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Reevaluating Beebread: Part 1

First published in: American Bee Journal, October 2015

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“The Story”

Randy Oliver


The Heyday Of Bee Research
Pollen And Beebread
The Roots Of A Beguiling Story
Doubting Thomases (Skeptical Questioning)
Enter Dr. Kirk Anderson
References and Notes

People feel compelled to come up with explanations for what they observe; and beekeepers are no different. Historically, beekeepers embraced fanciful myths to explain what they saw; frankly, the situation in today’s “age of reason” is often little different. And not even scientists are immune to a beguiling story that appears to elegantly explain some aspect of bee biology.


People tend to anthropomorphize the honey bee, meaning that they liken its biology and behavior to that of humans. The fact is, that honey bees are far from human, and see and experience the world very differently than do we. What “makes complete sense” to a human may have absolutely no relevance to the honey bee. Unfortunately, the original sources of some “facts” about the bee come from someone who explained something so compellingly in human terms, that it immediately resonated with beekeepers, who accepted it uncritically and without supporting evidence. We then get “proof by repeated assertion,” with one authority after the next retelling it without question—in bee books, scientific papers, and media articles (it’s the rare reporter these days who actually goes to the trouble to deeply check his facts).

Science, on the other hand, is all about skepticism, requiring impeachable evidence, and continual reevaluation of what we “know.” Those who have been following my writing already know that I’m not afraid to bust some common myths about the honey bee or its situation. So I was surprised by the lack of buzz when a little-known ARS bee researcher recently toppled one of our most cherished tenets. His findings put the lie to a popular myth—that bees need to ferment pollen into beebread in order to digest it.

The Heyday Of Bee Research

There’s been a great deal of scientific interest in honey bees since we began to feel the impact of the evolving varroa/virus complex, the invasion of Nosema ceranae, and changes in agricultural practices; and even more so after Dave Hackenberg brought Colony Collapse Disorder to worldwide attention in 2007 [1](Fig. 1).

fig 1

Figure 1. Bee research has enjoyed a heyday as beekeeping in the U.S. and Europe began to become more difficult in the early 2000’s. Data from ScienceDirect.

The upside from all this research is that we’ve learned a helluva lot about bee biology in the past decade. In this article I’ll attempt to trace how the enticing story of the need for bees to ferment pollen into beebread grew, and how a team of bright researchers slapped us back to reality.

Pollen And Beebread

Beekeepers have long known how critical an abundant supply of pollen is for good colony performance, either coming in fresh, or stored within the colony [2]. The thing to keep in mind is that the forager bees that gather pollen do not eat it themselves, since when they transition to foraging, they stop producing the proteolytic enzymes necessary to digest it. So the foragers unload the pollen they’ve gathered directly into open cells located at the interface between the brood and stored honey, creating a typical band of beebread (Fig. 2).

Figure 2

Figure 2. Note the band of stored pollen in the interface between the brood and honey. The freshest pollen is bright, whereas older stored pollen has a wet appearance due to the addition of a thin layer of honey.

After a forager places her load of pollen into a cell, mid-age bees then use their heads to pack it firmly into place, pushing out the air as well as adding more nectar, honey, or glandular secretions [3]. Other foragers then place additional loads on top, often resulting in multicolored layers (Fig. 3).

Figure 3

Figure 3. The different colors indicate that each layer of beebread may consist of pollen from a different plant species. Foragers appear to seek out a diversity of pollen sources, which would help the colony to obtain a more nutritionally balanced diet.

Once the cell is about three quarters filled and well packed, the pollen processors then seal it with a layer of honey, under which it ferments into beebread. Humans have long known how to ferment food products in order to preserve them (e.g., sauerkraut, pickles, and cider), or to improve their digestibility (e.g., yogurt and ripe cheese) or flavor (e.g., miso and vinegar), or their chemistry (e.g., beer). So of course we resonated with the concept that our beloved bees also practiced zymurgy [4]. What a great story, huh? And like many great stories, it got better with each retelling.

The Roots Of A Beguiling Story

I spent a bit of time in trying to trace the development of the beebread story. Back in 1957, popular columnist Len Foote, in an article in ABJ entitled “Possible use of microorganisms in synthetic bee bread production” [5] wrote:

The need for effective and economical substitutes for pollen and bee bread is becoming increasingly more apparent and urgent in the field of beekeeping…Every effort is being made at the present time to more accurately determine the nature and composition of both pollen and bee bread in order to produce effective and economical substitutes…we now have formulas that show promise of being effective substitutes for fresh pollen; but, as yet, there is no formula that promises to take the place of bee bread in the diet of the colony.

After reviewing the research to date, Foote concluded that:

It is quite obvious that bee bread is more than stored pollen.

Dr. Mykola Haydak seconded that opinion the next year in ABJ [6], suggesting that pollen subs [7] might be improved by fermenting them in a similar manner. Oddly though, in the 1963 edition of The Hive and the Honey Bee, Haydak only mentioned that “Lactic acid produced by bacteria preserves beebread from spoilage.”

The heyday of bee nutrition occurred between 1969 until the invasion of varroa around 1990, when research attention turned to the mite. It seems from reading the literature that there was a bit of disagreement between legendary bee nutritionist Dr. Elton Herbert Jr. at the Beltsville lab (working on artificial diets), and Dr. Martha Gilliam at Tucson (who saw things through the eyes of a microbiologist) [8]. Researchers at the Tucson lab found intriguing suggestions that pollen nutritional value improved after fermentation [9], but could only state that:

Published reports are inconclusive and contradictory concerning the relative composition and nutritive value of pollen before and after it is stored by bees… The fact is that chemical and biochemical changes occurring in pollen after bees have stored it in comb cells are not clearly understood, though numerous investigators have offered suggestions as to possible mechanisms involved. Such information is an essential pre-requisite to the development of an adequate artificial protein diet for honey bees and to understand the complexities of the nutritional requirements.

There were plenty of suggestive reasons for Gilliam to believe that bees were using her beloved microbes to convert raw pollen into a more nutritional food. Herbert was more circumspect, and when his findings were summarized posthumously in the 1992 edition of The Hive and the Honey Bee he could only state that:

Stored pollen undergoes a number of biochemical changes which may be responsible for increased stabilization of the product or may lead to chemical changes that increase the digestibility and nutritive value to bees.

Gilliam responded in 1997 in her review [10]:

The fermentation and chemical changes of pollen stored in comb cells by honey bees may be processes similar to those that occur in green plant food materials that are ensiled and in foods of plant origin that are fermented to prolong shelf-life and to improve palatability, digestibility, and nutritional value.

She concluded that the team’s research indicated:

the superiority of the nutritive value and availability of amino acids in the protein of bee bread compared to corbicular pollen…Thus, we hypothesized that an association between Bacillus spp. and some bees may have evolved in which female bees inoculate food sources with these bacteria whose chemical products contribute to the pre-digestion, conversion, enhancement, and/or preservation of food that is stored in the nest.

By the early 2000’s, we were really starting to struggle with colony health issues, so the Tucson ARS lab again began to focus upon bee nutrition, with Dr. Gordon Wardell working to develop an artificial diet [11]. Then came CCD, and beekeepers became aware of the new field of metagenomics [12]. Scientific technology had by this time advanced beyond the petri dish culture techniques that limited Martha Gilliam; researchers could now use a new generation of fancy scientific equipment and high-speed computers in order to screen biological samples for the presence of previously unidentified and unculturable microorganisms. We soon discovered that biological systems (including both the human gut and the honey bee colony) were more diverse at the micro scale than we had ever imagined.

Even more so, it was discovered that the symbiotic microbes in our guts were essential to our digestion, immune function, and the production of critical nutrients (Fig. 4). In 2008 the National Institutes of Health initiated the Human Microbiome Project and the microbiome became a hot topic in both science and the health food market (meaning that it would get a lot of chatter on the internet).

Figure 4

Figure 4. This colony in May had a surfeit of pollen, much of which will soon be glazed with honey and converted into beebread for later consumption. Just how important is such microbial fermentation to the nutritional utilization of the pollen by bees? What is the structure of the microbial community involved? And is it necessary for bees to inoculate the pollen with symbiotic bacteria?

Google Trends shows that interest in “probiotics” took off at that time. Beekeeper Kevin Jester developed a fermented pollen sub. And the Tucson lab, under the direction of Dr. Gloria DeGrandi-Hoffman, explored the potential disruption of the microbial community by fungicides, miticides, antibiotics, or high fructose corn syrup [13]. Dr. DeGrandi-Hoffman pointed out at the national conventions that they were unable to maintain colonies in flight cages on the lab’s artificial diet alone, but could restore them to health if they gave them a bit of natural beebread—a sure indication of the importance of the microbes in beebread.

The beekeeping community, struggling with high rates of colony losses, grasped for reasons. Could we have somehow screwed up the hive microbial community? And as the conventional wisdom grew that the fermentation of beebread was critical for its proper utilization by bees, the timing was ripe for two Swedish researchers to publish new findings [14] claiming that bees inoculated pollen with specific coevolved lactic acid bacteria from their crops in order to start the fermentation process. They of course wasted little time in commercializing a product [15], and briefly collaborated with the Tucson Lab.

The pieces of the puzzle were now all coming together into one alluring story. Dr. Gloria DeGrandi-Hoffman summarized the current state of knowledge in three articles in ABJ in 2009 [16], revving up the engines for revisiting an area of research that had been largely ignored for 20 years. She teased our interest by explaining that:

The processing of pollen into beebread involves a progression of microbes to establish an environment for the fermentation and pre-digestion of pollen, along with the addition of nutrients from the microbes that are essential for optimum honey bee health.

We had now entered into a New Age of holistic beekeeping, in which we were considering the effects of antibiotics, pesticides, miticides, sugar syrups, and pollen subs upon the in-hive microbes. With the new technologies of metagenomics, we now had the chance to finally truly understand the importance of the microbial community in colony health.

Doubting Thomases (Skeptical Questioning)

As a biologist and beekeeper, I was so enthralled by the story of the pre-digestion of pollen by microbes that I bought right into the notion, despite that fact that it was based solely upon suggestive findings and speculation. How easy it was to overlook the fact that the story had a few obvious holes in it.

As pointed out by “Oldtimer” on Beesource [17], any beekeeper can confirm that colonies grow just fine when they’re consuming raw pollen as fast as it comes in, with no time for fermentation.   And colonies grow quite well on patties of raw pollen that has not been made into beebread [18]. Somehow, the beebread story must account for such discrepancies.

Earlier Beltsville and Tucson researchers had been unable to demonstrate that fermentation actually improved the nutritional value of pollen [19]. And Fernandes-Da-Silva [20], studying the beebread of stingless bees, found that “the storage of pollen seems to be of no importance in changing the nutritive value.”

Then Dr. Nancy Moran lab’s findings [21] did not support the “symbiotic crop bacteria inoculation” hypothesis of the Swedish researchers:

Even though the crop often contains nutrient-rich nectar that could be used as an energy source for microbes, it contains very few bacteria. The frequent filling and emptying of the crop as nectar is collected and transferred to the hive for honey production could perturb the microbial community and prevent bacterial colonization.

I’ve illustrated the Moran lab’s findings below (Fig. 5).

Figure 5

Figure 5. The lack of bacteria in the crop simply does not support the hypothesis that the inoculation of pollen with bacteria from the crop is essential for the fermentation of beebread—there simply aren’t enough bacteria in the crop. Data after Martinson [22], drawing from Snodgras [23].

Enter Dr. Kirk Anderson

In 2009, the Tucson lab created a position for a “microbial ecologist,” filling it with the top-notch and academically aggressive scientist Dr. Kirk Anderson (Fig. 6), whose previous experience dealt largely with the microbiome of ants. At first, Kirk bought right into the beebread story, and wrote about it elegantly [24].

Figure 6

Figure 6. Dr. Kirk Anderson taking pH readings of beebread with a “pH Spear”– a food industry instrument (fermentation rapidly results in increased acidity of the pollen). When I questioned Kirk about his sparkling white suit, he said that unlike beekeepers such as myself, microbiologists actually wash their suits regularly. Photo by Patrick Maes.

Realizing that he lacked experience with bees, and needing advice in establishing a migratory operation for research purposes, Kirk contacted me, and we’ve since become collaborators and friends, often communicating daily about bee research.

Practical application: I find that the bee research community often benefits from bringing in experts from outside the field. These researchers may then see things through different eyes. I’m happy to say that the Tucson lab now has one of the best and brightest working for us. Kirk is approachable, goes right for the heart of any scientific question, and isn’t afraid to challenge the established conventional wisdom.

Next month I’ll cover what Kirk discovered when he applied his scientific expertise to deeply investigate the microbiota of the hive and its involvement in the fermentation of beebread.


Thanks to Pete Borst for his help in research, to Dr. Gerry Loper, and to the ARS for hiring Kirk Anderson.

References and Notes

[1] Another example of a commonly repeated misconception. We beekeepers in California started experiencing CCD in 2004 (this is why the price for almond pollination suddenly spiked); and when I asked Dave whether his bees may have “caught it” in almonds at that time, he told me that he first saw it in his hives in 2003.

[2] As evidenced by Dr. C.L. Farrar’s excellent summary for optimal colony management: Farrar, CL (1968) Productive Management of Honey-Bee Colonies

[3] The process of pollen collection, unloading, and packing is meticulously described by Dr. Mykola Haydak in the 1963 revision of The Hive and the Honey Bee, Dadant & Sons.

[4] Zymurgy: the area of applied science related to fermented foods and beverages.

[5] Foote, HL (1957) Possible use of microorganisms in synthetic bee bread production. Amer. Bee J.97:476-478.

[6] Haydak, MH (1958) Pollen – Pollen Substitutes – Beebread. Amer. Bee J. 98: 145-146.

[7] I’ll use this generic term for both pollen supplement and substitute

[8] A list of Gilliam’s publications can be found at http://www.beeuntoothers.com/Gilliam/Gilliam%20Book%202/TOC.pdf

[9] Loper, GM, et al (1980) Biochemistry and microbiology of bee-collected lmond (Prunus dulcis) pollen and bee bread. I.‒ Fatty acids, sterols, vitamins and minerals. Apidologie 11(1): 63-73. Open access.

Standifer, LN, et al (1980) Biochemistry and microbiology of pollen collected by honey bees (Apis mellifera L.) from almond, Prunus dulcis. II: Protein, amino acids and enzymes. Apidologie 11 (2): 163-171. Open access.

[10] Gilliam, M (1997) Identification and roles of non-pathogenic microflora associated with honey bees. FEMS Microbiology Letters 155(1): 1-10. Open access.

[11] Eventually marketed as Megabee http://agresearchmag.ars.usda.gov/2003/mar/bees/

[12] With the publication of Cox-Foster, D, et al (2007) A metagenomic survey of microbes in honey bee colony collapse disorder. Science 318(5848): 283-287.

Metagenomics for bees are nicely described by DeGrandi-Hoffman, G, et al (2012) Honey bee health: the potential role of microbes, in D Sammataro and J Yoder, eds. (2012) Honey Bee Colony Health : Challenges and Sustainable Solutions. CRC Press.

[13] Yoder, J.A., Condon, M.R., Heydinger, D.J., Hedges, B.Z., Sammataro, D., Finley-Short, J.V., Hoffman, G.D., Olson, E. 2012. Fungicides reduce symbiotic fungi in bee bread and the beneficial fungi in colonies. In: Honey Bee Colony Health, ibid, p. 193-214.

[14] Olofsson, TC & A Vásquez (2008) Detection and identification of a novel lactic acid bacterial flora within the honey stomach of the honey bee Apis mellifera. Current Microbiology 57(4): 356-363.

Vásquez, A &TC Olofsson (2009) The lactic acid bacteria involved in the production of bee pollen and bee bread. Journal of Apicultural Research and Bee World 48(3): 189-195.

[15] https://www.youtube.com/watch?v=dQYY1WUyVD4

[16] Degrandi-Hoffman, G, et al (2009) The importance of microbes in nutrition and health of honey bee colonies (published in 3 parts). American bee Journal 149(6-8).

[17] Discussion introduced by Oldtimer on Beesource thread “Microbial Activity and Pollen Myth.”

Perhaps one of the easiest, if non scientific ways we can observe that bees use pollen that has not been stored and fermented, and any beekeeper can do this, is observing a newly hived swarm. The hive can be opened a few days after being hived and will have brand new comb with eggs and new larvae. The larvae are sitting in white royal jelly. This is despite that the hive may have virtually no pollen in storage, and if there is any pollen in cells it has been there such a brief time it is not even patted down.
To my non scientific head it is clear bees can create bee larvae food from perfectly fresh pollen.

[18] http://scientificbeekeeping.com/a-comparative-test-of-the-pollen-sub/

[19] Herbert, EW & H Shimanuki (1978) Chemical composition and nutritive value of bee-collected and bee-stored pollen. Apidologie 9: 33–40.

Loper (1980) Op cit.

[20] Fernandes-Da-Silva, PG & JE Serrão (2000) Nutritive value and apparent digestibility of bee-collected and bee-stored pollen in the stingless bee, Scaptotrigona postica Latr. (Hymenoptera, Apidae, Meliponini) Apidologie 31: 39–45.

[21] Martinson VG, Moy J, Moran NA (2012) Establishment of characteristic gut bacteria during development of the honey bee worker. Appl Environ Microbiol 78: 2830–2840.

[22] Martinson (2012) ibid.

[23] Snodgras, RE (1910) The Anatomy of the Honey Bee. USDA Technical Series, No. 18, Government Printing Office.

[24] Anderson, KE, et al (2011) An emerging paradigm of colony health: microbial balance of the honey bee and hive (Apis mellifera). Insect. Soc. 58: 431–444.