Honeybee Brain Research Articles

Differential Brain Expression Patterns of microRNAs Related to Olfactory Performance in Honey Bees (Apis mellifera).

MicroRNAs (miRNAs) play a vital role in the nerve regulation of honey bees (Apis mellifera). This study aims to investigate the differences in expression of miRNAs in a honey bee's brain for olfactory learning tasks and to explore their potential role in a honey bee's olfactory learning and memory. In this study, 12 day old honey bees with strong and weak olfactory performances were utilized to investigate the influence of miRNAs on olfactory learning behavior. The honey bee brains were dissected, and a small RNA-seq technique was used for high-throughput sequencing. The data analysis of the miRNA sequences revealed that 14 differentially expressed miRNAs (DEmiRNAs) between the two groups, strong (S) and weak (W), for olfactory performance in honey bees were identified, which included seven up-regulated and seven down-regulated. The qPCR verification results of the 14 miRNAs showed that four miRNAs (miR-184-3p, miR-276-3p, miR-87-3p, and miR-124-3p) were significantly associated with olfactory learning and memory. The target genes of these DEmiRNAs were subjected to the GO database annotation and KEGG pathway enrichment analyses. The functional annotation and pathway analysis showed that the neuroactive ligand-receptor interaction pathway, oxidative phosphorylation, biosynthesis of amino acids, pentose phosphate pathway, carbon metabolism, and terpenoid backbone biosynthesis may be a great important pathway related to olfactory learning and memory in honey bees. Our findings together further explained the relationship between olfactory performance and the brain function of honey bees at the molecular level and provides a basis for further study on miRNAs related to olfactory learning and memory in honey bees.

3D atlas of cerebral neuropils with previously unknown demarcations in the honey bee brain.

Honey bees (Apis mellifera) express remarkable social interactions and cognitive capabilities that have been studied extensively. In many cases, behavioral studies were accompanied by neurophysiological and neuroanatomical investigations. While most studies have focused on primary sensory neuropils, such as the optic lobes or antennal lobes, and major integration centers, such as the mushroom bodies or the central complex, many regions of the cerebrum (the central brain without the optic lobes) of the honey bee are only poorly explored so far, both anatomically and physiologically. To promote studies of these brain regions, we used anti-synapsin immunolabeling and neuronal tract tracings followed by confocal imaging and 3D reconstructions to demarcate all neuropils in the honey bee cerebrum and close this gap at the anatomical level. We demarcated 35 neuropils and 25 fiber tracts in the honey bee cerebrum, most of which have counterparts in the fly (Drosophila melanogaster) and other insect species that have been investigated so far at this level of detail. We discuss the role of cerebral neuropils in multisensory integration in the insect brain, emphasize the importance of this brain atlas for comparative studies, and highlight specific architectural features of the honey bee cerebrum.

Genome-wide analysis of the chromatin sites targeted by HEX 70a storage protein in the honeybee brain and fat body.

Hexamerins, the proteins massively stored in the larval haemolymph of insects, are gradually used throughout metamorphosis as a source of raw material and energy for the development of adult tissues. Such behaviour defined hexamerins as storage proteins. Immunofluorescence experiments coupled with confocal microscopy show a hexamerin, HEX 70a, in the nucleus of the brain and fat body cells from honeybee workers, an unexpected localization for a storage protein. HEX 70a colocalizes with fibrillarin, a nucleolar-specific protein and H3 histone, thus suggesting a potential role as a chromatin-binding protein. This was investigated through chromatin immunoprecipitation and high-throughput DNA sequencing (ChIP-seq). The significant HEX 70a-DNA binding sites were mainly localized at the intergenic, promoter and intronic regions. HEX 70a targeted DNA stretches mapped to the genomic regions encompassing genes with relevant functional attributes. Several HEX 70a targeted genes were associated with H3K27ac or/and H3K27me3, known as active and repressive histone marks. Brain and fat body tissues shared a fraction of the HEX 70 targeted genes, and tissue-specific targets were also detected. The presence of overrepresented DNA motifs in the binding sites is consistent with specific HEX 70a-chromatin association. In addition, a search for HEX 70a targets in RNA-seq public libraries of fat bodies from nurses and foragers revealed differentially expressed targets displaying hex 70a-correlated developmental expression, thus supporting a regulatory activity for HEX 70a. Our results support the premise that HEX 70a is a moonlighting protein that binds chromatin and has roles in the brain and fat body cell nuclei, apart from its canonical role as a storage protein.

Multisite imaging of neural activity using a genetically encoded calcium sensor in the honey bee.

Understanding of the neural bases for complex behaviors in Hymenoptera insect species has been limited by a lack of tools that allow measuring neuronal activity simultaneously in different brain regions. Here, we developed the first pan-neuronal genetic driver in a Hymenopteran model organism, the honey bee, and expressed the calcium indicator GCaMP6f under the control of the honey bee synapsin promoter. We show that GCaMP6f is widely expressed in the honey bee brain, allowing to record neural activity from multiple brain regions. To assess the power of this tool, we focused on the olfactory system, recording simultaneous responses from the antennal lobe, and from the more poorly investigated lateral horn (LH) and mushroom body (MB) calyces. Neural responses to 16 distinct odorants demonstrate that odorant quality (chemical structure) and quantity are faithfully encoded in the honey bee antennal lobe. In contrast, odor coding in the LH departs from this simple physico-chemical coding, supporting the role of this structure in coding the biological value of odorants. We further demonstrate robust neural responses to several bee pheromone odorants, key drivers of social behavior, in the LH. Combined, these brain recordings represent the first use of a neurogenetic tool for recording large-scale neural activity in a eusocial insect and will be of utility in assessing the neural underpinnings of olfactory and other sensory modalities and of social behaviors and cognitive abilities.

Mblk-1/E93, an ecdysone related-transcription factor, targets synaptic plasticity-related genes in the honey bee mushroom bodies.

Among hymenopteran insects, aculeate species such as bees, ants, and wasps have enlarged and morphologically elaborate mushroom bodies (MBs), a higher-order brain center in the insect, implying their relationship with the advanced behavioral traits of aculeate species. The molecular bases leading to the acquisition of complicated MB functions, however, remains unclear. We previously reported the constitutive and MB-preferential expression of an ecdysone-signaling related transcription factor, Mblk-1/E93, in the honey bee brain. Here, we searched for target genes of Mblk-1 in the worker honey bee MBs using chromatin immunoprecipitation sequence analyses and found that Mblk-1 targets several genes involved in synaptic plasticity, learning, and memory abilities. We also demonstrated that Mblk-1 expression is self-regulated via Mblk-1-binding sites, which are located upstream of Mblk-1. Furthermore, we showed that the number of the Mblk-1-binding motif located upstream of Mblk-1 homologs increased associated with evolution of hymenopteran insects. Our findings suggest that Mblk-1, which has been focused on as a developmental gene transiently induced by ecdysone, has acquired a novel expression pattern to play a role in synaptic plasticity in honey bee MBs, raising a possibility that molecular evolution of Mblk-1 may have partly contributed to the elaboration of MB function in insects.

Major royal jelly proteins influence the neurobiological regulation of the division of labor among honey bee workers

Age-based division of labor among workers is a fundamental life-history trait of many social insects, including the Western honey bee, Apis mellifera L. Extensive studies of the causation of the most pronounced transition from performing tasks in the nest to outside foraging indicate hormonal regulation of complex physiological changes. However, the proximate neurobiological mechanisms that cause the behavioral repertoire to change are still not understood and require novel approaches to be fully characterized. Thus, we established the first comprehensive monoclonal antibody microarray in honey bees with 16,320 antibodies to directly identify proteins in the brain that regulate the transition to foraging. Major royal jelly protein (MRJP) 1 and MRJP3 were identified as potential protein effectors and further investigated. A series of experimental manipulations of the workers' behavioral transition led to changes in MRJP1 and MRJP3 quantities in accordance with their presumed functional role. Injection of MRJPs into the brain resulted in increased task-reversal from foraging to nursing and decreased task-progression from nursing to foraging, while the latter was increased by injection with MRJP antibodies. Finally, down-regulation of MRJP1 and MRJP3 expression via RNAi injection into the brain increased the transition from in-hive nursing to outside foraging, confirming a causal role of these two proteins in the proximate regulation of behavior and life-history of honey bee workers. Interaction partners of MRJP1 and MRJP3 in the honey bee brain included other regulators of honey bee behavior and life history. Thus, our transformative methodological advancement of proteome analysis in honey bees reveals novel regulators of honey bee behavior, extends our understanding of the functional pleiotropy of MRJPs, and supports a general nutrition-based model of the regulation of the age-based division of labor in honey bees.

Chronic Cadmium Exposure Induces Impaired Olfactory Learning and Altered Brain Gene Expression in Honey Bees (Apis mellifera).

The honey bee (Apis mellifera) plays vital ecological roles in the pollination of crops and the maintenance of ecological balance, and adult honey bees may be exposed to exogenous chemicals including heavy metals during their foraging activities. Cadmium (Cd) is regarded as a nonessential toxic metal and is readily accumulated in plants; honey bees can therefore acquire Cd through the collection of contaminated nectar. In the present study, honey bees were chronically exposed to Cd to investigate the effects of sublethal cadmium doses on the olfactory learning and brain gene expression profiles of honey bees. The results showed that Cd-treated bees exhibited significantly impaired olfactory learning performances in comparison with control bees. Moreover, the head weight was significantly lower in Cd-treated bees than in control bees after chronic exposure to Cd. Gene expression profiles between the Cd treatment and the control revealed that 79 genes were significantly differentially expressed. Genes encoding chemoreceptors and olfactory proteins were downregulated, whereas genes involved in response to oxidative stress were upregulated in Cd-treated bees. The results suggest that Cd exposure exerts oxidative stress in the brain of honey bees, and the dysregulated expression of genes encoding chemoreceptors, olfactory proteins, and cytochrome P450 enzymes is probably associated with impaired olfactory learning in honey bees.

Inflammatory bowel disease-associated Escherichia coli strain LF82 in the damage of gut and cognition of honeybees.

Patients with inflammatory bowel disease (IBD) are often accompanied with some cognitive impairment, but the mechanism is unclear. By orally exposing honeybees (Apis mellifera) to IBD-associated Escherichia coli LF82 (LF82), and non-pathogenic Escherichia coli MG1655 (MG1655) as the normal strain, we investigated whether and how LF82 induces enteritis-like manifestations and cognitive behavioral modifications in honeybees using multiparametric analysis. LF82 significantly increased gut permeability, impaired learning and memory ability in olfactory proboscis extension response conditioning, and shortened the lifespan of honeybees. Compared to MG1655, LF82 reduced the levels of tryptophan metabolism pathway substances in the honeybee gut. LF82 also upregulated genes involved in immune and apoptosis-related pathways and downregulated genes involved in G protein-coupled receptors in the honeybee brain. In conclusion, LF82 can induce enteritis-like manifestations and cognition impairment through gut metabolites and brain transcriptome alteration in honeybees. Honeybees can serve as a novel potential model to study the microbiota-gut-brain interaction in IBD condition.

Immunohistochemical Distribution of Serotonin Transporter (SERT) in the Optic Lobe of the Honeybee, Apis mellifera.

Simple SummarySerotonin is ubiquitously expressed in vertebrates and invertebrates, where it regulates specific behavioural patterns. Though the specific effects of serotonin release in the optic lobe are not entirely known, increasing evidence associates the serotonergic system with optic lobe-mediated behaviours. In this study, the localization of serotonin transporter (SERT) was immunohistochemically analysed in the optic lobes of moderate, docile and aggressive worker honeybees. SERT-immunoreactive fibres were stratified in the optic lobe and distributed in the three visual neuropils: lamina, medulla and lobula. Interestingly, SERT immunoreactivity was inversely related to aggressive behaviour. The present study indicates that low levels of serotonin in the optic lobe are associated with aggressive behaviour.Visual information is processed in the optic lobes, which consist of three retinotopic neuropils. These are the lamina, the medulla and the lobula. Biogenic amines play a crucial role in the control of insect responsiveness, and serotonin is clearly related to aggressiveness in invertebrates. Previous studies suggest that serotonin modulates aggression-related behaviours, possibly via alterations in optic lobe activity. The aim of this investigation was to immunohistochemically localize the distribution of serotonin transporter (SERT) in the optic lobe of moderate, docile and aggressive worker honeybees. SERT-immunoreactive fibres showed a wide distribution in the lamina, medulla and lobula; interestingly, the highest percentage of SERT immunoreactivity was observed across all the visual neuropils of the docile group. Although future research is needed to determine the relationship between the distribution of serotonin fibres in the honeybee brain and aggressive behaviours, our immunohistochemical study provides an anatomical basis supporting the role of serotonin in aggressive behaviour in the honeybee.

Impairments in learning and memory performances associated with nicotinic receptor expression in the honeybee Apis mellifera after exposure to a sublethal dose of sulfoxaflor.

Sulfoxaflor is a new insecticide which acts on the nicotinic acetylcholine receptor (nAChRs) in a similar way to neonicotinoids. However, sufloxaflor (SFX) is thought to act in a different manner and is thus proposed as an alternative in crop protection. The goal of this study is to evaluate the toxicity of SFX and its sublethal effect on the honeybee Apis mellifera after acute exposure. In toxicological assay studies, the LD50 value and sublethal dose (corresponding to the NOEL: no observed effect level) were 96 and 15 ng/bee, respectively. Using the proboscis extension response paradigm, we found that an SFX dose of 15 ng/bee significantly impairs learning and memory retrieval when applied 12 h before conditioning or 24 h after olfactory conditioning. SFX had no effect on honeybee olfactory performance when exposure happened after the conditioning. Relative quantitative PCR experiments performed on the six nicotinic acetylcholine receptor subunits demonstrated that they are differently expressed in the honeybee brain after SFX exposure, whether before or after conditioning. We found that intoxicated bees with learning defects showed a strong expression of the Amelβ1 subunit. They displayed overexpression of Amelα9 and Amelβ2, and down-regulation of Amelα1, Amelα3 and Amelα7 subunits. These results demonstrated for the first time that a sublethal dose of SFX could affect honeybee learning and memory performance and modulate the expression of specific nAChR subunits in the brain.

Optimization of in vitro culture of honeybee nervous tissue for pesticide risk assessment

The most used pesticides have neurotoxic action on the neurotransmitter system of target and non-targeted insects, such as honeybees. However, honeybees have foremost importance worldwide, which has encouraged the development of tools to evaluate the action of specific pesticide molecules on their nervous system, providing accurate data on damage to their brain. In this sense, our study aimed to optimize in vitro honeybee nervous tissue culture to assess pesticide risks. To this end, six forager honeybee brains were dissected and transferred to different combinations of Leibovitz-15 (L-15) culture medium supplemented with Fetal Bovine Serum (FBS), Hank's Balanced Salt Solution (HBSS), and Insect Medium Supplement (IMS). Nervous tissues were collected after different incubation times (1, 6, 12, and 24 h) for morphology and Kenyon cell analyses. Our results showed that L-15 medium supplemented with HBSS and with HBSS plus FBS were the best media for culturing honey nervous tissue for 24 h, as they resulted in less tissue spacing and cell disarrangement. Therefore, they may be assessed in future ecotoxicological tests.

Proteome analysis reveals the molecular basis of honeybee brain and midgut response to sulfoxaflor

Sulfoxaflor is a widely used pesticide in agriculture. However, the molecular effects of sublethal sulfoxaflor on honeybees (Apis mellifera L.) remain elusive. Here, the effects of a sublethal dose of sulfoxaflor (0.05 μg/bee) on the brain and midgut proteome response of the honeybee were investigated. Exposure to sublethal sulfoxaflor doses did not cause significant honeybee death, but it induced significant alterations in the brain and midgut proteomes. After sulfoxaflor challenge, 135 and 28 proteins were differentially regulated in the brain and midgut, respectively. The up-regulated proteins were mainly implicated in energy metabolism, neurotransmitter transport and drug metabolism processes, and included in particular enzymes of the citrate cycle and cellular respiration process, such as ATP citrate synthase, malate dehydrogenase, cytochrome b-c1 complex subunits, and NADH dehydrogenase. These findings suggest that honeybees enhance energy metabolism in the midgut and brain to resist sulfoxaflor challenge. Notably, treatment with sulfoxaflor resulted in a 6.8 times increase in expression levels of the major royal jelly protein 1 (MRJP1) in the brain, and knockdown of MRJP1 mRNA expression using RNA interference significantly decreased the survival rate, indicating that MRJP1 may play an important role in sulfoxaflor tolerance. Our data reveals that sulfoxaflor influences multiple processes related to both metabolism and the nervous system, and provides novel insights into the molecular basis of the honeybee brain and midgut response to sublethal dose of sulfoxaflor.

Single-cell transcriptomic analysis of honeybee brains identifies vitellogenin as caste differentiation-related factor

SummaryThe honeybee (Apis mellifera) is a well-known eusocial insect. In honeybee colonies, thousands of sterile workers, including nurse and forager bees, perform various tasks within or outside the hive, respectively. The queen is the only fertile female and is responsible for reproduction. The queen and workers share similar genomes but occupy different caste statuses. We established single-cell transcriptomic atlases of brains from queens and worker subcastes and identified five major cell groups: Kenyon, optic lobe, olfactory projection, glial, and hemocyte cells. By dividing Kenyon and glial cells into multiple subtypes based on credible markers, we observed that vitellogenin (vg) was highly expressed in specific glial-cell subtypes in brains of queens. Knockdown of vg at the early larval stage significantly suppressed the development into adult queens. We demonstrate vg expression as a "molecular signature" for the queen caste and suggest involvement of vg in regulating caste differentiation.

In Search for the Retrievable Memory Trace in an Insect Brain

The search strategy for the memory trace and its semantics is exemplified for the case of olfactory learning in the honeybee brain. The logic of associative learning is used to guide the experimental approach into the brain by identifying the anatomical and functional convergence sites of the conditioned stimulus and unconditioned stimulus pathways. Two of the several convergence sites are examined in detail, the antennal lobe as the first-order sensory coding area, and the input region of the mushroom body as a higher order integration center. The memory trace is identified as the pattern of associative changes on the level of synapses. The synapses are recruited, drop out, and change the transmission properties for both specifically associated stimulus and the non-associated stimulus. Several rules extracted from behavioral studies are found to be mirrored in the patterns of synaptic change. The strengths and the weaknesses of the honeybee as a model for the search for the memory trace are addressed in a comparison with Drosophila. The question is discussed whether the memory trace exists as a hidden pattern of change if it is not retrieved and whether an external reading of the content of the memory trace may ever be possible. Doubts are raised on the basis that the retrieval circuits are part of the memory trace. The concept of a memory trace existing beyond retrieval is defended by referring to two well-documented processes also in the honeybee, memory consolidation during sleep, and transfer of memory across brain areas.

In-vivo egfp expression in the honeybee Apis mellifera induced by electroporation and viral expression vector.

In this study we describe egfp expression induced by two techniques: in vivo electroporation and viral transduction in several cell types of the adult honeybee brain. Non-neuronal and neuronal cell types were identified and the expression persisted at least during three days. Kenyon cells, optic lobe neurons and protocerebral lobe neurons were electroporated. Astrocyte-like glia cells, fibrous lamellar glia cells and cortex glia cells were identified. Viral transduction targeted one specific type of glia cells that could not be identified. EGFP positive cells types were rather variable after electroporation, and viral transduction resulted in more homogenous groups of positive cells. We propose that these techniques remain a good alternative to transgenic animals because they potentially target only somatic cells.

Food wanting is mediated by transient activation of dopaminergic signaling in the honey bee brain.

The biological bases of wanting have been characterized in mammals, but whether an equivalent wanting system exists in insects remains unknown. In this study, we focused on honey bees, which perform intensive foraging activities to satisfy colony needs, and sought to determine whether foragers leave the hive driven by specific expectations about reward and whether they recollect these expectations during their waggle dances. We monitored foraging and dance behavior and simultaneously quantified and interfered with biogenic amine signaling in the bee brain. We show that a dopamine-dependent wanting system is activated transiently in the bee brain by increased appetite and individual recollection of profitable food sources, both en route to the goal and during waggle dances. Our results show that insects share with mammals common neural mechanisms for encoding wanting of stimuli with positive hedonic value.

Numerosity Categorization by Parity in an Insect and Simple Neural Network

A frequent question as technology improves and becomes increasingly complex, is how we enable technological solutions and models inspired by biological systems. Creating technology based on humans is challenging and costly as human brains and cognition are complex. The honeybee has emerged as a valuable comparative model which exhibits some cognitive-like behaviors. The relative simplicity of the bee brain compared to large mammalian brains enables learning tasks, such as categorization, that can be mimicked by simple neural networks. Categorization of abstract concepts can be essential to how we understand complex information. Odd and even numerical processing is known as a parity task in human mathematical representations, but there appears to be a complete absence of research exploring parity processing in non-human animals. We show that free-flying honeybees can visually acquire the capacity to differentiate between odd and even quantities of 1–10 geometric elements and extrapolate this categorization to the novel numerosities of 11 and 12, revealing that such categorization is accessible to a comparatively simple system. We use this information to construct a neural network consisting of five neurons that can reliably categorize odd and even numerosities up to 40 elements. While the simple neural network is not directly based on the biology of the honeybee brain, it was created to determine if simple systems can replicate the parity categorization results we observed in honeybees. This study thus demonstrates that a task, previously only shown in humans, is accessible to a brain with a comparatively small numbers of neurons. We discuss the possible mechanisms or learning processes allowing bees to perform this categorization task, which range from numeric explanations, such as counting, to pairing elements and memorization of stimuli or patterns. The findings should encourage further testing of parity processing in a wider variety of animals to inform on its potential biological roots, evolutionary drivers, and potential technology innovations for concept processing.

Categorizing Visual Information in Subpopulations of Honeybee Mushroom Body Output Neurons.

Multisensory integration plays a central role in perception, as all behaviors usually require the input of different sensory signals. For instance, for a foraging honeybee the association of a food source includes the combination of olfactory and visual cues to be categorized as a flower. Moreover, homing after successful foraging using celestial cues and the panoramic scenery may be dominated by visual cues. Hence, dependent on the context, one modality might be leading and influence the processing of other modalities. To unravel the complex neural mechanisms behind this process we studied honeybee mushroom body output neurons (MBON). MBONs represent the first processing level after olfactory-visual convergence in the honeybee brain. This was physiologically confirmed in our previous study by characterizing a subpopulation of multisensory MBONs. These neurons categorize incoming sensory inputs into olfactory, visual, and olfactory-visual information. However, in addition to multisensory units a prominent population of MBONs was sensitive to visual cues only. Therefore, we asked which visual features might be represented at this high-order integration level. Using extracellular, multi-unit recordings in combination with visual and olfactory stimulation, we separated MBONs with multisensory responses from purely visually driven MBONs. Further analysis revealed, for the first time, that visually driven MBONs of both groups encode detailed aspects within this individual modality, such as light intensity and light identity. Moreover, we show that these features are separated by different MBON subpopulations, for example by extracting information about brightness and wavelength. Most interestingly, the latter MBON population was tuned to separate UV-light from other light stimuli, which were only poorly differentiated from each other. A third MBON subpopulation was neither tuned to brightness nor to wavelength and encoded the general presence of light. Taken together, our results support the view that the mushroom body, a high-order sensory integration, learning and memory center in the insect brain, categorizes sensory information by separating different behaviorally relevant aspects of the multisensory scenery and that these categories are channeled into distinct MBON subpopulations.

Transcriptomic analysis to elucidate the response of Apis mellifera ligustica brain tissue to fluvalinate exposure

As a commonly used acaricide in apiculture, fluvalinate is used to kill Varroa mites, while it also damages the nervous system of honeybees. To date, the transcriptomic characteristics associated with fluvalinate-induced neuronal injury in the bee brain have not been reported. Here, we performed transcriptome sequencing on Apis mellifera ligustica (A. mellifera ligustica) brain tissues collected before and after fluvalinate treatment. A total of 546 differentially expressed genes (DEGs) were detected, and these DEGs mainly showed 4 different expression patterns. Further analysis revealed that DEGs with different expression patterns were mainly involved in lipid metabolism, amino acid metabolism, visual transduction, and neural response-related GO terms and KEGG pathways. Moreover, protein–protein interaction network analysis revealed five protein-coding DEGs as key genes, which may play important roles in the resistance to fluvalinate-induced honeybee brain nerve tissue damage. In summary, this study is the first to perform a detailed characterization and functional analysis of genes related to fluvalinate stimulation in honeybee brains.

Context-dependent influence of threat on honey bee social network dynamics and brain gene expression.

Adverse social experience affects social structure by modifying the behavior of individuals, but the relationship between an individual's behavioral state and its response to adversity is poorly understood. We leveraged naturally occurring division of labor in honey bees and studied the biological embedding of environmental threat using laboratory assays and automated behavioral tracking of whole colonies. Guard bees showed low intrinsic levels of sociability compared with foragers and nurse bees, but large increases in sociability following exposure to a threat. Threat experience also modified the expression of caregiving-related genes in a brain region called the mushroom bodies. These results demonstrate that the biological embedding of environmental experience depends on an individual's societal role and, in turn, affects its future sociability.