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Becky Masterman earned a PhD in entomology at the University of Minnesota and is currently a host for the Beekeeping Today Podcast. Bridget Mendel joined the Bee Squad in 2013 and led the program from 2020 to 2023. Bridget holds a B.A. from Northwestern University and an M.F.A. from the University of Minnesota. Photos of Becky (left) and Bridget (right) looking for their respective hives. If you would like to contact the authors about virus stories, please send an email to mindingyourbeesandcues@gmail.com.
Hemolymph Tales
By: Becky Masterman & Bridget Mendel
Hemolymph (Blood) Biomarkers
Honey bee hemolymph research is amazing and biomarkers are the reason. Scientists are asking questions about honey bee health and development and use the molecules present in hemolymph (insect ‘blood’) to get answers. Whether investigating how pesticides impact protein levels and immune responses, how comb cell size impacts honey bee physiology or evaluating nutrition or longevity, it turns out that answers are in the blood…or more accurately, the hemolymph.
Honey bees have an open circulatory system where the ‘blood’ or hemolymph is moved from the back end of the abdomen through the body via a long, tubular dorsal aorta where it bathes the brain and then flows through the thorax and abdomen and directly contacts insect organs and tissues. Hemolymph not only lubricates the inside of the honey bee, but like in humans, this liquid delivers nutrition, immune responses, pheromones and hormones. Unlike humans, oxygen is not transported in hemolymph but delivered to organs via a network of tracheal tubes.
Just like a vertebrate animal’s blood sample, honey bee hemolymph molecules can measure health and development. An early noteworthy study used a research technique called quantitative and qualitative proteomics (a fancy way of describing the measurement of the amount and type of proteins) to evaluate and identify protein differences in honey bee caste hemolymph (Chan et al., 2006). While the research goal was to identify honey bee immunity biomarkers, this work was the first to use proteomics to profile proteins in honey bee hemolymph.”
Investigations into how workers digest pollen provides insight into food quality and age-related pollen feeding. Photo credit: Rebecca Masterman
In the twenty years since this work, scientists have built an enormous body of knowledge that fuels today’s research questions. Instead of evaluating colony health by counting the frames of bees, pounds of honey or overwintering success, hemolymph molecule measurements reveal potentially important physiological changes that might not be readily apparent in a colony inspection.
We want to share several studies that demonstrate how hemolymph can be used to investigate honey bee health. Sometimes the results lead to more questions, an important part of the research process. For beekeepers who just got used to sampling mite populations and are now worried they will have to sample hemolymph, we aren’t quite there yet. But after reading below, you might just want to be!
Pesticides
Fisher et al. (2025) looked at hemolymph to explain why exposure to the broad-spectrum fungicide, Pristine®, reduces worker body size, causes early foraging (thus a shorter lifespan) and impairs their ability to find home. They report reduced hemolymph protein levels in long term Pristine® exposure studies and reduced vitellogenin protein in short term Summer exposure. This work connects pesticide exposure to measurable physiological changes in workers.
A study asking how honey bees respond to oxalic acid (OA) mite treatments compared worker hemolymph after 3 mite treatments: OA trickle, OA in glycerin and flumethrin (Pindakova et al., 2025). Hemolymph molecule changes to each treatment were detected. Interestingly, antimicrobial activity in the hemolymph between 48-192 hours after application of the OA in glycerin treatment, but not the OA trickle or flumethrin treatments. Increased vitellogenin was measured 24 hours after the OA trickle treatment. While immune response activation can be stressful, the authors debate whether it might help fight infections and benefit colony health. We look forward to additional research into this work.
While the benefit of cell size for varroa control is being debated, is it possible that specialized workers develop from special cell sizes? Photo credit: Rebecca Masterman
Nutrition
A study evaluating three pollen sources in China measured the relationship between the pollen amino acid content and the metabolites found in worker hemolymph (Chan et al., 2022). This study provided key evidence to the ‘you are what you eat’ theory. The research team connected the pollen derived amino acid metabolites with worker age. They reported high levels within the first week of adult life and then decreased presence. The authors hypothesize that older workers might mainly consume pollen for sucrose.
Cell Size
While the impact of brood cell size manipulation on varroa populations is still being debated, (Oddie et al., 2019), evidence that cell size impacts worker physiology has been reported. A research team investigated how cell size impacts bee development. They reported higher protein levels in the smaller sized workers reared in small cell comb (Dziechciarz et al., 2022) The report noted that workers in feral colonies build different brood cell sizes. The researchers hypothesized that workers reared in different sized cells might have different protein levels to specialize workers for different tasks. Other social insect colonies, like ants, have different sized worker sub-castes. This report suggests that additional investigation into this possibility is warranted.
Cedar Hive Boxes
Sometimes no news (or data) is good news. A comprehensive study comparing hive boxes made from western red cedar to white pine wood included the evaluation of wintering success, varroa populations, brood and adult populations and hemolymph biomarkers (McAfee et al., 2025). No differences were detected between the bees housed in cedar or pine boxes. There was a difference in the protein expression of newly emerged workers compared to foragers regardless of hive material.
Lack of Longevity
A comprehensive study on how varroa parasitism impacts aging tested honey bee hemolymph and fat bodies to confirm that infestation resulted in decreased antioxidant and detoxification capacities (Kunat-Budzyńska et al., 2025). Premature aging is associated with a decline in these protective systems. Reason number one million and one to control varroa populations in your colonies, especially during key brood population increases.
Wait, there is more.
If we have piqued your curiosity, a recent review paper, Bryś (2025) has detailed the tremendous work that has taken place since the detailing of the caste hemolymph proteins by Chan et al. in 2006. Honey bee hemolymph research has created a library of biomarkers that help us understand how the environment, and beekeeping management practices impact bee health.
Resources and References
Bryś, M. S. (2025). (Rev. of Analysis of Panels of Chemical Biomarkers in the Honeybee in Hemolymph and Fat Body in Response to Physiological and Environmental Factors). Metabolites, 15(11), 743. https://doi.org/10.3390/metabo15110743
Chan, Q. W. T., Howes, C. G., & Foster, L. J. (2006). Quantitative Comparison of Caste Differences in Honeybee Hemolymph. Molecular & Cellular Proteomics, 5(12), 2252–2262. https://doi.org/10.1074/mcp.M600197-MCP200
Chang, H., Ding, G., Jia, G., Feng, M., & Huang, J. (2022). Hemolymph Metabolism Analysis of Honey Bee (Apis mellifera L.) Response to Different Bee Pollens. Insects (Basel, Switzerland), 14(1), 37. https://doi.org/10.3390/insects14010037
Fisher, A., Chahal, K., DeGrandi-Hoffman, G., Smith, B. H., Fewell, J. H., & Harrison, J. F. (2025). Exposure to a widely used mito-toxic fungicide negatively affects hemolymph protein and vitellogenin levels in honey bees (Apis mellifera). Environmental Toxicology and Pharmacology, 115, Article 104676. https://doi.org/10.1016/j.etap.2025.104676
Kunat-Budzyńska, M., Staniszewska, P., Olszewski, K., & Strachecka, A. (2025). Antioxidant Activities in the Hemolymph and Fat Body of Physiologically and Prematurely Aging Bees (Apis mellifera). Antioxidants, 14(4), Article 373. https://doi.org/10.3390/antiox14040373
Mcafee, A., Tarpy, D. R., & Foster, L. J. (2025). Western red cedar (Thuja plicata) beehives have no impact on honey bee (Apis mellifera) overwintering colony survival or detoxification enzyme expression. bioRxiv. https://doi.org/10.1101/2025.01.23.634475
Oddie, M. A. Y., Neumann, P., & Dahle, B. (2019). Cell size and Varroa destructor mite infestations in susceptible and naturally-surviving honeybee (Apis mellifera) colonies. Apidologie, 50(1), 1–10. https://doi.org/10.1007/s13592-018-0610-2
O’Neal, S. T., & Anderson, T. D. (2016). Dissection and Observation of Honey Bee Dorsal Vessel for Studies of Cardiac Function. Journal of Visualized Experiments, 118. https://doi.org/10.3791/55029-v
Pindakova, E., Dostalkova, S., Jemelkova, J., Furstova, J., Hurychova, J., Hyrsl, P., Titera, D., Petrivalsky, M., Dobes, P., & Danihlik, J. (2025). Enhanced immune response and antimicrobial activity in honey bees (Apis mellifera) following application of oxalic acid-glycerine strips. Pesticide Biochemistry and Physiology, 209, Article 106353. https://doi.org/10.1016/j.pestbp.2025.106353
