that we observed. However, at higher disease burdens, which might be induced by an artificial infection or by a severe, natural Varroa infestation, this DWV-associated increase in GABA signalling could impair associative learning as previously reported by other studies.

A thermal performance curve perspective explains decades of disagreements over how air temperature affects the flight metabolism of honey bees.

While multiple studies have shown that honey bees and some other flying insects lower their flight metabolic rates when flying at high air temperatures, critics have suggested such patterns result from poor experimental methods as, theoretically, air temperature should not appreciably affect aerodynamic force requirements. Here, we show that apparently contradictory studies can be reconciled by considering the thermal performance curve of flight muscle. We show that prior studies that found no effects of air temperature on flight metabolism of honey bees achieved flight muscle temperatures that were near or on equal, opposite sides of the thermal performance curve. Honey bees vary their wing kinematics and metabolic heat production to thermoregulate, and how air temperature affects the flight metabolic rate of honey bees is predictable using a non-linear thermal performance perspective of honey bee flight muscle.

Bifidobacterium apis sp. nov., isolated from the gut of honeybee (Apis mellifera).

A novel bifidobacterium (designated F753-1T) was isolated from the gut of honeybee (Apis mellifera). Strain F753-1T was characterized using a polyphasic taxonomic approach. Strain F753-1T was phylogenetically related to the type strains of Bifidobacterium mizhiensis, Bifidobacterium asteroides, Bifidobacterium choladohabitans, Bifidobacterium mellis, Bifidobacterium apousia and Bifidobacterium polysaccharolyticum, having 98.4-99.8 % 16S rRNA gene sequence similarities. The phylogenomic tree indicated that strain F753-1T was most closely related to the type strains of B. mellis and B. choladohabitans. Strain F753-1T had the highest average nucleotide identity (94.1-94.5 %) and digital DNA-DNA hybridization (56.3 %) values with B. mellis Bin7NT. Acid production from amygdalin, d-fructose, gentiobiose, d-mannose, maltose, sucrose and d-xylose, activity of α-galactosidase, pyruvate utilization and hydrolysis of hippurate could differentiate strain F753-1T from B. mellis CCUG 66113T and B. choladohabitans JCM 34586T. Based upon the data obtained in the present study, a novel species, Bifidobacterium apis sp. nov., is proposed, and the type strain is F753-1T (=CCTCC AB 2023227T=JCM 36562T=LMG 33388T).