Microbiome Support Products

Microbiome-supporting products are probiotic, prebiotic and fermented feed additives sold with the claim that they support the beneficial bacteria in the honey bee's gut. It is well known that bee gut bacteria play an important role in digestion and defence; however, evidence that these products improve bee health or productivity in the hive is currently limited and inconsistent. The best-supported ways of protecting the microbiome are varied natural pollen, avoiding unnecessary medicines and good colony management.

What is the honey bee microbiome?

The microbiome is the totality of microorganisms living on and in an organism. In the gut of the adult worker bee, especially in the ileum and rectum, lives a bacterial community that is small in number of species but highly consistent. Largely the same "core" groups are found in honey bees in different parts of the world:

• Snodgrassella alvi and Gilliamella apicola: form a thin layer on the wall of the ileum.
• Lactobacillus and closely related lactic acid bacteria, together with Bifidobacterium: the most numerous groups in the rectum.
• Less abundant species such as Frischella perrara and Bartonella apis.

In the honey stomach (crop), in the comb and in brood food, other bacteria such as Apilactobacillus kunkeei and Bombella predominate. Very few bacteria are found in the larval gut.

Where do bees get these bacteria from?

The gut of a newly emerged young worker is almost empty. The core bacteria are acquired within the first few days through contact with nestmates, mouth-to-mouth food sharing and the comb surface. So the main source of the microbiome is not a product from outside but the colony itself.

What do gut bacteria do for the bee?

• Digestion: They break down certain sugars and compounds in the pollen wall and in plant sap that the bee finds hard to digest on its own.
• Defence: Laboratory studies have shown that they stimulate the immune system and leave no room in the gut for disease agents.
• Development: Weight gain and some metabolic functions have been reported to lag behind in bees raised without bacteria.

Most of these findings come from cage and laboratory experiments. Whether every finding holds to the same extent under hive conditions is still being researched.

What disrupts the bee microbiome?

• Antibiotics: Experiments have shown that bees given antibiotics have fewer gut bacteria, become more susceptible to disease and die earlier. Antibiotic use in bees is not permitted in Türkiye, and residues in honey are not accepted either.
• Some agricultural chemicals: There are studies indicating that some herbicides and fungicides can affect bee gut bacteria.
• Poor and monotonous nutrition: A lack of pollen or long periods of feeding only on syrup can adversely affect the gut community and the bee's general resistance.
• Young bees kept apart from the colony: Young bees that cannot make contact with nestmates do not fully acquire the core bacteria.

What microbiome products are on the market?

What does the scientific evidence say?

The honest summary is this: the evidence is limited.

• Species mismatch: The bacteria in most commercial products are not the bee's own gut species but strains of food or human origin. These bacteria usually do not settle in the bee gut and are excreted within a few days.
• Inconsistent results: Cage experiments have reported that some probiotics increase lifespan or resistance to certain disease agents; but in hive-level trials an effect on colony strength, honey yield and wintering has mostly not been shown.
• Negative finding: In one study a commercial bee probiotic did not help the gut community recover after antibiotics, and the bacteria given did not settle in the gut.
• A promising direction: Research is continuing on cultures prepared from the bee's own core bacteria; these are not yet routine beekeeping products.

Proven ways of supporting the microbiome

1. Varied natural pollen: Set up apiaries where there are plants flowering at different times; do not stay long in single-crop areas with a pollen gap.
2. Leave bee bread: Go into winter and spring with pollen frames; do not take pollen frames out of greed at harvest time.
3. Avoid unnecessary medicines: Use only authorised products, when needed and according to the label; do not use antibiotics.
4. Use syrup correctly: Sugar syrup fills a gap but does not replace pollen; in a pollen dearth a suitable pollen substitute can be considered.
5. Stay away from agricultural chemicals: With an apiary close to sprayed areas, communicate with the farmers.
6. Strong colony: A low-stress colony with plenty of young bees is also the type of colony best able to pass bacteria from generation to generation.

If you still want to use a product, what should you look out for?

• Legal status: Check whether the product is registered as a feed additive or a veterinary product for bees.
• Transparent contents: The label should state the names of the bacterial species and the number of live cells; "special formula" is not enough.
• Do not use during a honey flow: While supers are on the hive, no additive that could get into the honey is given.
• Storage: Products containing live bacteria lose their effectiveness in heat and with long storage.
• Set up your own trial: Split colonies of similar strength into two groups; give the product to half and not to the other half. Compare colony strength, honey and wintering results. An impression that "it worked" without a comparison is misleading.

Common misconceptions

• "Because it's natural, it's harmless and effective." Being of natural origin guarantees neither effectiveness nor safety.
• "If I give probiotics, I won't need to use treatments." No; varroa and notifiable diseases are dealt with by their own methods.
• "A sick colony will recover with probiotics." If foulbrood is suspected, it must be reported to the agriculture authority; waiting with a support product spreads the disease.
• "It should be given regularly to every hive." No additional benefit has been shown for a healthy, well-fed colony.