Bees pollinate crops with which we feed our world, making healthy and stable honey bee colonies crucial for global agriculture and ecosystems. However, bee populations are facing unprecedented challenges from pesticides, diseases, and degraded landscapes. For World Honey Bee Day 2024, Kenya Fernandes explores how understanding the relationships between bees and their commensal microbes can provide insights into new ways to support and protect our essential pollinators. #MicrobiologyEvents
The microbial ecosystem of bee hives
For bees, a hive is much more than a cozy home. Honey bees transform their hives into complex environments and fill them with unique products like honey, beeswax, pollen, and propolis. Each of these bee products plays a crucial role in the colony’s health and functioning.
Even though many enjoy the sweetness of honey, it actually provides essential energy for bees. Similarly, propolis – a sticky substance made from plant resins and beeswax – acts as a protective sealant, fortifying the hive against potential invaders.
As bees interact with flowers and soils in the environment, they also introduce microbes into their hives. The bacteria, yeasts, and moulds interact with the hive’s products, the bees, and each other, shaping different microbial niches and thus a dynamic microbial ecosystem.
The microbial interactions help bees maintain a healthy and functional hive environment, as shown in the research article “Pollen products collected from honey bee hives experiencing minor stress have altered fungal communities and reduced antimicrobial properties” in FEMS Microbiology Ecology.
Microbes contribute to honey and pollen production
When forager bees collect nectar from flowers, it is rather susceptible to degradation due to the absence of antimicrobial mechanisms and the high water content. As bees transform nectar into honey, bacteria and yeasts thrive, producing natural antimicrobial compounds including antibiotics, antimicrobial peptides, and other compounds that contribute to honey’s protective properties.
So, even though mature honey is a supersaturated sugar solution, it deters microbial growth. This allows bees to store it long-term in the hive for times when food is scarce.
For honey production, the impact of microbes seems indeed rather small. Yet, the study showed that microbes, and particularly fungi, are important for developing the functional properties of pollen and the resulting “bee bread”.
Bee bread is the primary protein source for adult and baby bees. For this, bees mix the freshly collected pollen with glandular secretions, containing various enzymes, peptides, and proteins, as well as small amounts of nectar or honey. They then store the mix in wax combs.
Over time, bacteria and yeasts ferment the pollen mix in the combs producing bee bread. Fungi, in particular, can reach high densities in bee bread and likely enhance its nutritional benefits compared to raw pollen. This inhibits the growth of harmful microorganisms and preserves the bee bread.
The bee gut microbiome impacts bee health
For the health of the bees and thus for the fermentation process, the microbial community living in bee guts plays a crucial role. This honey bee gut microbiome is dominated by five core bacterial lineages that evolved with bees for tens of millions of years: Gilliamella, Snodgrassella, Lactobacillus Firm 4, Lactobacillus Firm 5, and Bifidobacterium.
These microbes contribute to digesting food, absorbing nutrients, detoxifying harmful substances, and protecting against pathogens. Hence, a healthy bee gut microbiome is crucial for maintaining a bee’s overall metabolic health.
This also means that disrupting the bee gut microbial community from environmental stress, diseases, or poor nutrition can compromise bee health and colony stability. Factors like pesticides, antibiotics, and poor foraging conditions can lead to microbial imbalances, weakening the bees’ immune systems and increasing their vulnerability to diseases.
Understanding the role of the gut microbiome in bee health is essential to help bees resist diseases and pollinate crops. Protecting and nurturing bee populations is thus key to ensuring both the stability of our food supply and the health of natural ecosystems.
- Read the article “Pollen products collected from honey bee hives experiencing minor stress have altered fungal communities and reduced antimicrobial properties” in FEMS Microbiology Ecology by Fernandes et al. (2024).
About the author
Kenya Fernandes is a research fellow at The University of Sydney. She investigates the biology and ecology of microbial pathogens and avenues for their treatment with a particular emphasis on fungal pathogens. Her current research focuses on the antimicrobial potential of Australian honey and the relationship between bee health, ecosystem health, and honey activity.
About this blog section
The section #MicrobiologyEvents for the #FEMSmicroBlog reports about events and meetings relevant to our network. These include world awareness days, FEMS-sponsored meetings or meetings of Member Societies and many more.
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