Gut Microbiota Structure Differs Between Honey Bees in Winter and Summer

Thursday 4 March 2021

Right now, the worker honey bees enduring winter from within their hives are called ‘winter bees’ and they are quite different than summer worker honey bees. The differing factors of winter bees, when compared to summer bees, are ultimately what enable them to survive through the winter and carry the colony into the next spring. One of these differing factors between winter bees and summer bees is the composition of the microbial community in the honey bee gut. Keep reading below to find out what a gut microbial community is, how it affects honey bee health, and how it differs between winter and summer bees.

Also, a quick reminder that registration is open for the online Fundamentals of Beekeeping program and ‘Course 1: The Very Beeginnings’ will be delivered in just a few weeks! See details below for more information.

Gut Microbiota Structure Differs Between Honey Bees in Winter and Summer *

Honey bee health is affected by many factors, such as habitat availability, pesticide exposure, pests, diseases, and the bee gut microbiota. The honey bee gut microbiota, also called the gut microbial community, refers to the collection of microorganisms (i.e., bacteria, viruses, fungi, etc.) that are found in the gut of the honey bee. The microbiota in the honey bee gut plays a key role in honey bee health and is responsible for:

  • Conversion of food to useable nutrients
  • Energy production to support gut functions
  • Enhance the bee's sucrose response (enhanced foraging choices)
  • Stimulation of immune system

The honey bee gut microbiota community is largely determined by nutrient availability during foraging, and also the diet and lifespan of winter vs. summer bees. Summer bees spend their young lives within the colony as nurses, then transition to foragers as they get older. Winter bees emerge in the autumn and survive through the winter by clustering for heat, feeding, and retaining feces; the winter bee lifespan is much longer than summer bees. The results of a recent publication suggest that the gut microbiota community among nurses, foragers and winter bees differs in the following ways:

  • Nurse bees and winter bees have greater overall amounts of gut bacteria than foragers
  • Winter bees have the lowest diversity of gut bacteria strains

In addition to these differences, this publication also suggests that the most notable differences among nurses, foragers, and winter bees are seen in the winter bee gut microbiota. These differences could potentially be explained by differences in diet. Nurse and winter bees consume more pollen than foragers, and foragers consume mostly nectar and honey. Since nurse bees and winter bees consume more pollen, and pollen contains more nutrients than nectar, honey, or sugar water, a higher pollen diet is likely to support a greater bacterial load in the bee gut. However, this was not observed to result in a greater diversity of gut bacteria. This observation in honey bees is consistent with other studies on flies and mice, where the overall gut microbiota load increases with an increase of protein in the diet, but the diversity of the microbiota community decreases. Some factors that may lend an explanation to the phenomenon of the winter honey bee gut microbiota include:

  • bee age: winter bees do not physically deteriorate with age as other bees do
  • aged pollen diet: this diet has been observed to affect gut microbiota of nurse bees
  • metabolic differences of winter vs. summer bees: metabolic capabilities of their gut microbiota
  • winter bees do not defecate regularly: could impact bacteria accumulation and turnover
  • the type of bacterial analysis used cannot discriminate between live and dead bacteria cells

Further research is required to better our limited understanding of the winter bee gut microbiota. Since many colony losses occur during the winter period, increasing our knowledge of the winter bee gut microbiota could help us better understand overwinter colony mortalities.

* Kešnerová, L., Emery, O., Troilo, M., Liberti, J. & Engel, P. (2020). Gut microbiota structure differs between honeybees in winter and summer, The ISME Journal. Full text available online.

Fundamentals of Beekeeping – Registration is OPEN

Registration for our online beekeeping course opened last Monday and is still open and ready for you to join! We are getting ready and excited to teach our first course, in just a few weeks, all about getting set up as a beekeeper, the bee industry here in Atlantic Canada, honey bee biology and how to effectively manage your colonies for success in the spring.

You can choose to register for the whole program at once (and get a bundle discount!) or you can choose to register for just the first course. We cannot wait to teach participants all about honey bees and beekeeping in Atlantic Canada! Registration and course details can be found on the Dalhousie University Extended Learning – Fundamentals of Beekeeping program information and registration website. 

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