A preliminary survey reveals that common viruses are found at low titers in a wild population of honey bees (Apis mellifera).

A major threat to honey bee (Apis mellifera Linnaeus, Hymenoptera: Apidae) health continues to be parasitism by the mite Varroa destructor, which has been linked to high colony losses worldwide. Besides feeding on developing and adult bees, Varroa is also a prolific vector of honey bee-associated viruses. Because they live in unmanaged conditions, wild honey bee colonies are not treated against Varroa, which has enabled the natural selection of more mite-tolerant bees. To date, few studies have explored the prevalence of viruses in unmanaged colonies. The Welder Wildlife Refuge (WWR) in Texas is a unique site to study the viral landscape of unmanaged honey bees in the United States. The goals of this study were to identify and quantify viruses in wild colonies at the WWR, to examine changes in the prevalence of viruses in these colonies over time, and to compare the presence and titers of viruses between wild colonies at the WWR and those from the nearest managed apiary. We collected bees from colonies at the WWR in 2013, 2016, and 2021, and analyzed selected viruses for their presence and titers via quantitative polymerase chain reaction. In 2021, we also sampled bees from the nearest managed apiary for comparison. We found low average virus titers in all wild colonies sampled, and no difference in virus titers between colonies at the WWR and those from the managed apiary. Our study indicates that virus titers in wild colonies at the WWR are similar to those found in nearby colonies, and that these titers fluctuate over time.

Beyond conflict: Kinship theory of intragenomic conflict predicts individual variation in altruistic behaviour.

Behavioural variation is essential for animals to adapt to different social and environmental conditions. The Kinship Theory of Intragenomic Conflict (KTIC) predicts that parent-specific alleles can support different behavioural strategies to maximize allele fitness. Previous studies, including in honey bees (Apis mellifera), supported predictions of the KTIC for parent-specific alleles to promote selfish behaviour. Here, we test the KTIC prediction that for altruism-promoting genes (i.e. those that promote behaviours that support the reproductive fitness of kin), the allele with the higher altruism optimum should be selected to be expressed while the other is silenced. In honey bee colonies, workers act altruistically when tending to the queen by performing a 'retinue' behaviour, distributing the queen's mandibular pheromone (QMP) throughout the hive. Workers exposed to QMP do not activate their ovaries, ensuring they care for the queen's brood instead of competing to lay unfertilized eggs. Due to the haplodiploid genetics of honey bees, the KTIC predicts that response to QMP is favoured by the maternal genome. We report evidence for parent-of-origin effects on the retinue response behaviour, ovarian development and gene expression in brains of worker honey bees exposed to QMP, consistent with the KTIC. Additionally, we show enrichment for genes with parent-of-origin expression bias within gene regulatory networks associated with variation in bees' response to QMP. Our study demonstrates that intragenomic conflict can shape diverse social behaviours and influence expression patterns of single genes as well as gene networks.

Examining parent-of-origin effects on transcription and RNA methylation in mediating aggressive behavior in honey bees (Apis mellifera).

Conflict between genes inherited from the mother (matrigenes) and the father (patrigenes) is predicted to arise during social interactions among offspring if these genes are not evenly distributed among offspring genotypes. This intragenomic conflict drives parent-specific transcription patterns in offspring resulting from parent-specific epigenetic modifications. Previous tests of the kinship theory of intragenomic conflict in honey bees (Apis mellifera) provided evidence in support of theoretical predictions for variation in worker reproduction, which is associated with extreme variation in morphology and behavior. However, more subtle behaviors - such as aggression - have not been extensively studied. Additionally, the canonical epigenetic mark (DNA methylation) associated with parent-specific transcription in plant and mammalian model species does not appear to play the same role as in honey bees, and thus the molecular mechanisms underlying intragenomic conflict in this species is an open area of investigation. Here, we examined the role of intragenomic conflict in shaping aggression in honey bee workers through a reciprocal cross design and Oxford Nanopore direct RNA sequencing. We attempted to probe the underlying regulatory basis of this conflict through analyses of parent-specific RNA m6A and alternative splicing patterns. We report evidence that intragenomic conflict occurs in the context of honey bee aggression, with increased paternal and maternal allele-biased transcription in aggressive compared to non-aggressive bees, and higher paternal allele-biased transcription overall. However, we found no evidence to suggest that RNA m6A or alternative splicing mediate intragenomic conflict in this species.

The microbiome and gene expression of honey bee workers are affected by a diet containing pollen substitutes.

Pollen is the primary source of dietary protein for honey bees. It also includes complex polysaccharides in its outer coat, which are largely indigestible by bees but can be metabolized by bacterial species within the gut microbiota. During periods of reduced availability of floral pollen, supplemental protein sources are frequently provided to managed honey bee colonies. The crude proteins in these supplemental feeds are typically byproducts from food manufacturing processes and are rarely derived from pollen. Our experiments on the impact of different diets showed that a simplified pollen-free diet formulated to resemble the macronutrient profile of a monofloral pollen source resulted in larger microbial communities with reduced diversity, reduced evenness, and reduced levels of potentially beneficial hive-associated bacteria. Furthermore, the pollen-free diet sharply reduced the expression of genes central to honey bee development. In subsequent experiments, we showed that these shifts in gene expression may be linked to colonization by the gut microbiome. Lastly, we demonstrated that for bees inoculated with a defined gut microbiota, those raised on an artificial diet were less able to suppress infection from a bacterial pathogen than those that were fed natural pollen. Our findings demonstrate that a pollen-free diet significantly impacts the gut microbiota and gene expression of honey bees, indicating the importance of natural pollen as a primary protein source.

Transcriptomic analysis of the honey bee (Apis mellifera) queen brain reveals that gene expression is affected by pesticide exposure during development.

Honey bees (Apis mellifera) play a pivotal role in agricultural production worldwide, primarily through the provision of pollination services. But despite their importance, honey bee health continues to be threatened by many factors, including parasitization by the mite Varroa destructor, poor queen quality, and pesticide exposure. Accumulation of pesticides in the hive's comb matrix over time inevitably leads to the exposure of developing brood, including queens, to wax contaminated with multiple compounds. Here, we characterized the brain transcriptome of queens that were reared in wax contaminated with pesticides commonly found in commercial beekeeping operations including either (a) a combination of 204,000 ppb of tau-fluvalinate and 91,900 ppb of coumaphos ("FC" group), (b) a combination of 9,800 ppb of chlorpyrifos and 53,700 ppb of chlorothalonil ("CC" group), or (c) 43,000 ppb of amitraz ("A" group). Control queens were reared in pesticide-free wax. Adult queens were allowed to mate naturally before being dissected. RNA isolated from brain tissue from three individuals per treatment group was sequenced using three technical replicates per queen. Using a cutoff log2 fold-change value of 1.5, we identified 247 differentially expressed genes (DEGs) in the FC group, 244 in the CC treatment group, and 668 in the A group, when comparing each group to the control. This is the first study to examine the sublethal effects of pesticides commonly found in wax (particularly amitraz) on the queen's brain transcriptome. Future studies should further explore the relationship between our molecular findings and the queen's behavior and physiology.

Prognostic factors for brain metastasis in women presenting cervical cancer.

PURPOSE: Although rare, brain metastases (BM) from cervical cancer (CC) are highly lethal. Adequate patient selection for specific treatments can improve survival rates in patients afflicted by this condition. This study aimed to describe the characteristics of CC patients who developed BM and overall survival-associated factors. Brain metastasis impact on the overall survival was assessed as a secondary objective. METHODS: This assessment comprises a retrospective cohort study on 3394 women presenting CC diagnosed between January 2010 and December 2017 at a single referral center. Incident BM cases were included. Descriptive statistics were calculated. Kaplan-Meier curves were used for the survival analysis and a Cox proportional hazards regression model was applied to explore the risk of death according to the analyzed independent variables. RESULTS: A total of 48 incident BM cases were identified. The median time between CC diagnosis and BM development was 1.5 years. Headaches (29.2%), dizziness/altered balance (29.2%), vertigo (29.2%) and motor disturbances (25.0%) were the most common signs and symptoms at presentation. Median overall survival after BM diagnosis was of 1.6 months (95% CI 0.9-2.3) while in the group of women without BM it was 5.5 years (95% CI 4.9-6.1). Concerning the Cox multivariate analysis, presenting one extracerebral metastases site (HR 2.8; 95% CI 1.3-6.2; p = 0.009) and receiving supportive treatment (HR 13.7; 95% CI 3.1-60.5; p 0.001) were independently associated with the risk of death. CONCLUSION: The median survival of women with BM following CC was poor. Women without extracerebral metastases and undergoing multimodal treatment displayed better overall survival rates.

Incidence and risk factors associated with the development of metastatic spinal cord compression due to bone metastasis in women with cervical cancer.

PURPOSE: The aim of this study was to determine the incidence and factors associated with the development of metastatic spinal cord compression (MSCC) after cervical cancer (CC). METHODS: This retrospective cohort of 3551 women with CC who underwent treatment at the Brazilian National Cancer Institute were included in the study. Clinical and sociodemographic variables were obtained from the Hospital Cancer Registry and from hospital records. A descriptive study of the population was carried out, using means and standard deviations or frequencies and percentages. The Kaplan-Meier curve was used to identify annual incidence rates. Associations between the independent variables and the outcome (MSCC) were evaluated by a univariate analysis, applying crude and adjusted odds ratios (aOR) assuming 95% confidence intervals. RESULTS: The MSCC incidence was of 1.5% (n = 51), associated to advanced staging (aOR = 2.65, 95% CI: 1.45-4.85, p = 0.001) and initial treatment with concomitant chemotherapy and radiotherapy (aOR = 4.40, 95% CI: 1.74-11.13, p = 0.002). CONCLUSIONS: Our findings revealed the incidence and factors associated with MSCC, indicating a subset of patients who may be potential targets for the prevention and early treatment of this condition, indicating unprecedented and relevant data for the Brazilian epidemiological scenario due to the high CC incidence rates.

Incidence and risk factors for the development of cerebral metastasis in cervical cancer patients.

OBJECTIVE: Cerebral metastasis (CM) in cervical cancer (CC) cases, although rare, results in high lethality rates. The present study aimed to assess CM incidence in a Brazilian reference CC center and evaluate the risk factors for CM development. Retrospective observational study of patients diagnosed with CC between 2010 and 2017. METHODS: Cumulative CM incidence and incidence density were evaluated. Characteristics associated to CM development risks were identified using crude (cOR) or adjusted (aOR) odds ratios. RESULTS: A total of 3,397 patients were included in this study. Patient age ranged from 18 to 101 years, with a mean age of 48.8±14.0. After a mean follow-up time of 3.2±2.1 years, 51 CM cases were identified, resulting in a cumulative incidence of 1.5% (95% confidence intervals [CI]=1.12-1.97) and an incidence density at the end of the 6th year of 27.4 per 1,000 women/year. Advanced clinical stage (aOR=3.15; 95% CI=1.16-8.58; p=0.025), the presence of previous lung metastasis (aOR=4.04; 95% CI=1.82-8.94; p=0.001) and the adenocarcinoma (aOR=2.90; 95% CI=1.46-5.76; p=0.002), adenosquamous carcinoma (aOR=7.33; 95% CI=2.87-18.73; p<0.001), undifferentiated carcinoma (aOR=14.37; 95% CI=3.77-54.76; p<0.001) and neuroendocrine carcinoma (aOR=21.31; 95% CI=6.65-68.37, p<0.001) histological types were associated with a higher risk for CM development. CM risk was higher in the first years of follow-up, with no cases observed after the 6th year. CONCLUSION: CC patients in advanced clinical stages, displaying previous lung metastasis and non-squamous histological types are at high risk of developing CM.

Assessing pollen nutrient content: a unifying approach for the study of bee nutritional ecology.

Poor nutrition and landscape changes are regularly cited as key factors causing the decline of wild and managed bee populations. However, what constitutes 'poor nutrition' for bees currently is inadequately defined. Bees collect and eat pollen: it is their only solid food source and it provides a broad suite of required macro- and micronutrients. Bees are also generalist foragers and thus the different pollen types they collect and eat can be highly nutritionally variable. Therefore, characterizing the multidimensional nutrient content of different pollen types is needed to fully understand pollen as a nutritional resource. Unfortunately, the use of different analytical approaches to assess pollen nutrient content has complicated between-studies comparisons and blurred our understanding of pollen nutrient content. In the current study, we start by reviewing the common methods used to estimate protein and lipids found in pollen. Next, using monofloral Brassica and Rosa pollen, we experimentally reveal biases in results using these methods. Finally, we use our collective data to propose a unifying approach for analysing pollen nutrient content. This will help researchers better study and understand the nutritional ecology-including foraging behaviour, nutrient regulation and health-of bees and other pollen feeders. This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.

Honey Bee (Apis mellifera) Exposure to Pesticide Residues in Nectar and Pollen in Urban and Suburban Environments from Four Regions of the United States.

The risk of honey bee (Apis mellifera L.) exposure to pesticide residues while foraging for nectar and pollen is commonly explored in the context of agroecosystems. However, pesticides are also used in urban and suburban areas for vegetation management, vector control, and the management of ornamental plants in public and private landscapes. The extent to which pesticides pose a health risk to honey bees in these settings remains unclear. We addressed this at a landscape scale by conducting pesticide residue screening analyses on 768 nectar and 862 pollen samples collected monthly over 2 years from honey bee colonies located in urban and suburban areas in eight medium to large cities in California, Florida, Michigan, and Texas (USA). A risk assessment was performed using the US Environmental Protection Agency's BeeREX model whenever an oral toxicity value was available for a compound. Chemical analyses detected 17 pesticides in nectar and 60 in pollen samples during the survey. Approximately 73% of all samples contained no detectable pesticide residues. Although the number of detections varied among the sampled regions, fewer pesticides were detected in nectar than in pollen. Per BeeREX, four insecticides showed a potential acute risk to honey bees: imidacloprid, chlorpyrifos, and esfenvalerate in nectar, and deltamethrin in nectar and pollen. In general, exposure of honey bees to pesticides via nectar and pollen collection was low in urban and suburban areas across the United States, and no seasonal or spatial trends were evident. Our data suggest that honey bees are exposed to fewer pesticides in developed areas than in agricultural ones. Environ Toxicol Chem 2022;41:991-1003. © 2022 SETAC.

Understanding the Enemy: A Review of the Genetics, Behavior and Chemical Ecology of Varroa destructor, the Parasitic Mite of Apis mellifera.

Varroa destructor (Mesostigmata: Varroidae) is arguably the most damaging parasitic mite that attacks honey bees worldwide. Since its initial host switch from the Asian honey bee (Apis cerana) (Hymenoptera: Apidae) to the Western honey bee (Apis mellifera) (Hymenoptera: Apidae), Varroa has become a widely successful invasive species, attacking honey bees on almost every continent where apiculture is practiced. Two haplotypes of V. destructor (Japanese and Korean) parasitize A. mellifera, both of which vector various honey bee-associated viruses. As the population of Varroa grows within a colony in the spring and summer, so do the levels of viral infections. Not surprisingly, high Varroa parasitization impacts bees at the individual level, causing bees to exhibit lower weight, decreased learning capacity, and shorter lifespan. High levels of Varroa infestation can lead to colony-wide varroosis and eventually colony death, especially when no control measures are taken against the mites. Varroa has become a successful parasite of A. mellifera because of its ability to reproduce within both drone cells and worker cells, which allows populations to expand rapidly. Varroa uses several chemical cues to complete its life cycle, many of which remain understudied and should be further explored. Given the growing reports of pesticide resistance by Varroa in several countries, a better understanding of the mite's basic biology is needed to find alternative pest management strategies. This review focuses on the genetics, behavior, and chemical ecology of V. destructor within A. mellifera colonies, and points to areas of research that should be exploited to better control this pervasive honey bee enemy.

Priority conservation of medicinal woody plants from protected forests based on ecological and ethnobotanical data.

The combination of ethnobotanical and ecological knowledge is an important tool in indicating priority species for conservation. We sought to gather ethnobotanical knowledge on the diversity and use of woody medicinal plants in the Chapada Araripe region, assessing the real availability of woody medicinal resources in the Araripe Forests in the cerrado and carrasco areas, and indicate priority species for conservation. A total of 107 species were recorded in the ethnobotanical surveys, classified into 39 families and 83 genera, of which 92 species, 36 families and 70 genera for the cerrado areas, and 47 species, 25 families and 39 genera, for the carrasco areas. 59% were present in the phytosociological surveys for cerrado and 38% for carrascos. Species with high versatility of medicinal use did not necessarily have high local availability, and some were not recorded in the sampling. Thirteen species in cerrados and four in carrascos were indicated as conservation priorities. Use not aligned of species with the reality of the present time can indeed affect the vegetation landscape, and in a future scenario, not taking local measures to conserve protected forest resources, besides increasing the lists of local conservation priorities, can affect economic practices, increasing social and environmental conflicts.

Therapeutic indications, chemical composition and biological activity of native Brazilian species from Psidium genus (Myrtaceae): A review.

ETHNOPHARMACOLOGICAL IMPORTANCE: Brazilian medicinal species of the Psidium genus are rich in secondary metabolites such as terpenes and phenolic compounds and present biological activities for several human diseases. For the native Psidium species, there are no specific research reports for any member of the genus about ethnobotanical research, hindering the joint analysis of its therapeutic indications together with the scientific evidence already investigated. STUDY OBJECTIVE: Analyze the therapeutic indications, the main chemical constituents, and the biological activities of native species of the Psidium to Brazil. MATERIALS AND METHODS: Systematic research was carried out in the Scopus, ScienceDirect, PubMed, and Web of Science databases over a period of ten years. Articles in English, Portuguese and Spanish were used. The research was divided into three phases, seeking information on ethnobotany, chemical composition and biological activities. The words were combined to structure the descriptors used in the search. RESULTS: A total of 13 native species belonging to the Psidium genus were identified in this analysis, Psidium acutangulum DC., Psidium brownianum Mart. ex DC., Psidium cattleyanum Sabine, Psidium densicomum Mart. ex DC., Psidium grandifolium Mart. ex DC., Psidium guineense Sw., Psidium laruotteanum Cambess., Psidium myrsinites DC, Psidium myrtoides O. Berg, Psidium salutare (Kunth) O. Berg, Psidium schenckianum Kiaersk., Psidium sobralianum Proença & Landrum, Psidium striatulum Mart. ex DC. Of these, six were indicated in folk medicine, digestive system disorders being their main therapeutic indication. Most species presented an investigation of chemical composition and biological activity. They are rich in phenolic compounds, flavonoids, and terpenes and have antimicrobial, antioxidant, antiproliferative, and repellent activities. CONCLUSIONS: Native species of the Psidium genus are important sources of active ingredients in combating adversities that affect the human health, especially regarding the digestive system. They have a rich chemical composition, responsible for the biological activities demonstrated for the species.

Transcriptomic analysis of the honey bee (Apis mellifera) queen spermathecae reveals genes that may be involved in sperm storage after mating.

Honey bee (Apis mellifera) queens have a remarkable organ, the spermatheca, which successfully stores sperm for years after a virgin queen mates. This study uniquely characterized and quantified the transcriptomes of the spermathecae from mated and virgin honey bee queens via RNA sequencing to identify differences in mRNA levels based on a queen's mating status. The transcriptome of drone semen was analyzed for comparison. Samples from three individual bees were independently analyzed for mated queen spermathecae and virgin queen spermathecae, and three pools of semen from ten drones each were collected from three separate colonies. In total, the expression of 11,233 genes was identified in mated queen spermathecae, 10,521 in virgin queen spermathecae, and 10,407 in drone semen. Using a cutoff log2 fold-change value of 2.0, we identified 212 differentially expressed genes between mated and virgin spermathecal queen tissues: 129 (1.4% of total) were up-regulated and 83 (0.9% of total) were down-regulated in mated queen spermathecae. Three genes in mated queen spermathecae, three genes in virgin queen spermathecae and four genes in drone semen that were more highly expressed in those tissues from the RNA sequencing data were further validated by real time quantitative PCR. Among others, expression of Kielin/chordin-like and Trehalase mRNAs was highest in the spermathecae of mated queens compared to virgin queen spermathecae and drone semen. Expression of the mRNA encoding Alpha glucosidase 2 was higher in the spermathecae of virgin queens. Finally, expression of Facilitated trehalose transporter 1 mRNA was greatest in drone semen. This is the first characterization of gene expression in the spermathecae of honey bee queens revealing the alterations in mRNA levels within them after mating. Future studies will extend to other reproductive tissues with the purpose of relating levels of specific mRNAs to the functional competence of honey bee queens and the colonies they head.

Prevalence of Hepatitis C Virus Infection in Patients With Renal-Cell Carcinoma.

BACKGROUND: Some studies have demonstrated that the prevalence of chronic hepatitis C virus (HCV) infection is increased in patients with renal-cell carcinoma (RCC). Brazil is considered a low prevalence area for HCV (1.38%). The aim of this study was to evaluate the prevalence of HCV infection in patients with RCC. PATIENTS AND METHODS: A cross-sectional study with retrospective data collection was carried out. Patients more than 18 years old with a histopathologic diagnosis of RCC and who underwent HCV serology were included. Sociodemographic, pathologic, and clinical characteristics were evaluated at the time of patient admission. A descriptive analysis of the data was performed using means accompanied by their respective standard deviations for the continuous variables, and absolute number and frequency for the categorical variables. Comparisons between means were performed by analysis of variance. A chi-square test was used to compare the frequency of categorical variables. P < .05 was considered statistically significant. RESULTS: The prevalence of HCV infection was 4.1% (95% confidence interval, 1.7-8.3). No significant differences in age, sex, ethnicity, schooling, and alcohol or tobacco consumption among HCV- and HCV-negative patients with RCC were observed. CONCLUSIONS: A 3-fold higher prevalence of HCV infection was identified among patients with RCC than in the general Brazilian population. Further studies are required to confirm these data.

Uso de tablets por Agentes Comunitários de Saúde no Brasil

Objetivo: Refletir sobre o uso institucionalizado de tablets pelos Agentes Comunitários de Saúde (ACS) no seu processo de trabalho. Método: Pesquisa exploratória, com características quantitativa e qualitativa. Busca de reportagens realizada no Google notícias entre 2013 e 2019, utilizando os descritores "Agente Comunitário" e "Tablet". Elaborou-se um formulário eletrônico no Epi-info 7 com as principais informações de cada uma das notícias, gerando um respectivo banco de dados e clipping das matérias identificadas. Foi feita a análise temporal e geográfica das matérias. A abordagem qualitativa compreendeu a análise dos conteúdos das notícias, com base na análise de conteúdo de Laurence Bardin. Resultados e discussão: Foram encontradas vinte e sete (27) notícias de onze (11) estados de vinte e seis (26) municípios, sendo a maior parte da região Sul e Nordeste do Brasil. Na análise do conteúdo, percebeu-se que o tablet é compreendido como um instrumento que irá fazer com que o trabalho do ACS seja mais dinâmico e prático para eles e para a equipe de saúde da família como um todo, alguns dos termos que mais se destacaram foram: melhoria, facilidade e agilidade no processo de trabalho. O processo de qualificação dos ACS para o uso da nova tecnologia foi citado em 11 notícias (41%). Conclusão: É importante problematizar a introdução de tablets no processo de trabalho do ACS, levantando avanços e desafios, oferecendo também a qualificação apropriada para que estes profissionais possam fazer o melhor uso da ferramenta e não descartar totalmente os papéis, pois podem ser úteis.

The detection of honey bee (Apis mellifera)-associated viruses in ants.

Interspecies virus transmission involving economically important pollinators, including honey bees (Apis mellifera), has recently sparked research interests regarding pollinator health. Given that ants are common pests within apiaries in the southern U.S., the goals of this study were to (1) survey ants found within or near managed honey bee colonies, (2) document what interactions are occurring between ant pests and managed honey bees, and 3) determine if any of six commonly occurring honey bee-associated viruses were present in ants collected from within or far from apiaries. Ants belonging to 14 genera were observed interacting with managed honey bee colonies in multiple ways, most commonly by robbing sugar resources from within hives. We detected at least one virus in 89% of the ant samples collected from apiary sites (n = 57) and in 15% of ant samples collected at non-apiary sites (n = 20). We found that none of these ant samples tested positive for the replication of Deformed wing virus, Black queen cell virus, or Israeli acute paralysis virus, however. Future studies looking at possible virus transmission between ants and bees could determine whether ants can be considered mechanical vectors of honey bee-associated viruses, making them a potential threat to pollinator health.

Honey bee (Apis mellifera) larval pheromones may regulate gene expression related to foraging task specialization.

BACKGROUND: Foraging behavior in honey bees (Apis mellifera) is a complex phenotype that is regulated by physiological state and social signals. How these factors are integrated at the molecular level to modulate foraging behavior has not been well characterized. The transition of worker bees from nursing to foraging behaviors is mediated by large-scale changes in brain gene expression, which are influenced by pheromones produced by the queen and larvae. Larval pheromones can also stimulate foragers to leave the colony to collect pollen. However, the mechanisms underpinning this rapid behavioral plasticity in foragers that specialize in collecting pollen over nectar, and how larval pheromones impact these different behavioral states, remains to be determined. Here, we investigated the patterns of gene expression related to rapid behavioral plasticity and task allocation among honey bee foragers exposed to two larval pheromones, brood pheromone (BP) and (E)-beta-ocimene (EBO). We hypothesized that both pheromones would alter expression of genes in the brain related to foraging and would differentially impact brain gene expression depending on foraging specialization. RESULTS: Combining data reduction, clustering, and network analysis methods, we found that foraging preference (nectar vs. pollen) and pheromone exposure are each associated with specific brain gene expression profiles. Furthermore, pheromone exposure has a strong transcriptional effect on genes that are preferentially expressed in nectar foragers. Representation factor analysis between our study and previous landmark honey bee transcriptome studies revealed significant overlaps for both pheromone communication and foraging task specialization. CONCLUSIONS: Our results suggest that, as social signals, pheromones alter expression patterns of foraging-related genes in the bee's brain to increase pollen foraging at both long and short time scales. These results provide new insights into how social signals and task specialization are potentially integrated at the molecular level, and highlights the possible role that brain gene expression may play in honey bee behavioral plasticity across time scales.

Seasonal variation of pollen collected by honey bees (Apis mellifera) in developed areas across four regions in the United States.

For honey bees (Apis mellifera), colony maintenance and growth are highly dependent on worker foragers obtaining sufficient resources from flowering plants year round. Despite the importance of floral diversity for proper bee nutrition, urban development has drastically altered resource availability and diversity for these important pollinators. Therefore, understanding the floral resources foraged by bees in urbanized areas is key to identifying and promoting plants that enhance colony health in those environments. In this study, we identified the pollen foraged by bees in four developed areas of the U.S., and explored whether there were spatial or temporal differences in the types of floral sources of pollen used by honey bees in these landscapes. To do this, pollen was collected every month for up to one year from colonies located in developed (urban and suburban) sites in California, Texas, Florida, and Michigan, except during months of pollen dearth or winter. Homogenized pollen samples were acetolyzed and identified microscopically to the lowest taxonomic level possible. Once identified, each pollen type was classified into a frequency category based on its overall relative abundance. Species richness and diversity indices were also calculated and compared across states and seasons. We identified up to 64 pollen types belonging to 39 plant families in one season (California). Species richness was highest in CA and lowest in TX, and was highest during spring in every state. In particular, "predominant" and "secondary" pollen types belonged to the families Arecaceae, Sapindaceae, Anacardiaceae, Apiaceae, Asteraceae, Brassicaceae, Fabaceae, Fagaceae, Lythraceae, Myrtaceae, Rhamnaceae, Rosaceae, Rutaceae, Saliaceae, and Ulmaceae. This study will help broaden our understanding of honey bee foraging ecology and nutrition in urban environments, and will help promote the use of plants that serve the dual purpose of providing aesthetic value and nutritious forage for honey bee colonies placed in developed landscapes.