Worker Honeybees Research Articles

Long‐term risk assessment on noneffective and effective toxic doses of imidacloprid to honeybee workers

AbstractImidacloprid is the most widely used insecticide in agriculture. Its impact on honeybees has received worldwide attention. Foliar sprays are commonly and frequently used for piercing insect control, particularly on cotton in southern USA. To simulate field exposures of formulated imidacloprid (Advise® 2Fl), we used a modified spray tower to treat honeybee workers and monitored five enzyme activities and survival for up to 52 days. Results indicated that spray treatments twice a week for 52 days with 0.001 and 1 mg/L and once a week for three weeks with 4.3 mg/L Advise showed no adverse effect on bee survival, where imidacloprid‐treated bees could live as long as untreated bees. Concentration ≥80 mg/L significantly reduced bee survival, and substantial number of bees continued to die after 48‐hr of post‐treatment period which was commonly used for measuring insecticide toxicity. The body weight of imidacloprid‐treated bees (at LC20 and LC50) was also significantly reduced. Enzymatic data showed that activities of detoxification enzymes esterase and glutathione S‐transferase (GST), insecticide‐target enzyme acetylcholinesterase (AChE) and honey enzyme invertase in imidacloprid‐treated survivors were mostly similar to those found in untreated bees. The immunity‐related phenoloxidase (PO) activity in imidacloprid‐treated survivors was also mostly similar to that of untreated control, but higher PO activity was detected in bees treated with higher concentrations for 3 weeks. By using both bioassays and enzymatic assays, this study revealed long‐term noneffective and effective concentrations of imidacloprid that may be useful for accurate assessment of toxicity risk of neonicotinoids to bees.

Transcriptional Control of Honey Bee (Apis mellifera) Major Royal Jelly Proteins by 20-Hydroxyecdysone.

One of the first tasks of worker honey bees (Apis mellifera) during their lifetime is to feed the larval offspring. In brief, young workers (nurse bees) secrete a special food jelly that contains a large amount of unique major royal jelly proteins (MRJPs). The regulation of mrjp gene expression is not well understood, but the large upregulation in well-fed nurse bees suggests a tight repression until, or a massive induction upon, hatching of the adult worker bees. The lipoprotein vitellogenin, the synthesis of which is regulated by the two systemic hormones 20-hydroxyecdysone and juvenile hormone, is thought to be a precursor for the production of MRJPs. Thus, the regulation of mrjp expression by the said systemic hormones is likely. This study focusses on the role of 20-hydroxyecdysone by elucidating its effect on mrjp gene expression dynamics. Specifically, we tested whether 20-hydroxyecdysone displayed differential effects on various mrjps. We found that the expression of the mrjps (mrjp1–3) that were finally secreted in large amounts into the food jelly, in particular, were down regulated by 20-hydroxyecdysone treatment, with mrjp3 showing the highest repression value.

Measuring Hypopharyngeal Gland Acinus Size in Honey Bee (Apis mellifera) Workers.

The nurse hypopharyngeal glands produce the protein fraction of the worker and royal jelly that is fed to developing larvae and queens. These paired glands that are located in the head of the bee are highly sensitive to the quantity and quality of pollen and pollen substitutes that the nurse bee consumes. The glands get smaller when nurses are fed deficient diets and are large when they are fed complete diets. Because nurse hypopharyngeal gland size is a robust indicator of nurse nutrition, it is essential that those studying honey bee nutrition know how to measure these glands. Here, we provide detailed methods for dissecting, staining, imaging, and measuring nurse bee hypopharyngeal glands. We present comparisons of unstained and stained tissue and data that were used to study the impact of pollen on gland size. This method has been used to test how diet impacts hypopharyngeal gland size but has further use for understanding the role of these glands in hive health.

Quantifying the effects of pollen nutrition on honey bee queen egg laying with a new laboratory system.

Honey bee populations have been declining precipitously over the past decade, and multiple causative factors have been identified. Recent research indicates that these frequently co-occurring stressors interact, often in unpredictable ways, therefore it has become important to develop robust methods to assess their effects both in isolation and in combination. Most such efforts focus on honey bee workers, but the state of a colony also depends on the health and productivity of its queen. However, it is much more difficult to quantify the performance of queens relative to workers in the field, and there are no laboratory assays for queen performance. Here, we present a new system to monitor honey bee queen egg laying under laboratory conditions and report the results of experiments showing the effects of pollen nutrition on egg laying. These findings suggest that queen egg laying and worker physiology can be manipulated in this system through pollen nutrition, which is consistent with findings from field colonies. The results generated using this controlled, laboratory-based system suggest that worker physiology controls queen egg laying behavior. Additionally, the quantitative data generated in these experiments highlight the utility of the system for further use as a risk assessment tool.

The effects of raw propolis on Varroa-infested honey bee (Apis mellifera) workers.

Self-medication plays a major role in the behavioral defense against pathogens and parasites that animals have developed during evolution. The conditions defining this adaptive behavior are: (1) contact with the substance in question must be deliberate; (2) the substance must be detrimental to one or more parasites; (3) the detrimental effect on parasites must lead to increased host fitness. Recent studies have shown that A. mellifera colonies are able to increase resin foraging rates when infested by V. destructor, whereas further investigations are needed for evidence of parasite and host fitness. In order to understand whether Varroa-infested colonies could benefit from increasing levels of resin, we carried out laboratory bioassays to investigate the effects of propolis on the fitness of infested workers. The longevity and energetic stress of adult bees kept in experimental cages and artificially infested with the mite were thus monitored over time. At the same time, in vitro experiments were performed to study the contact effects of crude propolis on Varroa mites. Our results clearly demonstrate the positive effects of raw propolis on the lifespan of Varroa-infested adult bees. A low narcoleptic effect (19-22%) of raw propolis on phoretic mites after 5h was also observed. In terms of energetic stress, we found no differences between Varroa-free and Varroa-infested bees in terms of the daily sucrose solution demand. Our findings seem to confirm the hypothesis that resin collection and propolis use in the hive represent an example of self-medication behavior in social insects.

Olfactory associative behavioral differences in three honey bee Apis mellifera L. races under the arid zone ecosystem of central Saudi Arabia.

Apis mellifera jemenitica is the indigenous race of honey bees in the Arabian Peninsula and is tolerant to local drought conditions. Experiments were undertaken to determine the differences in associative learning and memory of honey bee workers living in the arid zone of Saudi Arabia, utilizing the proboscis extension response (PER). These experiments were conducted on the indigenous race (A. m. jemenitica) along with two introduced European races (A. m. carnica and A. m. ligustica). The data revealed that A. m. jemenitica is amenable to PER conditioning and may be used in conditioning experiments within the olfactory behavioral paradigm. The results also demonstrated that the three races learn and retain information with different capacities relative to each other during the experimental time periods. Native Arabian bees (A. m. jemenitica) exhibited significantly lower PER percentage during second and third conditioning trials when compared to exotic races. Apis mellifera jemenitica also exhibited reduced memory retention at 2 h and 24 h when compared to A. m. carnica and A. m. ligustica. Therefore, the native Arabian bees were relatively slow learners with reduced memory retention compared to the other two races that showed similar learning and memory retention. Three or five conditioning trials and monthly weather conditions (October and December) had no significant effects on learning and memory in A. m. jemenitica. These results emphasized a novel line of research to explore the mechanism and differences in associative learning as well as other forms of learning throughout the year among bee races in the harsh arid conditions of Saudi Arabia. This is the first study in Saudi Arabia to demonstrate inter-race differences regarding olfactory associative learning between native Arabian bees and two introduced European honey bee races.

Sesame Sesamum indicum L. (Pedaliaceae): Foraging Behavior of Honeybees Apis mellifera L. and Physicochemical Properties of Honey

A study of foraging behavior of honeybees, Apis mellifera L. on sesame, Sesamum indicum L. (Pedaliaceae) was conducted in Motobes district, Kafrelsheikh Province during July-August of 2016 and 2017. Also, the study aimed to ivestigate the foraging behavior of honeybees on sesame flowers and the physicochemical characteristics and mineral contents of sesame honey were determined. Sesame plants start to bloom in the 1st week of July and continues until the end of August during the two seasons. Workers of honeybees started to forage on sesame flowers after 0600 hrs, gradually increased until formed peak at 0900 and 1000 hrs, then gradually decreased and ceased at 1800 hrs. The maximum amounts of trapped sesame pollen/colony/hr were recorded at 0900 and1000 hrs. Sesame honey was characterized by high contents of fructose, glucose, maltose, K, Na, Ca, and P. It can be concluded that beekeepers can obtain good honey yield and/or trapped pollen loads from sesame during July and August. The component of sesame honey was found to be within the range of the required standards according to the international regulations of quality.

Length of stimulus presentation and visual angle are critical for efficient visual PER conditioning in the restrained honey bee, Apis mellifera.

Learning visual cues is an essential capability of bees for vital behaviors such as orientation in space and recognition of nest sites, food sources and mating partners. To study learning and memory in bees under controlled conditions, the proboscis extension response (PER) provides a well-established behavioral paradigm. While many studies have used the PER paradigm to test olfactory learning in bees because of its robustness and reproducibility, studies on PER conditioning of visual stimuli are rare. In this study, we designed a new setup to test the learning performance of restrained honey bees and the impact of several parameters: stimulus presentation length, stimulus size (i.e. visual angle) and ambient illumination. Intact honey bee workers could successfully discriminate between two monochromatic lights when the color stimulus was presented for 4, 7 and 10 s before a sugar reward was offered, reaching similar performance levels to those for olfactory conditioning. However, bees did not learn at shorter presentation durations. Similar to free-flying honey bees, harnessed bees were able to associate a visual stimulus with a reward at small visual angles (5deg) but failed to utilize the chromatic information to discriminate the learned stimulus from a novel color. Finally, ambient light had no effect on acquisition performance. We discuss possible reasons for the distinct differences between olfactory and visual PER conditioning.

Developmental changes in gene expression and enzyme activities of anabolic and catabolic enzymes for storage carbohydrates in the honeybee, Apis mellifera

Glycogen and trehalose are important sources of energy in insects. The expression of genes encoding the key metabolic enzymes—glycogen synthase (GS), glycogen phosphorylase (GP), trehalose-6-phosphate synthase (TPS-1), soluble trehalase (Tre-1) and membrane-bound trehalase (Tre-2)—was analyzed in 12 developmental stages of Apis mellifera worker brood. The content of GS and GP proteins, TPS activity, total trehalase activity, and the activity of Tre-1 and Tre-2 were determined. Transcript quantity was not always correlated with the content of the encoded GS or GP protein. The correlation was higher for GS (r = 0.797) than GP (r = 0.651). The expression of the glycogen synthase gene (gs) and the glycogen phosphorylase gene (gp) was high in 4- and 7-day-old larvae and in pupae, excluding the last pupal stage. The expression of the tps-1 gene was highest in the mid-pupal stage and contributed to higher enzyme activity in that stage. The expression of the tre-1 gene was higher than the expression of the tre-2 gene throughout development. In newly hatched workers, the expression of genes encoding catabolic enzymes of both carbohydrates, gp and tre-1, was higher than the expression of genes encoding anabolic enzymes. The results of this study suggest that sugar metabolism genes have somewhat different control mechanisms during larval development and metamorphosis.

Modulation of the honey bee queen microbiota: Effects of early social contact.

As the sole reproductive female in a honey bee (Apis mellifera) colony, the queen’s health is critical to colony productivity and longevity. Beekeeping operations typically rely on the commercial mass production of queens for colony multiplication, which involves manipulating and isolating the queens by confining them in cages during early development. Using common queen-rearing techniques, this study shows that segregating newly eclosed queens from their worker attendants for 72 hours using queen protector cages has a significant impact on the total amount of gut bacteria carried by those queens compared to queens that have unrestricted access to attendants upon eclosion. Isolated virgin queens sampled immediately after isolation at 4 days post eclosure had significantly more bacteria and a less consistent microbiota composition than their non-isolated peers. Furthermore, this effect lasted into the mating life of queens, since mated queens that had been isolated after emergence and then sampled at 14 days post eclosure also had significantly more microbiota compared to non-isolated mated queens of the same age. The causes and potential impacts of this alteration are not clear and deserve further investigation. This study also verifies earlier findings that honey bee queens lack the core microbiome found within honey bee workers.

Cryptic "royal" subfamilies in honey bee (Apis mellifera) colonies.

During emergency queen rearing, worker honey bees (Apis mellifera) select several otherwise worker-destined larvae to instead rear as candidates to replace their dead or failing queen. This choice is crucial as the queen is the sole reproductive in the colony and her quality is essential to its success. Because honey bee queens mate with and store sperm from multiple drones, emergency queen selection presents workers with an opportunity to increase fitness by selecting full- (0.75 relatedness), rather than half- (0.25 relatedness), sisters as new queen candidates. Through patriline analysis of colonies along with large numbers of emergency queens reared by each we affirm the purported “royal” patriline theory that, instead of competing nepotistically, workers exhibit bias towards selecting individuals from particular “royal” subfamilies during emergency queen rearing events, Further, we show that these “royal” patrilines are cryptic in honey bee colonies; occurring in such low frequency in the overall colony population that they are frequently undetected in traditional tests of queen mating number and colony composition. The identification of these cryptic “royal” subfamilies reveals that honey bee queens, already considered “hyperpolyandrous,” are mating with even more males than has been previously recognized. These results alter our understanding of reproductive behavior in honey bees, raising questions about the evolutionary implications of this phenomenon.

Experienced individuals influence the thermoregulatory fanning behaviour in honey bee colonies

The survival of an animal society depends on how individual interactions influence group coordination. Interactions within a group determine coordinated responses to environmental changes. Individuals that are especially influential affect the behavioural responses of other group members. This is exemplified by honey bee worker responses to increasing ambient temperatures by fanning their wings to circulate air through the hive. Groups of workers are more likely to fan than isolated workers, suggesting a coordinated group response. But are some individuals more influential than others in this response? This study tests the hypothesis that an individual influences other group members to perform thermoregulatory fanning behaviour in the western honey bee, Apis mellifera L. We show that groups of young nurse bees placed with fanners are more likely to initiate fanning compared to groups of nurses without fanners. Furthermore, we find that groups with young nurse bees have lower response thresholds than groups of just fanners. Our results suggest that individuals have the capability to influence other individuals to follow their fanning response as temperatures increase, and these social dynamics balance probability of fanning with thermal response thresholds. An influential individual may ultimately affect the ability for a society to efficiently respond to environmental fluctuations.

Epidemiological Survey of Ascosphaera apis in Small-Scale Migratory Apis mellifera iberiensis Colonies

Honey bee hives are moved yearly mainly for pollination, but also to take advantage of consecutive flowering events to get as many harvests of honey as possible and/or to find favorable sites for food sources and summer temperatures. Such movements may lead to pathogen spill-over with consequences on the honey bee health and finally on population decline. Ascosphaera apis is the causative agent of the chalkbrood disease, a pathology affecting honey bee larvae that significantly harms population growth and colony productivity. In this study, we detected the presence of A. apis in adult worker honey bees by PCR-amplification of the intergenic transcribed spacer (ITS1) of the ribosomal gene (rDNA). We first optimized the DNA extraction by testing different protocols in individual and pooled (colony level) adult honey bee samples. Subsequently, the presence of the fungus A. apis was assessed in both stationary and migratory colonies (subjected to small scale regional level movements) to determine the effect of migratory practices on the dispersal of this pathogen. Results confirmed a higher prevalence of A. apis in migratory apiaries when compared to stationary ones, indicating that migratory colonies are more likely to develop chalkbrood disease. Given these results, we suggest that beekeepers should be aware of the risks of pathogens spreading while moving beehives, even within a reduced geographic range.

Double-edged heat: honeybee participation in a hot defensive bee ball reduces life expectancy with an increased likelihood of engaging in future defense

Asian honeybees (Apis cerana) have evolved a thermal collective defense against the sympatric giant hornet (Vespa mandarinia) in which workers surround the predator en masse and produce heat up to 46 °C to kill it. This characteristic behavior is called “hot defensive bee ball formation.” Many studies have described the uniqueness and efficiency of this behavior; however, little attention has been paid to the potential cost to the honeybee. In this study, we focused on potential effects to bee ball-participating honeybees. We compared life expectancy of same-age ball-participating honeybees and nonparticipating honeybees and demonstrated that the life expectancy of the bee ball-participating honeybees was dramatically shortened. The 46 °C exposure also shortened the life expectancy of honeybees with induced expression of the heat shock protein gene, strongly implicating the increased temperature inside the bee ball in the deleterious effect on participating honeybees. We additionally found that bee ball-participating and then short-lived worker honeybees had a tendency to join a subsequent bee ball more aggressively. This tendency could mitigate accumulation of the short-lived worker honeybees within the colony, which otherwise would cause a severe reduction of honeybee colony activity. Social insects have evolved unique anti-predator altruistic behaviors for colony defense. Evaluation of the potential cost of these behaviors provides valuable insight into their evolution. Asian honeybees (Apis cerana) exhibit a sophisticated collective defense (bee ball formation) against the sympatric giant hornet (Vespa mandarinia) whose rigid exoskeleton resists the common stinging attack of the honeybees, utilizing heat. We found that the high temperature inside the ball itself dramatically reduced honeybee longevity. Furthermore, bee ball-experienced honeybees were found to be more likely to engage in subsequent bee ball formation. Our results pointed out unavoidable cost for the honeybee colony associated with the use of heat and a “division of risk” strategy in the bee colony for minimizing the cost.

Does the Pollen Diet Influence the Production and Expression of Antimicrobial Peptides in Individual Honey Bees?

We investigated the importance of protein nutrition for honey bee immunity. Different protein diets (monofloral pollen of Helianthus spp., Sinapis spp., Asparagus spp., Castanea spp., a mixture of the four different pollen and the pollen substitute FeedbeeTM) were fed to honey bees in cages ad libitum. After 18 days of feeding, apidaecin 1 isoforms concentration in the thorax were measured using nanoflow liquid chromatography coupled with mass spectrometry. Expression levels of genes, coding for apidaecins and abaecin in the abdomen were determined using quantitative PCR. The results indicate that protein-containing nutrition in adult worker honey bees can trigger certain metabolic responses. Bees without dietary protein showed lower apidaecin 1 isoforms concentrations. The significantly lowest concentration of apidaecin 1 isoforms was found in the group that was fed no pollen diet when compared to Asparagus, Castanea, Helianthus, and Sinapis pollen or the pollen supplement FeedBeeTM. Expression levels of the respective genes were also affected by the protein diets and different expression levels of these two antimicrobial peptides were found. Positive correlation between concentration and gene expression of apidaecins was found. The significance of feeding bees with different protein diets, as well as the importance of pollen nutrition for honey bee immunity is demonstrated.

Natural Honey Bee venom Manipulates Human Immune Response

Background: Honey bee venom is an important toxin which has various useful properties. Bee venom possesses various peptides including melittin, apamin, adolapamin and mast cell degranulating peptide. It appears to stimulate cortisone secretion, enhances antibody production, and affects cytokine production. Aim: The aim of the work is to study changes in levels of complement system proteins, C3 and C4, together with C-reactive proteins and rheumatoid factors (CRP and RF) in response to bee venom in subjects exposed naturally to sting with honey bee workers. Subjects and Methods: Subjects (12) were randomly selected from patients visiting El-Mostafa bee house, Elmarg, cairo, Egypt; to get natural bee venom therapy for various diseases. Blood samples (24) were collected from these volunteers, before and after honey bee sting, at the laboratory of Egypt Air Hospital, Cairo, Egypt following the standard protocol. Serum levels of C3 and C4 were measured by radial immunodiffusion technique. CRP was quantitatively measured by in vitro diagnostic test using auto analyzer (Dimension® EXEL) clinical chemistry system. Serum RF was measured by Rapid latex agglutination test for qualitative screening. Result: After exposure of patients to bee sting: all abnormal levels of C3 returned to normal values while abnormal C4 levels did not change; Half of cases that were showing abnormal high CRP levels have dropped to normal levels and All RF positive cases have become negative. Conclusion: The complement system has been activated, in patients, by both classical and alternative pathways before treatment with bee venom where it became only classically activated after treatment. Improved values of both CRP and RF indicate reduction in the inflammatory immune response after exposure of patients to honey bee venom.

Natural Honey Bee venom Manipulates Human Immune Response

Background: Honey bee venom is an important toxin which has various useful properties. Bee venom possesses various peptides including melittin, apamin, adolapamin and mast cell degranulating peptide. It appears to stimulate cortisone secretion, enhances antibody production, and affects cytokine production. Aim: The aim of the work is to study changes in levels of complement system proteins, C3 and C4, together with C-reactive proteins and rheumatoid factors (CRP and RF) in response to bee venom in subjects exposed naturally to sting with honey bee workers. Subjects and Methods: Subjects (12) were randomly selected from patients visiting El-Mostafa bee house, Elmarg, cairo, Egypt; to get natural bee venom therapy for various diseases. Blood samples (24) were collected from these volunteers, before and after honey bee sting, at the laboratory of Egypt Air Hospital, Cairo, Egypt following the standard protocol. Serum levels of C3 and C4 were measured by radial immunodiffusion technique. CRP was quantitatively measured by in vitro diagnostic test using auto analyzer (Dimension® EXEL) clinical chemistry system. Serum RF was measured by Rapid latex agglutination test for qualitative screening. Result: After exposure of patients to bee sting: all abnormal levels of C3 returned to normal values while abnormal C4 levels did not change; Half of cases that were showing abnormal high CRP levels have dropped to normal levels and All RF positive cases have become negative. Conclusion: The complement system has been activated, in patients, by both classical and alternative pathways before treatment with bee venom where it became only classically activated after treatment. Improved values of both CRP and RF indicate reduction in the inflammatory immune response after exposure of patients to honey bee venom.

Changes in Metabolic Activities and Gene Expression Associated with Gamma Irradiation of HoneybeeApis melliferaWorkers

ABSTRACT: This study was carried out to explore the possible stimulatory effect of a low dose of gamma irradiation on the expression profile of a number of genes and suspected metabolic mediators involved in honeybee (Apis mellifera) foraging activity. Honeybee workers were subjected to two gamma ray doses (0.2 and 2Gy) and the expression levels of Apis mellifera foraging gene (Amfor), juvenile hormone (JH), Octopamine receptor 1 (OctR1), heat shock protein- 70 (HSP- 70) and Troponin T (TpnT) mRNA levels were estimated using RT-PCR. In addition, the indicators of metabolic and flight rate changes such as citrate synthase (CS), pyruvate kinase (PK) and adenosine triphosphatase (ATPase) were estimated. The results revealed a marked increase in the expression of Amfor, JH, OctR1, HSP-70 and TpnT genes in the bees irradiated with the low dose of radiation (0.2Gy) as compared to the non-irradiated control workers and those irradiated with the higher dose (2Gy). In addition, CS, PK and ATPase activities were si...

Honeybee rebel workers invest less in risky foraging than normal workers

In eusocial insect colonies, workers have individual preferences for performing particular tasks. Previous research suggests that these preferences might be associated with worker reproductive potential; however, different studies have yielded inconsistent results. This study constitutes the first comparison of foraging preferences between genetically similar normal and rebel honeybee workers, which present different reproductive potential. We found that rebels, which have a higher reproductive potential than normal workers, displayed a delayed onset of foraging and a stronger tendency to collect nectar compared with normal workers. These results support the hypothesis that workers with high reproductive potential invest more in their own egg laying and avoid risky tasks such as foraging. In contrast, the results do not support the hypothesis that reproductive workers initiate foraging earlier in life than normal workers and specialize in pollen foraging.

The queen\u2019s gut refines with age: longevity phenotypes in a social insect model

BackgroundIn social insects, identical genotypes can show extreme lifespan variation providing a unique perspective on age-associated microbial succession. In honey bees, short- and long-lived host phenotypes are polarized by a suite of age-associated factors including hormones, nutrition, immune senescence, and oxidative stress. Similar to other model organisms, the aging gut microbiota of short-lived (worker) honey bees accrue Proteobacteria and are depleted of Lactobacillus and Bifidobacterium, consistent with a suite of host senescence markers. In contrast, long-lived (queen) honey bees maintain youthful cellular function with much lower expression of oxidative stress genes, suggesting a very different host environment for age-associated microbial succession.ResultsWe sequenced the microbiota of 63 honey bee queens exploring two chronological ages and four alimentary tract niches. To control for genetic and environmental variation, we quantified carbonyl accumulation in queen fat body tissue as a proxy for biological aging. We compared our results to the age-specific microbial succession of worker guts. Accounting for queen source variation, two or more bacterial species per niche differed significantly by queen age. Biological aging in queens was correlated with microbiota composition highlighting the relationship of microbiota with oxidative stress. Queens and workers shared many major gut bacterial species, but differ markedly in community structure and age succession. In stark contrast to aging workers, carbonyl accumulation in queens was significantly associated with increased Lactobacillus and Bifidobacterium and depletion of various Proteobacteria.ConclusionsWe present a model system linking changes in gut microbiota to diet and longevity, two of the most confounding variables in human microbiota research. The pattern of age-associated succession in the queen microbiota is largely the reverse of that demonstrated for workers. The guts of short-lived worker phenotypes are progressively dominated by three major Proteobacteria, but these same species were sparse or significantly depleted in long-lived queen phenotypes. More broadly, age-related changes in the honey bee microbiota reflect the regulatory anatomy of reproductive host metabolism. Our synthesis suggests that the evolution of colony-level reproductive physiology formed the context for host-microbial interactions and age-related succession of honey bee microbiota.