Bee Gut Research Articles

Targeting the honey bee gut parasite Nosema ceranae with siRNA positively affects gut bacteria

BackgroundGut microbial communities can contribute positively and negatively to host health. So far, eight core bacterial taxonomic clusters have been reported in honey bees. These bacteria are involved in host metabolism and defenses. Nosema ceranae is a gut intracellular parasite of honey bees which destroys epithelial cells and gut tissue integrity. Studies have shown protective impacts of honey bee gut microbiota towards N. ceranae infection. However, the impacts of N. ceranae on the relative abundance of honey bee gut microbiota remains unclear, and has been confounded during prior infection assays which resulted in the co-inoculation of bacteria during Nosema challenges. We used a novel method, the suppression of N. ceranae with specific siRNAs, to measure the impacts of Nosema on the gut microbiome.ResultsSuppressing N. ceranae led to significant positive effects on microbial abundance. Nevertheless, 15 bacterial taxa, including three core taxa, were negatively correlated with N. ceranae levels. In particular, one co-regulated group of 7 bacteria was significantly negatively correlated with N. ceranae levels.ConclusionsN. ceranae are negatively correlated with the abundance of 15 identified bacteria. Our results provide insights into interactions between gut microbes and N. ceranae during infection.

Impact of Glyphosate on the Honey Bee Gut Microbiota: Effects of Intensity, Duration, and Timing of Exposure.

Exposure to anthropogenic chemicals may indirectly compromise animal health by perturbing the gut microbiota. For example, the widely used herbicide glyphosate can affect the microbiota of honey bees, reducing the abundance of beneficial bacterial species that contribute to immune regulation and pathogen resistance. Previous studies have not addressed how this impact depends on concentration, duration of exposure, or stage of microbiota establishment. Worker bees acquire their microbiota from nestmates early in adult life, when they can also be exposed to chemicals collected by foragers or added to the hives. Here, we investigated how the gut microbiota of honey bees is affected by different concentrations of glyphosate and compared the effects with those caused by tylosin, an antibiotic commonly used to treat hives. We treated newly emerged workers at the stage at which they acquire the microbiota and also workers with established gut microbiota. Treatments consisted of exposure to sucrose syrup containing glyphosate in concentrations ranging from 0.01 mM to 1.0 mM or tylosin at 0.1 mM. Based on 16S rRNA amplicon sequencing and quantitative PCR (qPCR) determination of abundances, glyphosate perturbed the gut microbiota of honey bees regardless of age or period of exposure. Snodgrassella alvi was the most affected bacterial species and responded to glyphosate in a dose-dependent way. Tylosin also perturbed the microbiota, especially at the stage of acquisition, and the effects differed sharply from the effects of glyphosate. These findings show that sublethal doses of glyphosate (0.04 to 1.0 mM) and tylosin (0.1 mM) affect the microbiota of honey bees.IMPORTANCE As is true of many animal species, honey bees depend on their gut microbiota for health. The bee gut microbiota has been shown to regulate the host immune system and to protect against pathogenic diseases, and disruption of the normal microbiota leads to increased mortality. Understanding these effects can give broad insights into vulnerabilities of gut communities, and, in the case of honey bees, could provide information useful for promoting the health of these economically critical insects, which provide us with crop pollination services as well as honey and other products. The bee gut microbiota is acquired early in adult life and can be compromised by antibiotics and other chemicals. The globally used weed killer glyphosate was previously found to impact the gut microbiota of honey bees following sustained exposure. In the present study, we address how this impact depends on concentration, duration of exposure, and stage of community establishment. We found that sublethal doses of glyphosate reduce the abundance of beneficial bacteria and affect microbial diversity in the guts of honey bees, regardless of whether exposure occurs during or after microbiota acquisition. We also compared the effects of glyphosate to those of tylosin, an antibiotic used in beekeeping, and observed that tylosin effects diverge from those caused by glyphosate and are greater during microbiota acquisition. Such perturbations are not immediately lethal to bees but, depending on exposure level, can decrease survivorship under laboratory conditions.

Health endorsing potential of Lactobacillus plantarum MBTU-HK1 and MBTU-HT of Honey bee gut origin

Lactobacillus plantarum, is considered as an evergreen beckoning of probiotics. The literature available on the health benefits of L. plantarum within the gut, Apis cerana indica is very limited. The present study explores the health benefits of L. plantarum in Apis cerana indica (Indian honey bee). The study aimed to determine the health endorsing role of probiotic strains MBTU-HK1 and MBTU-HT (Accession no: KX519413 and KX519414) existed in the gut, Apis cerana indica. In the current study, the functionality among strains was evaluated in vitro for bile salt hydrolase (BSH) activity, Hypercholesteraemic activity, β-galactosidase activity, antioxidative potential, angiotensin-converting enzyme (ACE) inhibitory potency, and Folate production. The test strains possess BSH activity and anti-cholesteric activity, testifying to a role in cholesterol removal. The production of β-galactosidase enzyme suggested that they are effective in the improvement of lactose intolerance. The antioxidant activity revealed their effective free radical scavenging activity. The ACE inhibitory potency indicated their involvement in blood pressure control. The ability to produce folate by the test strains was also verified. The current investigation proves probiotic role with health benefits among MBTU-HK1 and MBTU HT in reducing risks associated with cardiovascular diseases, lactose intolerance, and hypertension management.

Impact of air pollution on buff-tailed bumblebees (Bombus terrestris) and their gut microbiome

Bumblebees play a major role in global pollination. Consequently, their health is of high importance for food security worldwide. Yet, recent population estimates show that their numbers are declining. This decline has been attributed to habitat loss, infection and use of pesticides. An important factor for bee health that contributes to population survival is the gut microbiome composition. The bee gut microbiome provides protection from pathogens, is specific to the host and helps break down food. Without a balanced gut microbiome, the health of the bee is threatened through increased infection and mortality. The bee gut microbiome is relatively simple, being dominated by 8 core bacterial species providing a convenient study system. Previous published data shows that air pollution has an impact on bacterial behaviour. Therefore, our hypothesis is exposure to air pollution causes an imbalance in the bee gut microbiome. To test this, we exposed bees to black carbon (BC), a major component of air pollution particulate matter. We assessed the effects on bee behaviour, microbiome composition and gut bacteria treated in vitro. Bees treated with BC showed a significant increase in viable bacterial cells in their faecal community. Independent culture of gut commensals showed that BC significantly alters the structure of their biofilms, which are important for colonisation in vivo. This supports the hypothesis that air pollution can cause an imbalance in the bee gut microbiome, and may adversely influence bee health and pollinator populations.

Shotgun sequencing of honey DNA can describe honey bee derived environmental signatures and the honey bee hologenome complexity

Honey bees are large-scale monitoring tools due to their extensive environmental exploration. In their activities and from the hive ecosystem complex, they get in close contact with many organisms whose traces can be transferred into the honey, which can represent an interesting reservoir of environmental DNA (eDNA) signatures and information useful to analyse the honey bee hologenome complexity. In this study, we tested a deep shotgun sequencing approach of honey DNA coupled with a specifically adapted bioinformatic pipeline. This methodology was applied to a few honey samples pointing out DNA sequences from 191 organisms spanning different kingdoms or phyla (viruses, bacteria, plants, fungi, protozoans, arthropods, mammals). Bacteria included the largest number of species. These multi-kingdom signatures listed common hive and honey bee gut microorganisms, honey bee pathogens, parasites and pests, which resembled a complex interplay that might provide a general picture of the honey bee pathosphere. Based on the Apis mellifera filamentous virus genome diversity (the most abundant detected DNA source) we obtained information that could define the origin of the honey at the apiary level. Mining Apis mellifera sequences made it possible to identify the honey bee subspecies both at the mitochondrial and nuclear genome levels.

Prospects and Validity of Laboratory Cage Tests Conducted in Honeybee Research Part Two: New Possibilities for Use of Laboratory Cage Tests in Response to Challenges Revealed at the Turn of the 20th and 21st Centuries

Abstract Nowadays, cell cultures are a standard tool in animal biotechnology, but the problem with honeybees is the constant lack of appropriate cell lines to be used in in vitro research. Until the imperfections of bee tissue cultures are resolved, researchers have to conduct experiments on bees in laboratory cage tests (LCTs). At the turn of the 21st century many new hazards for beekeeping appeared. An early recognized problem was the Colony Collapse Disorder and Honey Bee Depopulation Syndrome, which were associated with the harmfulness of pesticides and strictly linked with a decline in bee immunity. Such problems in LCTs were attempted to be resolved through research on the interactions between biostimulators and antiparasitic drugs. LCTs allow the relationship between the dose of a specific factor and its impact to be determined, which can be used in the establishment of reference values. Furthermore, LCTs may be a useful tool in understanding the function and role of bee gut flora. Using the honeybee as an animal model is possible thanks to knowledge of the honeybee genome and bee biology and the similarity between some physiological and biochemical processes and those occurring in humans. So far, LCTs have been used to understand better human aging, learning and gene expression regulating. This is facilitated by the advanced development of medicine and molecular genetics, and in the future the use of honeybees may become a standard in biochemical or gerontological research.

Probing the Honey Bee Diet-Microbiota-Host Axis Using Pollen Restriction and Organic Acid Feeding.

Microbial metabolites are considered important drivers of diet-based microbiota influence on the host, however, mechanistic models are confounded by interactions between diet, microbiota function, and host physiology. The honey bee harbors a simple microbiota that produces organic acids as fermentation products of dietary nectar and pollen, making it a model for gut microbiota research. Herein, we demonstrate that bacterial abundance in the honey bee gut is partially associated with the anterior rectum epithelium. We used dietary pollen restriction and organic acid feeding treatments to obtain information about the role of undigested pollen as a microbiota growth substrate and the impact of bacterial fermentation products on honey bee enteroendocrine signaling. Pollen restriction markedly reduced total and specific bacterial 16S rRNA abundance in the anterior rectum but not in the ileum. Anterior rectum expression levels of bacterial fermentative enzyme gene transcripts (acetate kinase, lactate dehydrogenase, and hydroxybutyryl-CoA dehydrogenase) were reduced in association with diet-induced microbiota shifts. To evaluate the effects of fermentative metabolites on host enteroendocrine function, pollen-restricted bees were fed an equimolar mixture of organic acid sodium salts (acetate, lactate, butyrate, formate, and succinate). Organic acid feeding significantly impacted hindgut enteroendocrine signaling gene expression, rescuing some effects of pollen restriction. This was specifically manifested by tissue-dependent expression patterns of neuropeptide F and allatostatin pathways, which are implicated in energy metabolism and feeding behaviors. Our findings provide new insights into the diet-microbiota-host axis in honey bees and may inform future efforts to improve bee health through diet-based microbiota manipulations.

Honey bee (Apis mellifera) gut microbiota promotes host endogenous detoxification capability via regulation of P450 gene expression in the digestive tract.

SummaryThere is growing number of studies demonstrating a close relationship between insect gut microbiota and insecticide resistance. However, the contribution of the honey bee gut microbiota to host detoxification ability has yet to be investigated. In order to address this question, we compared the expression of cytochrome P450s (P450s) genes between gut microbiota deficient (GD) workers and conventional gut community (CV) workers and compared the mortality rates and the pesticide residue levels of GD and CV workers treated with thiacloprid or tau‐fluvalinate. Our results showed that gut microbiota promotes the expression of P450 enzymes in the midgut, and the mortality rate and pesticide residue levels of GD workers are significantly higher than those of CV workers. Further comparisons between tetracycline‐treated workers and untreated workers demonstrated that antibiotic‐induced gut dysbiosis leads to attenuated expression of P450s in the midgut. The co‐treatment of antibiotics and pesticides leads to reduced survival rate and a significantly higher amount of pesticide residues in honey bees. Taken together, our results demonstrated that honey bee gut symbiont could contribute to bee health through the modification of the host xenobiotics detoxification pathways and revealed a potential negative impact of antibiotics to honey bee detoxification ability and health.

Competition and Identification of Anaerobic Organisms Isolated from Apis mellifera Gut Microbiota

Apis mellifera, the most common species of honeybee, has been suffering the epidemic of colony collapse disorder (CCD). This is defined by the sudden and unexplainable death of an entire colony of bees, and populations worldwide dwindle further every year. Although research continues, there exists no lasting or effective treatment. One underdeveloped area of study has been the option to treat bees with probiotics ( Audisio, 2017; Baffoni et al., 2015). There have been numerous studies within other organisms and honeybees that show that a well‐maintained gut microbiome is a key component of health, especially when the pathogen is endemic to the intestines – as in the case of Nosema pathogen, which has been implicated in CCD ( Raymann, 2018; Shreiner, 2015). The hypothesis being investigated is that microbes cultivated from the gut of normal bees will suppress the growth of known honey bee pathogens. Identification of such normal flora may serve as a probiotic for treatment of bees experiencing CCD due to infectious agents.Support or Funding InformationResearch Grant from the University of Wisconsin ‐ Stout

Comparative genomics of Lactobacillus species as bee symbionts and description of Lactobacillus bombintestini sp. nov., isolated from the gut of Bombus ignitus.

The Lactobacillus genus is widely used for fermentation of plant materials and dairy products. These species are typically found in highly specialized environments, with the bee gut serving as one of the niche locations in which Lactobacillus is detected. Lactobacillus species isolated from the bee gut and bee-related habitats were phylogenetically classified into three distinct groups, Lactobacillus kunkeei, Firm-4, and Firm-5. The L. kunkeei group was clearly differentiated from other members of the Lactobacillus buchneri group isolated from non-bee habitats. In comparison with non-bee members of the L. buchneri group, three bee-symbiotic Lactobacillus groups had a small-sized genome with low G + C content and showed a sharp reduction in the number of genes involved in energy production, carbohydrate transport and metabolism, and amino acid transport and metabolism. In addition, all three groups lacked the mutY gene, which encodes A/G-specific adenine glycosylase. The phylogenetic dendrogram based on the presence or absence of 1,199 functional genes indicated that these bee-symbiotic groups experienced convergent evolution. The occurrence of convergent evolution is thought to stem from the three bee-symbiotic groups sharing a similar habitat, i.e., the bee gut. The causative factor underlying genomic reduction was postulated to be mutY, which was absent in all three groups. Here, a novel strain, BHWM-4T, isolated from the gut of Bombus ignites was studied using polyphasic taxonomy and classified as a new member of the L. kunkeei group. The strain was Gram-positive, facultative anaerobic, and rod-shaped. The 16S ribosomal RNA gene sequence and genome analysis revealed that strain BHWM-4T was clustered into the L. kunkeei group, forming a compact cluster with L. kunkeei and Lactobacillus apinorum. Biochemical, chemotaxonomic, and genotypic data of strain BHWM-4T supports the proposal of a novel species, Lactobacillus bombintestini sp. nov., whose type strain is BHWM-4T (= KACC 19317 = NBRC 113067T).

Honey bees harbor a diverse gut virome engaging in nested strain-level interactions with the microbiota

The honey bee gut microbiota influences bee health and has become an important model to study the ecology and evolution of microbiota-host interactions. Yet, little is known about the phage community associated with the bee gut, despite its potential to modulate bacterial diversity or to govern important symbiotic functions. Here we analyzed two metagenomes derived from virus-like particles, analyzed the prevalence of the identified phages across 73 bacterial metagenomes from individual bees, and tested the host range of isolated phages. Our results show that the honey bee gut virome is composed of at least 118 distinct clusters corresponding to both temperate and lytic phages and representing novel genera with a large repertoire of unknown gene functions. We find that the phage community is prevalent in honey bees across space and time and targets the core members of the bee gut microbiota. The large number and high genetic diversity of the viral clusters seems to mirror the high extent of strain-level diversity in the bee gut microbiota. We isolated eight lytic phages that target the core microbiota member Bifidobacterium asteroides, but that exhibited different host ranges at the strain level, resulting in a nested interaction network of coexisting phages and bacterial strains. Collectively, our results show that the honey bee gut virome consists of a complex and diverse phage community that likely plays an important role in regulating strain-level diversity in the bee gut and that holds promise as an experimental model to study bacteria-phage dynamics in natural microbial communities.

Could honey bees signal the spread of antimicrobial resistance in the environment?

The honey bee has long been known to be a bioindicator of environmental pollution and the use of antimicrobials in the beekeeping industry is strictly regulated. For these reasons, this paper was aimed to evaluate for the first time the role of Apis mellifera as a possible indicator of environmental antimicrobial resistance (AMR). The study isolated and analysed the resistance patterns of Enterobacteriaceae from a pool of honey bee guts located in five different environmental sites (ES), where different antimicrobial selective pressures were hypothesized. In all, 48 isolates were considered for identification and underwent analyses of AMR to ampicillin, amoxicillin/clavulanic acid, cefazolin, ceftazidime, tetracycline, imipenem, enrofloxacin, amikacin and trimethoprim/sulfamethoxazole. In all, 12 isolates out of 48 (25%) showed resistance to at least one antimicrobial drug. There were no significant differences between the resistance rates observed in the ESs, even if the highest percentage of resistance was found in ES4. Resistances to amoxicillin/clavulanic acid resulted significantly higher than those detected towards the other antimicrobials. Amoxicillin/clavulanic acid is not commonly used in beekeeping but it is extensively used in animals and in humans, suggesting an environmental origin of this resistance and supporting the hypothesis that honey bees could be used as indicators of AMR spread in the environment. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, a possible role of honey bees as indicator of environmental antimicrobial resistance is hypothesized. Enterobacteriaceae were isolated from bees living in different environmental sites (ES) where different antimicrobial selective pressures were hypothesized. Even if no differences between the resistances in the five ES were observed, the resistance rates for amoxicillin/clavulanic acid, compared to other antimicrobials, were significantly higher. Since amoxicillin/clavulanic acid is not used in beekeeping but it is extensively used in animals and in humans, an environmental origin of this resistance is suggested that supports our hypothesis.

Nicotine does not reduce Nosema ceranae infection in honey bees

Bee-collected pollen and nectar contain multiple phytochemicals that can have anti-pathogenic effects when ingested. For example, the plant alkaloid, nicotine, can reduce infections by the trypanosome gut parasite (Crithidia bombi) in bumblebees. Parasitized bumblebees may be drawn to nicotine and thereby self-medicate their infection. We tested the hypothesis that nicotine can reduce infections of a common microsporidian pathogen, Nosema ceranae, in the honey bee gut. We found, however, that that a field realistic exposure dose of 1 ppm nicotine was not preferentially consumed by Apis mellifera foragers fed live Nosema spores (5 × 104 spores per bee; N = 160). One-day-old bees infected with Nosema (1 × 104 spores per bee; N = 160) showed no repression of nosemosis over a chronically applied exposure gradient of 0, 10−2, 10−1, 100, 101, 102, 103 or 104 ppm nicotine. Since imbibed nicotine may not effectively reach the spores in the bee gut, we conducted an in vitro experiment, in which Nosema spores were exposed up to 104 ppm nicotine in vials, rinsed of nicotine, and then fed to 1 day old bees (2 × 104 spores per bee; N = 216). However, the in vitro nicotine-treated spores remained infectious. Nicotine did impair bee mortality at high concentrations. Dietary nicotine is evidently not a treatment for nosemosis, but future studies should continue to examine the role of phytochemicals and bee health.

Propolis hosts a diversemicrobial community.

Despite the deep knowledge of the honey bee (Apis mellifera) gut microbiome, information on the microbial communities of other hive components is still scarce. Propolis originates from a natural resinous mixture that honeybees collect from different plants sources and modify; it is used mainly to ensure the hygiene of the hive. By virtue of its antimicrobial properties, propolis has been considered relatively aseptic, yet its ability to harbor microorganisms has not been previously investigated. In this study we report the first description of the diversity of the microbial community of propolis by both targeted-metagenomics analysis and cultivation. We demonstrated that propolis hosts a variety of microbial strains belonging to taxa already described in other hive components. Some of them are cultivable in standard laboratory conditions, and show metabolic characteristics compatible with their persistence in different physiological states inside propolis. Isolated bacteria produce antimicrobials against Gram-negative and Gram-positive bacteria, and entomopathogenic fungi, with different spectra of inhibition. Metagenomics analysis shows the presence of bacteria and fungi with great potential to outcompete potentially harmful microorganisms. These findings suggest that the characterized microbiota could contribute to the overall antimicrobial properties of propolis and to its ecological role as "disinfectant" within the hive.

Modified bugs boost bee health.

Pathogens are wreaking havoc on bee populations. A study in Science describes how bacteria in the guts of bees can be engineered to protect their hosts from two particular pests, deformed wing virus and Varroa mites.

A microbiome silver bullet for honey bees.

A genetically engineered honey bee gut bacterium knocks down two major bee threats

In vitro antagonistic potential of gut bacteria isolated from indigenous honey bee race of Saudi Arabia against Paenibacillus larvae

Paenibacillus larvae is one of the major bacterial pathogens of honey bee broods and the causative agent of American foulbrood (AFB) disease. The factors responsible for the pathogenesis of AFB disease are still not fully understood, and the increasing resistance of P. larvae to commonly used antibiotics requires a search for new agents to control this disease. An in vitro screen was carried out to determine the antagonistic activity of gut bacteria isolated from indigenous honey bees, Apis mellifera jemenitica of Saudi Arabia against P. larvae. The gut bacterial isolates were evaluated individually against P. larvae ATCC9545 strain by the disc diffusion method. Seven of the 100 evaluated gut bacterial isolates, Fructobacillus fructosus (KY027123); Proteus mirabilis (KY027132); Bacillus licheniformis (KY027142); Lactobacillus kunkeei (KY027158); Bacillus subtilis (KY027169); Enterobacter kobei (KY027178); and Morganella morganii (KY027186) showed strong inhibitory effects. To our knowledge, this the first demonstration of antagonistic activity of F. fructosus, P. mirabilis, E. kobei, and M. morganii isolated from honey bee gut against P. larvae. The tested gut isolates exhibited significant antimicrobial activities against P. larvae, and they could play an important role in the treatment or prevention of AFB disease.

Diverging landscape impacts on macronutrient status despite overlapping diets in managed (Apis mellifera) and native (Melissodes desponsa) bees.

Declining pollinator populations worldwide are attributed to multiple stressors, including the loss of quality forage. Habitat management in agricultural areas often targets honey bees (Apis mellifera L.) specifically, with the assumption that native bees will benefit from an 'umbrella species' strategy. We tested this theory using a conservation physiology approach to compare the effects of landscape composition and floral dietary composition on the physiological status of honey bees and Melissodes desponsa in eastern South Dakota, USA. The total glycogen, lipid and protein concentrations were quantified from field collected bees. Next-generation sequencing of the trnL chloroplast gene from bee guts was used to evaluate dietary composition. The effects of landscape and dietary composition on macronutrient concentrations were compared between bee species. As the mean land-use patch area increased, honey bee glycogen levels increased, though M. desponsa experienced a decrease in glycogen. Protein levels decreased in honey bees as the largest patch index, a measure of single patch dominance, increased versus M. desponsa. Lipids in both species were unaffected by the measured landscape variables. Dietary analysis revealed that honey bees foraged preferentially on weedy non-native plant species, while M. desponsa sought out native and rarer species, in addition to utilizing non-native plants. Both species foraged on Asteraceae, Oleaceae and Fabaceae, specifically Melilotus sp. and Medicago sp. Dietary composition was not predictive of the macronutrients measured for either species. Together, these data highlight the management importance of including patch area in conservation recommendations, as bee species may have divergent physiological responses to landscape characteristics. While solitary bees may forage on weedy introduced plants in agricultural areas, robust strategies should also reincorporate native plant species, though they may not be preferred by honey bees, to maximize overall health and diversity of pollinator communities.

The Impact of Yeast Presence in Nectar on Bumble Bee Behavior and Fitness

The presence of yeasts in pollen and floral nectar is rather the norm than the exception. Due to the metabolic activities of yeasts, sugar and amino acid composition of nectar often drastically change and may negatively impact the nutritional value of nectar for pollinators and hence insect fitness. On the other hand, the presence of yeasts in floral nectar may also increase its nutritional value due to yeast's probiotic effect and the release of yeast's metabolites. In this study, we investigated whether the presence of defined flower‐ and insect‐associated yeasts affected individual and colony fitness of the bumble bee pollinator Bombus terrestris. Specifically, we tested whether the presence of yeasts in nectar affected bumble bee foraging behavior and nectar consumption, individual growth and colony development, larval and queen mortality, and mating success. Quantitative analyses of sugar and amino acid profiles showed that nectar yeasts significantly affected the chemical composition of nectar. However, dual‐choice experiments indicated that yeast inoculation did not significantly affect foraging behavior or consumption rates. Nest development, on the other hand, was significantly affected by the presence of yeasts, but effects largely depended on species identity, with Candida bombiphila, Metschnikowia gruessii, and Rhodotorula mucilaginosa having the largest positive impact on colony growth. Interestingly, the effects at the colony level were more pronounced than at the individual level. In vitro growth tests further showed that yeasts have the potential to suppress the growth of the bumble bee gut pathogen Crithidia bombi. Overall, these results demonstrate that nectar‐inhabiting yeasts can have diverse effects on bumble bee fitness and therefore may mediate plant–pollinator mutualisms.

Sharing the work.

This study investigated the ability of individual members of the bee gut microbiota to digest polysaccharides.