By Dave Black
With nothing better to do one morning than read the list of ingredients on my morning ‘yoghurt’ pot (which, incidentally, apparently didn’t contain any micro-organisms at all – eh!), not for the first time I started wondering about probiotics in apiculture. Not about whether they existed, but about whether they did any good. After all, the UN’s World Health Organization and Food and Agriculture Organizations define probiotics as; “Live microorganisms which, when consumed in adequate amounts as part of food, confer a health benefit on the host.”1 It seems to me if they don’t provide (confer) any health benefit you’re not entitled to call them ‘probiotic’, so what evidence of benefit to bees is there?
The Microbiota
We really know very little about honey bee gut micro-organisms. The most recent review on the subject by a leader in the field, Nancy Moran (with Erik Motta) 2 was published at the beginning of the year. Accurate identification of the microbes in the honeybee gut has only been possible in the last ten years or so, yeasts and bacteria are so ubiquitous it’s tricky to work out what should be there from what is actually there. We can be pretty sure then the microbiome (the collection of ‘tiny things’ that live in the gut) is quite specific to bee species, but develops or changes with age and caste.
Broadly speaking, a few microbes and the bees they live with have evolved together for 80 million years, and these microbes don’t really live anywhere else. They inhabit particular regions of the bee’s digestive tract (mainly the hind-gut) and not others, and provide specific abilities within the community they inhabit. Strains of Lactobacillus or Gilliamella bacteria found in honeybees for example, are not the same as those found elsewhere or even in other kinds of bees.
For the host bee the gut microbiota, individually and collectively, provides a degree of protection from opportunistic bacteria, fungi, viruses, and other small organisms using a variety of methods, many of which we don’t fully understand. They can secrete antimicrobial chemicals, out-compete the invaders for space or nutrients, form physical barriers, and function to maintain the activity of the host bee’s own immune defences. The bee microbiome’s role in nutrition also affects its host’s development and behaviour, changing the levels of available oxygen, acidity, and fatty acids, detoxifying harmful substances, and partly metabolizing some proteins and hormones. Honeybees and the microbiome they evolved with are interdependent, and inseparable.
When a bee emerges from its natal cell it arrives with no microbiome3. Although it’s been fed as a larva the mid-gut is closed, only joining with the hind gut just before pupation when anything retained up to that point is then excreted into the cell. During metamorphosis the gut lining is shed, so every new bee acquires its microbiome in the days before it first leaves the hive environment, from a reservoir held in or on wax surfaces, pollen cells, and propolis4. Trophallaxis (the exchange of food between bees) is not particularly significant because the microbiome lives in the hind-gut, not the fore-gut, but particular bacteria are probably transmitted by a faecal-oral route too.
In the first few days the colonisation by environmental bacteria appears to be chaotic, but within a week this settles into a stable, organised, and characteristic community of the microbes best suited to each other and the environmental niches they come to inhabit.
Demanding a Cure
Whether we see bees as managed agricultural labour or natural pollinators, there are plenty of environmental challenges that can disrupt this cozy bee-germ relationship and threaten healthy bees. There are always stresses, parasites, or diseases of various kinds for bees to cope with, and these days an array of agricultural chemicals and pollutants too, so there is every reason to look for ways to try and ensure we maintain or repair this dependency. Inspired by a lucrative industry promoting our own health, it’s not surprising that we might see probiotic formulations as a cure-all for honeybees too.
Many studies have suggested that exposing bees to chemicals for one reason or another disrupted their microbiome and weakened their normal immune response. Implicated in that negative effect have been antibiotics used elsewhere for foul brood control, medicines used for varroa control, and insecticides, herbicides like glyphosate5, fungicides, and their adjuvants.
At the moment the prospect of mitigating the harm using probiotics is distant. We have seen that the honeybee’s microbiome is highly specific (ours is individually unique!), inoculated in an exceptional way, for a particular group of young bees, and, in truth, that we should be talking about the colony’s microbiome.
Caveat Emptor
Whatever the branding, as far as I can tell the products on the market currently originate from three manufacturers. One, EM (as in Effective Microorganisms) originated in Japan, but mainly supplies the US and Latin America. It produces a lot of dubious, low quality science papers, but no actual information on what the product contains. In 2016 there were 59 ‘localised’ versions of the product in 120 countries and I’m not convinced even they know what is contained; Effective Microorganisms is more a process than product. In my own opinion the company is little more than a pseudoscientific, if well-meaning, cult. It’s not a good sign when even the founder (Teruo Higa) admits beneficial effects are an article of faith, there are no meaningful tests, and results can be variable or absent6.
SCD Probiotics (Sustainable Community Development) LLC was formed by Matthew Wood in Missouri. He completed a Master’s degree in probiotics research at the university EM’s founder teaches in, the University of Ryukyus, Okinawa, in Japan. SCD supplies microbiological ‘consortia’ (cocktails) of ‘starter’ or ‘mother’ cultures to other suppliers (Slide Ridge’s Fat Bee Products, Pro-Biotyk, etc.) as well as its own brands, and has a US patent on its products which is quite a read7. The patent ‘protects’ (conceals) the actual ingredient list.
Strong Microbials in Milwaukee, Wisconsin (think milk and beer) appears the most credible manufacturer to judge by that most scientific of measures... its web site. Its products have also been used in some recent peer-reviewed studies, so that’s a good start. It supplies a product called SuperDFM (Direct-Fed Microbials), which, to its credit, declares its ingredients and you can even download the Materials Safety Datasheet!
The origins of another brand I’ve heard of, Durvet, are unclear and is now only available for poultry.
The Inquisition
I have six studies in my library that examine whether some benefit is likely from using currently available probiotics, most, if not all (because some don’t say) looking specifically at versions of Strong Microbial’s offering8,9,10,11,12,13. The most recent (published this year) describes work done with Randy Oliver’s bees14 that started in 2021 and echoes the conclusion of all the others.
Those conclusions being that, whether applied prophylactically or therapeutically the non-native microbial communities now available, largely derived from human or animal probiotic preparations and ‘Generally Regarded As Safe’ (GRAS – to humans), do not survive or propagate in the honeybee gut. Neither do they survive in the colony microbiome which, by design, tries to keep foreign organisms out. So far, even trials using preparations of honeybee-specific strains of bacteria, successful in petri-dishes, have not translated into successes in real colonies in the field. No real-world efficacy could be demonstrated. I think we have a lot more to learn about the honeybee microbiome before we might reasonably call them ‘probiotic’.
The studies remain surprisingly optimistic that something could be made that ‘works’ but “the current market-available products for beekeepers are making claims that far outreach the ability of their products”15 . It’s obvious there is a demand for these products, and the easiest, cheapest way to supply that is with constituents that have some prior regulatory approval, and when the infrastructure for producing them at scale already exists. I wonder if anyone could ever really afford to supply bespoke, properly tested probiotic preparations to the size of market honeybees might create, and if a thorough knowledge of the honeybee microbiome might be more cost-effectively directed at not messing it up in the first place.
Snake-oil.
Dave Black is a commercial-beekeeper-turned-hobbyist, now retired. He is a regular science writer providing commentary on “what the books don't tell you”, via his Substack Beyond Bee Books, to which you can subscribe here.
References
1. Probiotics in food: health and nutritional properties and guidelines for evaluation; Food and Nutrition Paper 85, Food and Agriculture Organization of the United Nations [2006], Rome. ISBN 92-5-105513-0.
2. Motta, E.V.S., Moran, N.A., 2024. The honeybee microbiota and its impact on health and disease. Nat Rev Microbiol 22, 122–137. https://doi.org/10.1038/s41579-023-00990-3
Kwong, W.K., Moran, N.A., 2016. Gut microbial communities of social bees. Nat Rev Microbiol 14, 374–384. https://doi.org/10.1038/nrmicro.2016.43
4. Powell, J.E., Martinson, V.G., Urban-Mead, K., Moran, N.A., 2014. Routes of Acquisition of the Gut Microbiota of the Honey Bee Apis mellifera. Appl Environ Microbiol 80, 7378–7387. https://doi.org/10.1128/AEM.01861-14
Motta, E.V.S., Raymann, K., Moran, N.A., 2018. Glyphosate perturbs the gut microbiota of honey bees. Proc Natl Acad Sci USA 115, 10305–10310. https://doi.org/10.1073/pnas.1803880115
Higa, T.,and Parr, J.F., 1994. Effective Microorganisms. Bokashicenter.com.
https://patentimages.storage.googleapis.com/02/4c/49/6858ea8d47afb7/US9096836.pdf
Powell, J.E., Martinson, V.G., Urban-Mead, K., Moran, N.A., 2014. Routes of Acquisition of the Gut Microbiota of the Honey Bee Apis mellifera. Appl Environ Microbiol 80, 7378–7387. https://doi.org/10.1128/AEM.01861-14
Damico, M.E., Beasley, B., Greenstein, D., Raymann, K., 2023. Testing the effectiveness of a commercially sold probiotic on restoring the gut microbiota of honey bees: a field study.
Daisley, B.A., Pitek, A.P., Chmiel, J.A., Al, K.F., Chernyshova, A.M., Faragalla, K.M., Burton, J.P., Thompson, G.J., Reid, G., 2020. Novel probiotic approach to counter Paenibacillus larvae infection in honey bees. ISME J 14, 476–491. https://doi.org/10.1038/s41396-019-0541-6
11. Chmiel, J.A., Pitek, A.P., Burton, J.P., Thompson, G.J., Reid, G., 2021. Meta-analysis on the effect of bacterial interventions on honey bee productivity and the treatment of infection. Apidologie 52, 960–972. https://doi.org/10.1007/s13592-021-00879-1
12. Motta, E.V.S., Powell, J.E., Leonard, S.P., Moran, N.A., 2022. Prospects for probiotics in social bees. Phil. Trans. R. Soc. B 377, 20210156. https://doi.org/10.1098/rstb.2021.0156
Stephan, J.G., Lamei, S., Pettis, J.S., Riesbeck, K., De Miranda, J.R., Forsgren, E., 2019. Honeybee-Specific Lactic Acid Bacterium Supplements Have No Effect on American Foulbrood-Infected Honeybee Colonies. Appl Environ Microbiol 85, e00606-19. https://doi.org/10.1128/AEM.00606-19
A Field Trial of Probiotics, Randy Oliver, Grass Valley, California. https://scientificbeekeeping.com/8601-2/
Damico et al, Ibid.
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