Search

All organisms need to balance processes that consume energy against those that produce energy. With an increase in biological complexity over evolutionary time, regulation of this balance has become much more complex, resulting in specialization of metabolic tasks between organelles, cells, organs and, in the case of eusocial organisms, between the individuals that comprise the 'superorganism'. Exemplifying this, nurse honey bees maintain high abdominal lipids, while foragers have very low lipid stores, likely contributing to efficient performance of their social role, and thus to colony fitness. The proximate mechanisms responsible for these metabolic differences remain poorly understood. Here, we investigated the effects of age, worker class and dietary macronutrients on the abdominal activity of fatty acid synthase (FAS), the enzyme responsible for de novo synthesis of fatty acids, as well as the effects of age on lipase activity, enzymes responsible for the breakdown of stored lipids. We found that FAS but not lipase activity declines as bees age past peak nursing age. Feeding both nurses and foragers carbohydrates increased FAS activity compared with starved bees, but, whether fed or starved, nurses had much higher FAS activity than similarly treated foragers, implicating reduced lipid synthesis as one component of foragers' low lipid stores. Finally, we used artificial diets with different amounts of protein and fat to precociously induce low, forager-like FAS activity levels in nurse-age bees deprived of protein. We speculate that reduced protein appetite and consumption during the nurse-forager transition is responsible for suppressed lipid synthesis in foragers., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

Queen honey bees (Apis mellifera) release Queen Mandibular Pheromone (QMP) to regulate traits in the caste of female helpers called workers. QMP signals the queen's presence and suppresses worker reproduction. In the absence of reproduction, young workers take care of the queen and her larvae (nurse tasks), while older workers forage. In nurses, QMP increases lipid stores in abdominal fat tissue (fat body) and protein content in hypopharyngeal glands (HPG). HPG are worker-specific head glands that can synthesize proteinaceous jelly used in colony nourishment. Larger HPG signifies ability to secrete proteinaceous jelly, while shrunken glands characterize foragers that do not make jelly. While it is known that QMP increases abdominal lipid stores, the mechanism is unclear: Does QMP make workers consume more pollen which provides lipids, or does QMP increase lipogenic capacity? Here, we measure abdominal lipogenic capacity as fatty acid synthase (FAS) activity while monitoring abdominal protein content and HPG size in caged workers. Cages allow us to rigorously control worker age, pheromone exposure, and diet. In our 2-factorial design, 3- vs. 8-day-old workers (age factor) were exposed to synthetic QMP or not (pheromone factor) while consuming a lipid deficient diet. We found that QMP did not influence abdominal FAS activity or protein content, but QMP still increased HPG size in the absence of dietary lipids. Our data revealed a positive correlation between abdominal protein content and HPG size. Our findings show that QMP is not a strong modulator of lipogenic capacity in caged worker bees. However, our data may reflect that QMP mobilizes abdominal protein for production of jelly, in line with previous findings on effects of honey bee Brood Pheromone. Overall, our study expands the understanding of how QMP can affect honey bee workers. Such insights are important beyond regulatory biology, as QMP is used in various aspects of beekeeping., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Oreshkova et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

In many organisms, interactions among genes lead to multiple functional states, and changes to interactions can lead to transitions into new states. These transitions can be related to bifurcations (or critical points) in dynamical systems theory. Characterizing these collective transitions is a major challenge for systems biology. Here, we develop a statistical method for identifying bistability near a continuous transition directly from high-dimensional gene expression data. We apply the method to data from honey bees, where a known developmental transition occurs between bees performing tasks in the nest and leaving the nest to forage. Our method, which makes use of the expected shape of the distribution of gene expression levels near a transition, successfully identifies the emergence of bistability and links it to genes that are known to be involved in the behavioral transition. This proof of concept demonstrates that going beyond correlative analysis to infer the shape of gene expression distributions might be used more generally to identify collective transitions from gene expression data., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Daniels et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The protein vitellogenin (Vg) plays a central role in lipid transportation in most egg-laying animals. High Vg levels correlate with stress resistance and lifespan potential in honey bees (Apis mellifera). Vg is the primary circulating zinc-carrying protein in honey bees. Zinc is an essential metal ion in numerous biological processes, including the function and structure of many proteins. Measurements of Zn 2+ suggest a variable number of ions per Vg molecule in different animal species, but the molecular implications of zinc-binding by this protein are not well-understood. We used inductively coupled plasma mass spectrometry to determine that, on average, each honey bee Vg molecule binds 3 Zn 2+ -ions. Our full-length protein structure and sequence analysis revealed seven potential zinc-binding sites. These are located in the β-barrel and α-helical subdomains of the N-terminal domain, the lipid binding site, and the cysteine-rich C-terminal region of unknown function. Interestingly, two potential zinc-binding sites in the β-barrel can support a proposed role for this structure in DNA-binding. Overall, our findings suggest that honey bee Vg bind zinc at several functional regions, indicating that Zn 2+ -ions are important for many of the activities of this protein. In addition to being potentially relevant for other egg-laying species, these insights provide a platform for studies of metal ions in bee health, which is of global interest due to recent declines in pollinator numbers., (© 2022 The Authors. Insect Molecular Biology published by John Wiley & Sons Ltd on behalf of Royal Entomological Society.)

Proteins are under selection to maintain central functions and to accommodate needs that arise in ever-changing environments. The positive selection and neutral drift that preserve functions result in a diversity of protein variants. The amount of diversity differs between proteins: multifunctional or disease-related proteins tend to have fewer variants than proteins involved in some aspects of immunity. Our work focuses on the extensively studied protein Vitellogenin (Vg), which in honey bees (Apis mellifera) is multifunctional and highly expressed and plays roles in immunity. Yet, almost nothing is known about the natural variation in the coding sequences of this protein or how amino acid-altering variants might impact structure-function relationships. Here, we map out allelic variation in honey bee Vg using biological samples from 15 countries. The successful barcoded amplicon Nanopore sequencing of 543 bees revealed 121 protein variants, indicating a high level of diversity in Vg. We find that the distribution of non-synonymous single nucleotide polymorphisms (nsSNPs) differs between protein regions with different functions; domains involved in DNA and protein-protein interactions contain fewer nsSNPs than the protein's lipid binding cavities. We outline how the central functions of the protein can be maintained in different variants and how the variation pattern may inform about selection from pathogens and nutrition., (© 2022 The Authors. Protein Science published by Wiley Periodicals LLC on behalf of The Protein Society.)

Vitellogenin (Vg) is a phylogenetically broad glycolipophosphoprotein. A major function of this protein is holding lipid cargo for storage and transportation. Vg has been extensively studied in honey bees ( Apis mellifera ) due to additional functions in social traits. Using AlphaFold and EM contour mapping, we recently described the protein structure of honey bee Vg. The full-length protein structure reveals a large hydrophobic lipid binding site and a well-defined fold at the C-terminal region. Now, we outline a shielding mechanism that allows the C-terminal region of Vg to cover a large hydrophobic area exposed in the all-atom model. We propose that this C-terminal movement influences lipid molecules' uptake, transport, and delivery. The mechanism requires elasticity in the Vg lipid core as described for homologous proteins in the large lipid transfer protein (LLTP) superfamily to which Vg belongs. Honey bee Vg has, additionally, several structural arrangements that we interpret as beneficial for the functional flexibility of the C-terminal region. The mechanism proposed here may be relevant for the Vg molecules of many species., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Leipart, Halskau and Amdam.)

Vitellogenin (Vg) has been implicated as a central protein in the immunity of egg-laying animals. Studies on a diverse set of species suggest that Vg supports health and longevity through binding to pathogens. Specific studies of honey bees (Apis mellifera) further indicate that the vitellogenin (vg) gene undergoes selection driven by local pathogen pressures. Determining the complete 3D structure of full-length Vg (flVg) protein will provide insights regarding the structure-function relationships underlying allelic variation. Honey bee Vg has been described in terms of function, and two subdomains have been structurally described, while information about the other domains is lacking. Here, we present a structure prediction, restrained by experimental data, of flVg from honey bees. To achieve this, we performed homology modeling and used AlphaFold before using a negative-stain electron microscopy map to restrict, orient, and validate our 3D model. Our approach identified a highly conserved Ca 2+ -ion-binding site in a von Willebrand factor domain that might be central to Vg function. Thereafter, we used rigid-body fitting to predict the relative position of high-resolution domains in a flVg model. This mapping represents the first experimentally validated full-length protein model of a Vg protein and is thus relevant for understanding Vg in numerous species. Our results are also specifically relevant to honey bee health, which is a topic of global concern due to rapidly declining pollinator numbers., (© 2021 The Authors. FEBS Open Bio published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

Vitellogenin (Vg) is a conserved protein used by nearly all oviparous animals to produce eggs. It is also pleiotropic and performs functions in oxidative stress resistance, immunity, and, in honey bees, behavioral development of the worker caste. It has remained enigmatic how Vg affects multiple traits. Here, we asked whether Vg enters the nucleus and acts via DNA-binding. We used cell fractionation, immunohistology, and cell culture to show that a structural subunit of honey bee Vg translocates into cell nuclei. We then demonstrated Vg-DNA binding theoretically and empirically with prediction software and chromatin immunoprecipitation with sequencing (ChIP-seq), finding binding sites at genes influencing immunity and behavior. Finally, we investigated the immunological and enzymatic conditions affecting Vg cleavage and nuclear translocation and constructed a 3D structural model. Our data are the first to show Vg in the nucleus and suggest a new fundamental regulatory role for this ubiquitous protein., Supplementary Information: The online version contains supplementary material available at 10.1007/s13592-022-00914-9., Competing Interests: Conflict of interestThe authors declare no competing interests., (© The Author(s) 2022.)

Various bioactive food compounds may confer health and longevity benefits, possibly through altering or preserving the epigenome. While bioactive food compounds are widely being marketed for human consumption as 'improving health and longevity' by counteracting harmful effects of poor nutrition and lifestyle, claimed effects are often not adequately documented. Using the honey bee (Apis mellifera) as a model species, we here employed a multi-step screening approach to investigate seven compounds for effects on lifespan and DNA methylation using ELISA and whole genome bisulfite sequencing (WGBS). A positive longevity effect was detected for valproic acid, isovaleric acid, and cyanocobalamin. For curcumin, we found that lifespan shortening caused by ethanol intake, was restored when curcumin and ethanol were co-administered. Furthermore, we identified region specific DNA methylation changes as a result of ethanol intake. Ethanol specific changes in DNA methylation were fully or partially blocked in honey bees receiving ethanol and curcumin together. Ethanol-affected and curcumin-blocked differentially methylated regions covered genes involved in fertility, temperature regulation and tubulin transport. Our results demonstrate fundamental negative effects of low dose ethanol consumption on lifespan and associated DNA methylation changes and present a proof-of-principle on how longevity and DNA methylation changes can be negated by the bioactive food component curcumin. Our findings provide a fundament for further studies of curcumin in invertebrates., (© 2021. The Author(s).)

Human life expectancy increases, but the disease-free part of lifespan (healthspan) and the quality of life in old people may not show the same development. The situation poses considerable challenges to healthcare systems and economies, and calls for new strategies to increase healthspan and for sustainable future approaches to elder care. This call has motivated innovative research on the role of social relationships during ageing. Correlative data from clinical surveys indicate that social contact promotes healthy ageing, and it is time to reveal the causal mechanisms through experimental research. The fruit fly Drosophila melanogaster is a prolific model animal, but insects with more developed social behaviour can be equally instrumental for this research. Here, we discuss the role of social contact in ageing, and identify lines of study where diverse insect models can help uncover the mechanisms that are involved. This article is part of the theme issue 'Ageing and sociality: why, when and how does sociality change ageing patterns?'

Honey bees (Apis mellifera) provide an excellent model for studying how complex social behavior evolves and is regulated. Social behavioral traits such as the division of labor have been mapped to specific genomic regions in quantitative trait locus (QTL) studies. However, relating genomic mapping to gene function and regulatory mechanism remains a big challenge for geneticists. In honey bee workers, division of labor is known to be regulated by reproductive physiology, but the genetic basis of this regulation remains unknown. In this case, QTL studies have identified tyramine receptor 1 (TYR1) as a candidate gene in region pln2, which is associated with multiple worker social traits and reproductive anatomy. Tyramine (TA), a neurotransmitter, regulates physiology and behavior in diverse insect species including honey bees. Here, we examine directly the effects of TYR1 and TA on worker reproductive physiology, including ovariole number, ovary function and the production of vitellogenin (VG, an egg yolk precursor). First, we used a pharmacology approach to demonstrate that TA affects ovariole number during worker larval development and increases ovary maturation during the adult stage. Second, we used a gene knockdown approach to show that TYR1 regulates vg transcription in adult workers. Finally, we estimated correlations in gene expression and propose that TYR1 may regulate vg transcription by coordinating hormonal and nutritional signals. Taken together, our results suggest TYR1 and TA play important roles in regulating worker reproductive physiology, which in turn regulates social behavior. Our study exemplifies a successful forward-genetic strategy going from QTL mapping to gene function., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In animals, dietary restriction or suppression of genes involved in nutrient sensing tends to increase lifespan. In contrast, food restriction in honeybees ( Apis mellifera ) shortens lifespan by accelerating a behavioural maturation program that culminates in leaving the nest as a forager. Foraging is metabolically demanding and risky, and foragers experience increased rates of aging and mortality. Food-deprived worker bees forage at younger ages and are expected to live shorter lives. We tested whether suppression of a molecular nutrient sensing pathway is sufficient to accelerate the behavioural transition to foraging and shorten worker life. To achieve this, we reduced expression of the insulin receptor substrate ( irs ) gene via RNA interference in two selected lines of honeybees used to control for behavioural and genetic variation. irs encodes a membrane-associated protein in the insulin/insulin-like signalling (IIS) pathway that is central to nutrient sensing in animals. We measured foraging onset and lifespan and found that suppression of irs reduced worker bee lifespan in both genotypes, and that this effect was largely driven by an earlier onset of foraging behaviour in a genotype-conditional manner. Our results provide the first direct evidence that an IIS pathway gene influences behavioural maturation and lifespan in honeybees and highlight the importance of considering social environments and behaviours when investigating the regulation of aging and lifespan in social animals., Competing Interests: The authors declare no conflict of interest.

There is a growing need to understand relationships between agricultural intensification and global change. Monitoring solutions, however, often do not include pollinator communities that are of importance to ecosystem integrity. Here, we put forth the honey bee as an economical and broadly available bioindicator that can be used to assess and track changes in the quality of agricultural ecosystems. We detail a variety of simple, low-cost procedures that can be deployed within honey bee hives to gain generalizable information about ecosystem quality at multiple scales, and discuss the potential of the honey bee system in both environmental and ecological bioindication., (Copyright © 2019. Published by Elsevier Inc.)

Iron granules containing superparamagnetic magnetite act as magnetoreceptor for magnetoreception in honey bees. Biomineralization of iron granules occurs in the iron deposition vesicles of trophocytes and requires the participation of actin, myosin, ferritin2, and ATP synthase. The mechanism of magnetoreception in honey bees can be explored by suppressing the formation of iron granules. Toward this goal, we injected double-stranded RNA of ferritin2 and ferritin1 into newly emerged worker honey bees to knock down these genes via RNA interference. We confirmed that mRNA and protein production of the ferritins was inhibited, leading to immature iron granules. Downregulating ferritin2 and ferritin1, moreover, leads to different deposition morphology of 7.5-nm diameter iron particles, indicating that the two genes play different roles in the formation of iron granules in worker honey bees.

Insects have rapidly changing energy demands, so they primarily rely on hemolymph and other carbohydrates to carry out life activities. However, how gustatory responsiveness and hemolymph sugar levels coordinate with one another to maintain energetic homeostasis in insects remains largely unknown for the highly social honeybee that goes through large physiological and behavioral changes. The potential role of biogenic amines and neuropeptides in the connection between the regulation of appetite and fluctuating sugar levels in the hemolymph, due to starvation, as the bee ages, was investigated. The largest appetite increase due to the starvation treatment was within the forager age class and this corresponded with an increase in octopamine levels in the brain along with a decline in hemolymph sugar levels. Adipokinetic hormone (AKH) was found in very small quantities in the brain and there were no significant changes in response to starvation treatment. Our findings suggest that the particularly dynamic levels of hemolymph sugar levels may serve as a monitor of the forager honeybee energetic state. Therefore, there may be a pathway in forager bees via octopamine responsible for their precise precipitous regulation of appetite, but to determine cause and effect relationships further investigation is needed.

Foraging exposes organisms to rewarding and aversive events, providing a selective advantage for maximizing the former while minimizing the latter. Honey bees (Apis mellifera) associate environmental stimuli with appetitive or aversive experiences, forming preferences for scents, locations, and visual cues. Preference formation is influenced by inter-individual variation in sensitivity to rewarding and aversive stimuli, which can be modulated by pharmacological manipulation of biogenic amines. We propose that foraging experiences act on biogenic amine pathways to induce enduring changes to stimulus responsiveness. To simulate varied foraging conditions, freely-moving bees were housed in cages where feeders offered combinations of sucrose solution, floral scents, and aversive electric shock. Transient effects were excluded by providing bees with neutral conditions for three days prior to all subsequent assays. Sucrose responsiveness was reduced in bees that had foraged for scented rather than unscented sucrose under benign conditions. This was not the case under aversive foraging conditions, suggesting an adaptive tuning process which maximizes preference for high quality, non-aversive floral sites. Foraging conditions also influenced antennal lobe octopamine and serotonin, neuromodulators involved in stimulus responsiveness and foraging site evaluation. Our results suggest that individuals' foraging experiences durably modify neurochemistry and shape future foraging behaviour.

Heavy metal toxicity is an ecological concern in regions affected by processes like mining, industry, and agriculture. At sufficiently high concentrations, heavy metals are lethal to honey bees, but little is known about how sublethal doses affect honey bees or whether they will consume contaminated food. We investigated whether honey bees reject sucrose solutions contaminated with three heavy metals - cadmium, copper, and lead - as a measure of their ability to detect the metals, and whether ingesting these metals altered the bees' sucrose sensitivity. The metals elicited three different response profiles in honey bees. Cadmium was not rejected in any of the assays, and ingesting cadmium did not alter sucrose sensitivity. Copper was rejected following antennal stimulation, but was readily consumed following proboscis stimulation. Ingestion of copper did not alter sucrose sensitivity. Lead appeared to be palatable at some concentrations and altered the bees' sensitivity to and/or valuation of sucrose following antennal stimulation or ingestion of the metal. These differences likely represent unique mechanisms for detecting each metal and the pathology of toxicity. The bees' ability to detect and consume these toxic metals highlights the risk of exposure to these elements for bees living in or near contaminated environments.

Eusocial insects divide their labour so that individuals working inside the nest are affected by external conditions through a cascade of social interactions. Honey bees (Apis mellifera) transfer food and information via mouth-to-mouth social feeding, ie trophallaxis, a process known to be modulated by the rate of food flow at feeders and familiarity of food's scent. Little is understood about how aversive foraging conditions such as predation and con-specific competition affect trophallaxis. We hypothesized that aversive conditions have an impact on food transfer inside the colony. Here we explore the effect of foragers' aversive experience on downstream trophallaxis in a cage paradigm. Each cage contained one group of bees that was separated from feeders by mesh and allowed to feed only through trophallaxis, and another group that had access to feeders and self-specialized to either forage or distribute food. Our results show that aversive foraging conditions increase non-foragers' trophallaxis with bees restricted from feeder access when food is scented, and have the opposite effect when food is unscented. We discuss potential behavioural mechanisms and implications for the impact of aversive conditions such as malaise inducing toxins, predation, and con-specific competition.

The effect of larval nutrition on female fertility in honey bees is a focus for both scientific studies and for practical applications in beekeeping. In general, morphological traits are standards for classifying queens and workers and for evaluating their quality. In recent years, in vitro rearing techniques have been improved and used in many studies; they can produce queen-like and worker-like bees. Here, we questioned whether queens and workers reared in vitro are the same as queens and workers reared in a natural hive environment. We reared workers and queens both in vitro and naturally in beehives to test how these different environments affect metabolic physiology and candidate genes in newly emerged queens and workers. We found that sugar (glucose and trehalose) levels differed between queens and workers in both in vitro and in-hive-reared bees. The in vitro -reared bees had significantly higher levels of lipids in the abdomen. Moreover, hive reared queens had almost 20 times higher levels of vitellogenin than in vitro -reared queens, despite similar morphologies. In addition, hive-reared bees had significantly higher levels of expression of mrjp1 In conclusion, in vitro rearing produces queens and workers that differ from those reared in the hive environment at physiological and gene expression levels.This article has an associated First Person interview with the first author of the paper., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2018. Published by The Company of Biologists Ltd.)

Use of antibiotics in medicine and farming contributes to increasing numbers of antibiotic-resistant bacteria in diverse environments. The ability of antibiotic resistance genes (ARG) to transfer between bacteria genera contributes to this spread. It is difficult to directly link antibiotic exposure to the spread of ARG in a natural environment where environmental settings and study populations cannot be fully controlled. We used managed honeybees in environments with contrasting streptomycin exposure (USA: high exposure, Norway: low exposure) and mapped the prevalence and spread of transferrable streptomycin resistance genes. We found a high prevalence of strA-strB genes in the USA compared to Norway with 17/90 and 1/90 positive samples, respectively (p < 0.00007). We identified strA-strB genes on a transferrable transposon Tn5393 in the honeybee gut symbiont Snodgrassella alvi. Such transfer of resistance genes increases the risk of the spread to new environments as honeybees are moved to new pollination sites.

The honey bee has been extensively studied as a model for neuronal circuit and memory function and more recently has emerged as an unconventional model in biogerontology. Yet, the detailed knowledge of neuronal processing in the honey bee brain contrasts with the very sparse information available on glial cells. In other systems glial cells are involved in nutritional homeostasis, detoxification, and aging. These glial functions have been linked to metabolic enzymes, such as glutamine synthetase and glycogen phosphorylase. As a step in identifying functional roles and potential differences among honey bee glial types, we examined the spatial distribution of these enzymes and asked if enzyme abundance is associated with aging and other processes essential for survival. Using immunohistochemistry and confocal laser microscopy we demonstrate that glutamine synthetase and glycogen phosphorylase are abundant in glia but appear to co-localize with different glial sub-types. The overall spatial distribution of both enzymes was not homogenous and differed markedly between different neuropiles and also within each neuropil. Using semi-quantitative Western blotting we found that rapid aging, typically observed in shortest-lived worker bees (foragers), was associated with declining enzyme levels. Further, we found enzyme abundance changes after severe starvation stress, and that glutamine synthetase is associated with food response. Together, our data indicate that aging and nutritional physiology in bees are linked to glial specific metabolic enzymes. Enzyme specific localization patterns suggest a functional differentiation among identified glial types., Competing Interests: The authors have declared that no competing interests exist.

The gut microbiota of honeybees (Apis) and bumblebees (Bombus) include the symbiotic bacterial genus Gilliamella. This genus shows a high degree of functional and genomic diversity and separates into distinct lineages. Gilliamella apicola wkB1 T , which was isolated from Apis, was the first species to be described. Recently four new species, isolated from Bombus, were identified. In this paper, we compare several genomes/strains from previous studies spanning this diversity, which gives insight into the phylogenetic relationship among different Gilliamella species. We show that one lineage, isolated only from Apis, is different from other gilliamellas described, based on average nucleotide identity calculation (about 80 %) and phenotypic characterizations. We propose the new species name for this lineage: Gilliamella apis sp. nov. We present the characterization of the type strain NO3 T (=DSM 105629 T =LMG 30293 T ), a strain isolated from the Western honeybee Apis mellifera, which clusters within this lineage. Cells of strain NO3 T grow best in a microaerophilic atmosphere with enhanced CO2 levels at 36 °C and pH 7.0-7.5. Cells also grow well in anaerobic conditions, but not in aerobic conditions. Cells are approximately 1 µm in length and rod-shaped, and the genomic G+C content is 34.7 mol%. Differential characteristics between strain NO3 T and the different type strains of Gilliamella were revealed based on API kit tests and genomic content comparisons. The main respiratory quinone of strain NO3 T was ubiquinone-8, and the predominant fatty acids were C18 : 1ω7c/C18 : 1ω6c, C16 : 0, consistent with the genus Gilliamella.

Recent studies of honeybees and bumblebees have examined combinatory effects of different stressors, as insect pollinators are naturally exposed to multiple stressors. At the same time the potential influences of simultaneously occurring agricultural agents on insect pollinator health remain largely unknown. Due to different farming methods, and the drift of applied agents and manure, pollinators are most probably exposed to insecticides but also bacteria from organic fertilizers at the same time. We orally exposed honeybee workers to sub-lethal doses of the insecticide thiacloprid and two strains of the bacterium Enterococcus faecalis, which can occur in manure from farming animals. Our results show that under laboratory conditions the bees simultaneously exposed to the a bacterium and the pesticide thiacloprid thiacloprid had significant higher survival rates 11 days post exposure than the controls, which surprisingly showed the lowest survival. Bees that were exposed to diet containing thiacloprid showed decreased food intake. General antibacterial activity is increased by the insecticide and the bacteria, resulting in a higher immune response observed in treated individuals compared to control individuals. We thus propose that caloric restriction through behavioural and physiological adaptations may have mediated an improved survival and stress resistance in our tests. However, the decreased food consumption could in long-term also result in possible negative effects at colony level. Our study does not show an additive negative impact of sub-lethal insecticide and bacteria doses, when tested under laboratory conditions. In contrast, we report seemingly beneficial effects of simultaneous exposure of bees to agricultural agents, which might demonstrate a surprising biological capacity for coping with stressors, possibly through hormetic regulation.

There is little agreement among governments, institutions, scientists and food activists as to how to best tackle the challenging issues of health and sustainability in the food sector. This essay discusses the potential of school meals as a platform to promote healthy and sustainable food behavior. School meal programs are of particular interest for improving public diet because they reach children at a population scale across socio-economic classes and for over a decade of their lives, and because food habits of children are more malleable than those of adults. Current research on the history and health implications of school meal programs is reviewed in a cross-national comparative framework, and arguments explored that speak for the need of a new developmental phase of school meals as an integrative learning platform for healthy and sustainable food behavior. Nutritional, social, practical, educational, economical, political, and cultural perspectives and challenges linked to the implementation of healthy and sustainable school meals are discussed. Finally, the need for long-term interventions and evaluations is highlighted and new research directions are proposed.

How long-term antibiotic treatment affects host bacterial associations is still largely unknown. The honeybee-gut microbiota has a simple composition, so we used this gut community to investigate how long-term antibiotic treatment affects host-associated microbiota. We investigated the phylogenetic relatedness, genomic content (GC percentage, genome size, number of genes and CRISPR) and antibiotic-resistant genes (ARG) for strains from two abundant members of the honeybee core gut microbiota (Gilliamella apicola and Snodgrassella alvi). Domesticated honeybees are subjected to geographically different management policies, so we used two research apiaries, representing different antibiotic treatment regimens in their apiculture: low antibiotic usage (Norway) and high antibiotic usage (Arizona, USA). We applied whole-genome shotgun sequencing on 48 G. apicola and 22 S. alvi. We identified three predominating subgroups of G. apicola in honeybees from both Norway and Arizona. For G. apicola, genetic content substantially varied between subgroups and distance similarity calculations showed similarity discrepancy between subgroups. Functional differences between subgroups, such as pectin-degrading enzymes (G. apicola), were also identified. In addition, we identified horizontal gene transfer (HGT) of transposon (Tn10)-associated tetracycline resistance (Tet B) across the G. apicola subgroups in the Arizonan honeybees, using interspace polymorphisms in the Tet B determinant. Our results support that honeybee-gut symbiont subgroups can resist long-term antibiotic treatment and maintain functionality through acquisition of geographically distinct antibiotic-resistant genes by HGT., (© 2017 John Wiley & Sons Ltd.)

Honey bees as other insects rely on the innate immune system for protection against diseases. The innate immune system includes the circulating hemocytes (immune cells) that clear pathogens from hemolymph (blood) by phagocytosis, nodulation or encapsulation. Honey bee hemocyte numbers have been linked to hemolymph levels of vitellogenin. Vitellogenin is a multifunctional protein with immune-supportive functions identified in a range of species, including the honey bee. Hemocyte numbers can increase via mitosis, and this recruitment process can be important for immune system function and maintenance. Here, we tested if hemocyte mediated phagocytosis differs among the physiologically different honey bee worker castes (nurses, foragers and winter bees), and study possible interactions with vitellogenin and hemocyte recruitment. To this end, we adapted phagocytosis assays, which-together with confocal microscopy and flow cytometry-allow qualitative and quantitative assessment of hemocyte performance. We found that nurses are more efficient in phagocytic uptake than both foragers and winter bees. We detected vitellogenin within the hemocytes, and found that winter bees have the highest numbers of vitellogenin-positive hemocytes. Connections between phagocytosis, hemocyte-vitellogenin and mitosis were worker caste dependent. Our results demonstrate that the phagocytic performance of immune cells differs significantly between honey bee worker castes, and support increased immune competence in nurses as compared to forager bees. Our data, moreover, provides support for roles of vitellogenin in hemocyte activity.

Background: Diet and physical activity apps are two types of health apps that aim to promote healthy eating and energy expenditure through monitoring of dietary intake and physical activity. No clear evidence showing the effectiveness of using these apps to promote healthy eating and physical activity has been previously reported., Objective: This study aimed to identify how diet and physical activity (PA) apps affected their users. It also investigated if using apps was associated with changes in diet and PA., Methods: First, 3 semi-structured focus group discussions concerning app usability were conducted (15 app users and 8 nonusers; mean age 24.2 years, SD 6.4), including outcome measures such as motivations, experiences, opinions, and adherence. Results from the discussions were used to develop a questionnaire. The questionnaire, which contained questions about behavior changes, app usage, perceived effectiveness, and opinions of app usability, was answered by 500 Norwegians, with a mean age of 25.8 years (SD 5.1)., Results: App users found diet and PA apps effective in promoting healthy eating and exercising. These apps affected their actions, health consciousness, and self-education about nutrition and PA; and were also a part of their social lives. Over half of the users perceived that apps were effective in assisting them to eat healthily and to exercise more. Diet apps were more effective when they were frequently used and over a long period of time, compared to infrequent or short-term use (P=.01 and P=.02, respectively). Users who used diet and PA apps, perceived apps as more effective than users who only used one type of app (all P<.05). App users were better at maintaining diet and PA behaviors than nonusers (all P<.05). Young adults found apps fun to use, but sometimes time consuming. They wanted apps to be designed to meet their personal expectations., Conclusions: App usage influenced action, consciousness, self-education about nutrition and PA, and social life. It facilitated maintaining a healthy diet and exercising more. Diet and PA apps of the future can be further strengthened by being tailored to meet personal needs.

Environmental changes during development have long-term effects on adult phenotypes in diverse organisms. Some of the effects play important roles in helping organisms adapt to different environments, such as insect polymorphism. Others, especially those resulting from an adverse developmental environment, have a negative effect on adult health and fitness. However, recent studies have shown that those phenotypes influenced by early environmental adversity have adaptive value under certain (anticipatory) conditions that are similar to the developmental environment, though evidence is mostly from morphological and behavioral observations and it is still rare at physiological and molecular levels. In the companion study, we applied a short-term starvation treatment to fifth instar honey bee larvae and measured changes in adult morphology, starvation resistance, hormonal and metabolic physiology and gene expression. Our results suggest that honey bees can adaptively respond to the predicted nutritional stress. In the present study, we further hypothesized that developmental starvation specifically improves the metabolic response of adult bees to starvation instead of globally affecting metabolism under well-fed conditions. Here, we produced adult honey bees that had experienced a short-term larval starvation, then we starved them for 12 h and monitored metabolic rate, blood sugar concentrations and metabolic reserves. We found that the bees that experienced larval starvation were able to shift to other fuels faster and better maintain stable blood sugar levels during starvation. However, developmental nutritional stress did not change metabolic rates or blood sugar levels in adult bees under normal conditions. Overall, our study provides further evidence that early larval starvation specifically improves the metabolic responses to adult starvation in honey bees., (© 2016. Published by The Company of Biologists Ltd.)

Most organisms are constantly faced with environmental changes and stressors. In diverse organisms, there is an anticipatory mechanism during development that can program adult phenotypes. The adult phenotype would be adapted to the predicted environment that occurred during organism maturation. However, whether this anticipatory mechanism is present in eusocial species is questionable because eusocial organisms are largely shielded from exogenous conditions by their stable nest environment. In this study, we tested whether food deprivation during development of the honey bee (Apis mellifera), a eusocial insect model, can shift adult phenotypes to better cope with nutritional stress. After subjecting fifth instar worker larvae to short-term starvation, we measured nutrition-related morphology, starvation resistance, physiology, endocrinology and behavior in the adults. We found that the larval starvation caused adult honey bees to become more resilient toward starvation. Moreover, the adult bees were characterized by reduced ovary size, elevated glycogen stores and juvenile hormone (JH) titers, and decreased sugar sensitivity. These changes, in general, can help adult insects survive and reproduce in food-poor environments. Overall, we found for the first time support for an anticipatory mechanism in a eusocial species, the honey bee. Our results suggest that this mechanism may play a role in honey bee queen-worker differentiation and worker division of labor, both of which are related to the responses to nutritional stress., (© 2016. Published by The Company of Biologists Ltd.)

Well-known epigenetic DNA modifications in mammals include the addition of a methyl group and a hydroxyl group to cytosine, resulting in 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) respectively. In contrast, the abundance and the functional implications of these modifications in invertebrate model organisms such as the honey bee ( Apis mellifera ) and the fruit fly ( Drosophila melanogaster ) are not well understood. Here we show that both adult honey bees and fruit flies contain 5mC and also 5hmC. Using a highly sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) technique, we quantified 5mC and 5hmC in different tissues of adult honey bee worker castes and in adult fruit flies. A comparison of our data with reports from human and mouse shed light on notable differences in 5mC and 5hmC levels between tissues and species.

Objective: Consumers tend to have the perception that healthy equals less tasty. This study aimed to identify whether information provided by the Keyhole symbol, a widely used front-of-package symbol in Nordic countries to indicate nutritional content, and percent daily values (%DVs) affect Norwegian adolescents' perception of the healthiness of snacks and their intention to buy them., Design: Two tasks were used to evaluate adolescents' perception of snacks with the Keyhole symbol: with %DVs or with no nutrition label. A third task was used to test their abilities to use %DVs (pairwise selections). A survey obtained personal attributes., Participants: A total of 566 Norwegian adolescents., Main Outcome Measures: Taste perception, health perception, and ability to use %DVs., Analysis: Linear mixed models and logistic models that tested effects of labels and personal attributes on main outcome measures., Results: The Keyhole symbol increased health perception without influencing taste perception of snacks. Norwegian adolescents had limited abilities to use information from the %DVs correctly to identify healthier foods., Conclusions and Implications: Norwegian adolescents had a positive perception of the Keyhole symbols. Keyhole symbols as a simple, heuristic front-of-package label have potential as an information strategy that may influence self-efficacy in promoting healthy snack choices among adolescents., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

In comparative gerontology, highly social insects such as honey bees (Apis mellifera) receive much attention due to very different and flexible aging patterns among closely related siblings. While experimental strategies that manipulate socio-environmental factors suggest a causative link between aging and social signals and behaviors, the molecular underpinnings of this linkage are less well understood. Here we study the atypical localization of the egg-yolk protein vitellogenin (Vg) in the brain of the honey bee. Vg is known to influence honey bee social regulation and aging rate. Our findings suggest that Vg immunoreactivity in the brain is specifically localized within the class of non-neuronal glial cells. We discuss how these results can help explain the socially-dependent aging rate of honey bees., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Insect immune systems can recognize specific pathogens and prime offspring immunity. High specificity of immune priming can be achieved when insect females transfer immune elicitors into developing oocytes. The molecular mechanism behind this transfer has been a mystery. Here, we establish that the egg-yolk protein vitellogenin is the carrier of immune elicitors. Using the honey bee, Apis mellifera, model system, we demonstrate with microscopy and western blotting that vitellogenin binds to bacteria, both Paenibacillus larvae--the gram-positive bacterium causing American foulbrood disease--and to Escherichia coli that represents gram-negative bacteria. Next, we verify that vitellogenin binds to pathogen-associated molecular patterns; lipopolysaccharide, peptidoglycan and zymosan, using surface plasmon resonance. We document that vitellogenin is required for transport of cell-wall pieces of E. coli into eggs by imaging tissue sections. These experiments identify vitellogenin, which is distributed widely in oviparous species, as the carrier of immune-priming signals. This work reveals a molecular explanation for trans-generational immunity in insects and a previously undescribed role for vitellogenin.

Conventional invertebrate models of aging have provided striking examples for the influence of food- and nutrient-sensing on lifespan and stress resilience. On the other hand, studies in highly social insects, such as honey bees, have revealed how social context can shape very plastic life-history traits, for example flexible aging dynamics in the helper caste (workers). It is, however, not understood how food perception and stress resilience are connected in honey bee workers with different social task behaviors and aging dynamics. To explore this linkage, we tested if starvation resilience, which normally declines with age, depends on food responsiveness in honey bees. We studied two typically non-senesced groups of worker bees with different social task behaviors: mature nurses (caregivers) and mature foragers (food collectors). In addition, we included a group of old foragers for which functional senescence is well-established. Bees were individually scored for their food perception by measuring the gustatory response to different sucrose concentrations. Subsequently, individuals were tested for survival under starvation stress. We found that starvation stress resilience, but not gustatory responsiveness differed between workers with different social task behaviors (mature nurses vs. mature foragers). In addition starvation stress resilience differed between foragers with different aging progressions (mature foragers vs. old foragers). Control experiments confirmed that differences in starvation resilience between mature nurses and mature foragers were robust against changing experimental conditions, such as water provision and activity. For all worker groups we established that individuals with low gustatory responsiveness were more resilient to starvation stress. Finally, for the group of rapidly aging foragers we found that low food responsiveness was linked to a delayed age-related decline in starvation resilience. Our study highlights associations between reduced food perception, increased survival capacity and delayed aging in highly social honey bees. We discuss that these associations may involve canonical internal nutrient sensing pathways, which are shared between honey bees and animal models with less plastic aging dynamics., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats., Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits., Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation.

In vitro rearing is an important and useful tool for honey bee (Apis mellifera L.) studies. However, it often results in intercastes between queens and workers, which are normally are not seen in hive-reared bees, except when larvae older than three days are grafted for queen rearing. Morphological classification (queen versus worker or intercastes) of bees produced by this method can be subjective and generally depends on size differences. Here, we propose an alternative method for caste classification of female honey bees reared in vitro, based on weight at emergence, ovariole number, spermatheca size and size and shape, and features of the head, mandible and basitarsus. Morphological measurements were made with both traditional morphometric and geometric morphometrics techniques. The classifications were performed by principal component analysis, using naturally developed queens and workers as controls. First, the analysis included all the characters. Subsequently, a new analysis was made without the information about ovariole number and spermatheca size. Geometric morphometrics was less dependent on ovariole number and spermatheca information for caste and intercaste identification. This is useful, since acquiring information concerning these reproductive structures requires time-consuming dissection and they are not accessible when abdomens have been removed for molecular assays or in dried specimens. Additionally, geometric morphometrics divided intercastes into more discrete phenotype subsets. We conclude that morphometric geometrics are superior to traditional morphometrics techniques for identification and classification of honey bee castes and intermediates.

Lactobacillus kunkeei is a common inhabitant in honey bee gut, being present in several parts of the world. Here, we describe the draft genome of L. kunkeei AR114, an isolate from late foraging season in Norway., (Copyright © 2015 Porcellato et al.)

Variation in endocrine signaling is proposed to underlie the evolution and regulation of social life histories, but the genetic architecture of endocrine signaling is still poorly understood. An excellent example of a hormonally influenced set of social traits is found in the honey bee (Apis mellifera): a dynamic and mutually suppressive relationship between juvenile hormone (JH) and the yolk precursor protein vitellogenin (Vg) regulates behavioral maturation and foraging of workers. Several other traits cosegregate with these behavioral phenotypes, comprising the pollen hoarding syndrome (PHS) one of the best-described animal behavioral syndromes. Genotype differences in responsiveness of JH to Vg are a potential mechanistic basis for the PHS. Here, we reduced Vg expression via RNA interference in progeny from a backcross between 2 selected lines of honey bees that differ in JH responsiveness to Vg reduction and measured JH response and ovary size, which represents another key aspect of the PHS. Genetic mapping based on restriction site-associated DNA tag sequencing identified suggestive quantitative trait loci (QTL) for ovary size and JH responsiveness. We confirmed genetic effects on both traits near many QTL that had been identified previously for their effect on various PHS traits. Thus, our results support a role for endocrine control of complex traits at a genetic level. Furthermore, this first example of a genetic map of a hormonal response to gene knockdown in a social insect helps to refine the genetic understanding of complex behaviors and the physiology that may underlie behavioral control in general., (© The American Genetic Association. 2015.)

Background: Meiotic recombination has traditionally been explained based on the structural requirement to stabilize homologous chromosome pairs to ensure their proper meiotic segregation. Competing hypotheses seek to explain the emerging findings of significant heterogeneity in recombination rates within and between genomes, but intraspecific comparisons of genome-wide recombination patterns are rare. The honey bee (Apis mellifera) exhibits the highest rate of genomic recombination among multicellular animals with about five cross-over events per chromatid., Results: Here, we present a comparative analysis of recombination rates across eight genetic linkage maps of the honey bee genome to investigate which genomic sequence features are correlated with recombination rate and with its variation across the eight data sets, ranging in average marker spacing ranging from 1 Mbp to 120 kbp. Overall, we found that GC content explained best the variation in local recombination rate along chromosomes at the analyzed 100 kbp scale. In contrast, variation among the different maps was correlated to the abundance of microsatellites and several specific tri- and tetra-nucleotides., Conclusions: The combined evidence from eight medium-scale recombination maps of the honey bee genome suggests that recombination rate variation in this highly recombining genome might be due to the DNA configuration instead of distinct sequence motifs. However, more fine-scale analyses are needed. The empirical basis of eight differing genetic maps allowed for robust conclusions about the correlates of the local recombination rates and enabled the study of the relation between DNA features and variability in local recombination rates, which is particularly relevant in the honey bee genome with its exceptionally high recombination rate.

Epigenetic changes enable genomes to respond to changes in the environment, such as altered nutrition, activity, or social setting. Epigenetic modifications, thereby, provide a source of phenotypic plasticity in many species. The honey bee (Apis mellifera) uses nutritionally sensitive epigenetic control mechanisms in the development of the royal caste (queens) and the workers. The workers are functionally sterile females that can take on a range of distinct physiological and/or behavioral phenotypes in response to environmental changes. Honey bees have a wide repertoire of epigenetic mechanisms which, as in mammals, include cytosine methylation, hydroxymethylated cytosines, together with the enzymatic machinery responsible for these cytosine modifications. Current data suggests that honey bees provide an excellent system for studying the "social repertoire" of the epigenome. In this review, we elucidate what is known so far about the honey bee epigenome and its mechanisms. Our discussion includes what may distinguish honey bees from other model animals, how the epigenome can influence worker behavioral task separation, and how future studies can answer central questions about the role of the epigenome in social behavior.

Aim: Increased food consumption and the related problem of obesity have spurred initiatives to motivate consumers to eat healthier. Some strategies have shown positive but only short-term effects, as consumers or other stakeholders do not accept them sufficiently in the long term. The aim of this study was to investigate opportunities for healthier eating in Norway according to both consumers and other stakeholders., Methods: Five focus-group sessions were conducted with individuals working in the food industry, retail, public health, research and various non-governmental organisations related to food consumption. Topics that were discussed in the focus groups were transformed into a consumer survey, which was conducted with 1178 respondents., Results: The focus groups often indicated a specific responsibility for the food industry to get people to eat healthier. Survey respondents indicated that all actors in the food chain had responsibility for healthier eating in the population, but agreed that the food industry, as well as the health authority, have major responsibilities. Food education was regarded as a favourable strategy in the focus groups and by survey respondents to help people to eat healthier, as were less advertising of unhealthy food and developing new healthy food products. Such strategies should be focused on parents, families, schools and children according to both focus group and survey participants. Implementation challenges include consumers wanting freedom to choose what they eat and consumers wanting food information that is easier to understand., Conclusions: this study showed that consumers and other stakeholders see opportunities for healthier eating in Norway by providing more food education and clearer food information, targeted towards children, families and parents., (© 2014 the Nordic Societies of Public Health.)

The honey bee (Apis mellifera) is a domestic insect of high value to human societies, as a crop pollinator in agriculture and a model animal in scientific research. The honey bee, however, has experienced massive mortality worldwide due to the phenomenon Colony Collapse Disorder (CCD), resulting in alarming prospects for crop failure in Europe and the USA. The reasons for CCD are complex and much debated, but several honey bee pathogens are believed to be involved. Paratransgenesis is a Trojan horse strategy, where endogenous microorganisms are used to express effector molecules that antagonise pathogen development. For use in honey bees, paratransgenesis must rely on a set of criteria that the candidate paratransgenic microorganism must fulfil in order to obtain a successful outcome: (1) the candidate must be genetically modifiable to express effector molecules; (2) the modified organism should have no adverse effects on honey bee health upon reintroduction; and (3) it must survive together with other non-pathogenic bee-associated microorganisms. Lactic acid bacteria (LAB) are common gut bacteria in vertebrates and invertebrates, and some have naturally beneficial properties in their host. In the present work we aimed to find a potential paratransgenic candidate within this bacterial group for use in honey bees. Among isolated LAB associated with bee gut microbiota, we found the fructophilic Lactobacillus kunkeei to be the most predominant species during foraging seasons. Four genetically different strains of L. kunkeei were selected for further assessment. We demonstrated (1) that L. kunkeei is transformable; (2) that the transformed cells had no obvious adverse effect on honey bee survival; and (3) that transformed cells survived well in the gut environment of bees upon reintroduction. Our study demonstrates that L. kunkeei fulfils the three criteria for paratransgenesis and can be a suitable candidate for further research on this strategy in honey bees.

Honey bee workers display remarkable flexibility in the aging process. This plasticity is closely tied to behavioral maturation. Workers who initiate foraging behavior at earlier ages have shorter lifespans, and much of the variation in total lifespan can be explained by differences in pre-foraging lifespan. Vitellogenin (Vg), a yolk precursor protein, influences worker lifespan both as a regulator of behavioral maturation and through anti-oxidant and immune functions. Experimental reduction of Vg mRNA, and thus Vg protein levels, in wild-type bees results in precocious foraging behavior, decreased lifespan, and increased susceptibility to oxidative damage. We sought to separate the effects of Vg on lifespan due to behavioral maturation from those due to immune and antioxidant function using two selected strains of honey bees that differ in their phenotypic responsiveness to Vg gene knockdown. Surprisingly, we found that lifespans lengthen in the strain described as behaviorally and hormonally insensitive to Vg reduction. We then performed targeted gene expression analyses on genes hypothesized to mediate aging and lifespan: the insulin-like peptides (Ilp1 and 2) and manganese superoxide dismutase (mnSOD). The two honey bee Ilps are the most upstream components in the insulin-signaling pathway, which influences lifespan in Drosophila melanogaster and other organisms, while manganese superoxide dismutase encodes an enzyme with antioxidant functions in animals. We found expression differences in the llps in fat body related to behavior (llp1 and 2) and genetic background (Ilp2), but did not find strain by treatment effects. Expression of mnSOD was also affected by behavior and genetic background. Additionally, we observed a differential response to Vg knockdown in fat body expression of mnSOD, suggesting that antioxidant pathways may partially explain the strain-specific lifespan responses to Vg knockdown., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Honeybees show a remarkable behavioral plasticity at the transition from nursing inside the hive to foraging for nectar and/or pollen outside. This plasticity is important for age-related division of labor in honeybee colonies. The behavioral transition is associated with significant volume and synaptic changes in the mushroom bodies (MBs), brain centers for sensory integration, learning, and memory. We tested whether precocious sensory exposure to light leads to changes in the density of synaptic complexes [microglomeruli (MG)] in the MBs. The results show that exposure to light pulses over 3 days induces a significant decrease in the MG density in visual subregions (collar) of the MB. Earlier studies had shown that foragers have increased levels of juvenile hormone (JH) co-occurring with a decrease of vitellogenin (Vg). Previous work further established that RNAi-mediated knockdown of vg and ultraspiracle (usp) induced an upregulation of JH levels, which can lead to precocious foraging. By disturbing both Vg and JH pathways using gene knockdown of vg and usp, we tested whether the changes in the hormonal system directly affect MG densities. Our study shows that MG numbers remained unchanged when Vg and JH pathways were perturbed, suggesting no direct hormonal influences on MG densities. However, mass spectrometry detection of JH revealed that precocious light exposure triggered an increase in JH levels in the hemolymph (HL) of young bees. This suggests a dual effect following light exposure via direct effects on MG reorganization in the MB calyx and a possible positive feedback on HL JH levels., (© 2014 Wiley Periodicals, Inc.)

The rise in metabolic disorders in the past decades has heightened focus on achieving a healthy dietary balance in humans. This is also an increasingly important issue in the management of honey bees (Apis mellifera) where poor nutrition has negative effects on health and productivity in agriculture, and nutrition is suggested as a contributing factor in the recent global declines in honey bee populations. As in other organisms, the insulin/insulin-like signaling (IIS) pathway is likely involved in maintaining nutrient homeostasis in honey bees. Honey bees have two insulin-like peptides (Ilps) with differing spatial expression patterns in the fat body suggesting that AmIlp1 potentially functions in lipid metabolism while AmIlp2 is a more general indicator of nutritional status. We fed caged worker bees artificial diets high in carbohydrates, proteins or lipids and measured expression of AmIlp1, AmIlp2, and the insulin receptor substrate (IRS) to test their responses to dietary macronutrients. We also measured lifespan, worker weight and gustatory sensitivity to sugar as measures of individual physical condition. We found that expression of AmIlp1 was affected by diet composition and was highest on a diet high in protein. Expression of AmIlp2 and AmIRS were not affected by diet. Workers lived longest on a diet high in carbohydrates and low in protein and lipids. However, bees fed this diet weighed less than those that received a diet high in protein and low in carbohydrates and lipids. Bees fed the high carbohydrates diet were also more responsive to sugar, potentially indicating greater levels of hunger. These results support a role for AmIlp1 in nutritional homeostasis and provide new insight into how unbalanced diets impact individual honey bee health., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

This paper is based on a workshop held in Oslo, Norway in November 2013, in which experts discussed how to reach consensus on the healthiness of red and processed meat. Recent nutritional recommendations include reducing intake of red and processed meat to reduce cancer risk, in particular colorectal cancer (CRC). Epidemiological and mechanistic data on associations between red and processed meat intake and CRC are inconsistent and underlying mechanisms are unclear. There is a need for further studies on differences between white and red meat, between processed and whole red meat and between different types of processed meats, as potential health risks may not be the same for all products. Better biomarkers of meat intake and of cancer occurrence and updated food composition databases are required for future studies. Modifying meat composition via animal feeding and breeding, improving meat processing by alternative methods such as adding phytochemicals and improving our diets in general are strategies that need to be followed up., (Copyright © 2014. Published by Elsevier Ltd.)

The honey bee is a well-established model organism to study aging, learning and memory. Here, we used young and old forager honey bees to investigate whether age-related learning capacity correlates with mitochondrial function. The bees were selected for age and learning performance and mitochondrial function was evaluated by measuring mtDNA integrity, mtDNA copy number and mitochondrial gene expression. Quite unexpectedly, mtDNA from young bees showed more damage than mtDNA from older bees, but neither mtDNA integrity, nor mtDNA copy number nor mitochondrial gene expression correlated with learning performance. Although not statistically significant (p=0.07) the level of L-rRNA increased with age in good learners whereas it decreased in poor learners. Our results show that learning performance in honey bee does not correlate with absolute mitochondrial parameters like mtDNA damage, copy number or expression of mitochondrial genes, but may be associated with the ability to regulate mitochondrial activity., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The food a honey bee female larva receives determines whether she develops into a large long-lived fertile queen or a short-lived sterile worker. Through well-established nutrient-sensing and growth-promoting functions in metazoans, the insulin/insulin-like growth factor 1 signaling (IIS) pathway has become a focal topic in investigations on how differences in food environment can be translated into internal signals responsible for queen-worker determination. However, low expression levels of two insulin receptors (AmInRs) in honey bee larvae and the failure of one AmInR to influence caste differentiation are in potential conflict with such a classical growth-promoting role of IIS in queen-worker development. In view of such an apparent contradiction, and the fact that binding partners and affinities of these two AmInRs have not been worked out, we performed a functional study on insulin-like peptide genes (AmILP1 and AmILP2) in honey bee larvae by using a double-stranded RNA (dsRNA)-mediated gene knockdown approach. We found that juvenile hormone (JH) levels were diminished by AmILP1 dsRNA treatment, while the AmILP2 knockdown caused a reduction in ovary size. Blood sugar titers were not significantly affected by the treatments. From these results we conclude that AmILP2 transcript levels may influence specific organ development, such as the ovary and body mass, while more general traits of caste differentiation, such as mandibles, may require additional regulators. In addition, JH production may be regulated by AmILP1 expressed locally in the brain, similar to the function of certain ILPs in Drosophila.

In honey bees, vitellogenin (Vg) is hypothesized to be a major factor affecting hormone signaling, food-related behavior, immunity, stress resistance and lifespan. MicroRNAs, which play important roles in post-transcriptional gene regulation, likewise affect many biological processes. The actions of microRNAs and Vg are known to intersect in the context of reproduction; however, the role of these associations on social behavior is unknown. The phenotypic effects of Vg knockdown are best established and studied in the forager stage of workers. Thus, we exploited the well-established RNA interference (RNAi) protocol for Vg knockdown to investigate its downstream effects on microRNA population in honey bee foragers' brain and fat body tissue. To identify microRNAs that are differentially expressed between tissues in control and knockdown foragers, we used μParaflo microfluidic oligonucleotide microRNA microarrays. Our results showed that 76 and 74 microRNAs were expressed in the brain of control and knockdown foragers whereas 66 and 69 microRNAs were expressed in the fat body of control and knockdown foragers, respectively. Target prediction identified potential seed matches for a differentially expressed subset of microRNAs affected by Vg knockdown. These candidate genes are involved in a broad range of biological processes including insulin signaling, juvenile hormone (JH) and ecdysteroid signaling previously shown to affect foraging behavior. Thus, here we demonstrate a causal link between the Vg knockdown forager phenotype and variation in the abundance of microRNAs in different tissues, with possible consequences for the regulation of foraging behavior.