Updated: Oct 5
The idea of probiotics for honey bees has only been around for a few years. As a novel idea, it generates a lot of questions. Many of these questions surround the concept of the gut microbiome.
Seeding the Gut
I like to think of microbiomes as gardens with many varieties of plants. The gut microbiome is a “garden” of bacteria planted in the gut. As with other communities, a microbiome forms, changes, and can be disrupted to the point of destruction. We now know that the newly emerged worker bees start out with no gut microbiome. They acquire it from the hive environment and from other bees. Interactions such as trophallaxis and cleaning the cells are critical because they introduce bacteria to the young bee’s digestive system. In other words, these interactions “plant the garden.” Without a source of bacteria (for example, when honey bees are reared in a lab), the young bees lack the characteristic microbiome.
Motta et al., “Prospects for probiotics in social bees,” ask: Can the bacteria be grown outside the hive? Their research demonstrates that culturing and feeding seven strains of native bee gut bacteria (Snodgrassella alvi, Gilliamella apicola, Gilliamella apis, Lactobacillus melliventris, Bombilactobacillus mellis, and Bifidobacterium asteroides) does just that. Researchers found that these bacteria, fed to young adult bees, populate the guts of newly emerged worker bees. In other words, they successfully plant a garden with the selected seeds.
One can think of the honey bee gut bacteria filling the gut of the newly emerged workers, like cereal filling a bowl. Without a source of these bacteria, “the bowl” will stay empty. The cereal can come from different sources. In an experiment by Motta et al., the scientists cultured the gut bacteria first and then fed them to the bees.
But can “the bowl” be filled with any cereal? While the seven native gut bacteria live in the honey bee gut, there is no consensus on whether they are beneficial to the honey bee host. “Although promising, establishment does not imply efficacy in promoting host health, and the benefits of native bee gut strains remain untested at the hive level,” cautions the article. Unexpectedly, the authors endorse genetically engineering these native gut bacteria to perform additional functions and express new traits. While this sounds very far-fetched, this can ultimately bring a new approach to protecting honey bee health. Such genetically engineered bacteria can be a permanent part of the microbiome if introduced. Three out of four authors hold a U.S. patent involving the use of genetically manipulated native bee gut bacteria as probiotics to improve health.
Probiotics with Benefits However, it is important to add that a probiotic does not need to be genetically engineered to be effective. The work of Motta et al. showed that a commercial probiotic (ProDFM from Mann Lake) did not colonize the gut of newly emerged worker bees. Note: Motta et al. did not test in their study on the original honey bee probiotic, SuperDFM-HoneyBee (Strong Microbials Inc., now available from Dadant).
Sir Robert Baden-Powell, the founder of the Boy Scouts, told scouts to “try to leave this world a little better than you found it” in his last message. This is how I think about probiotics, too. Probiotics may pass the digestive tract and not become a permanent part of a microbiome. This transient nature of a probiotic does not impair its usefulness. The scientific consensus is that probiotics can exert independent health benefits outside of colonization. These health benefits include functions such as digesting or detoxifying diet compounds. For example, microbial metabolism of nectar metabolites provides protection from parasites.
And looking at these benefits, are a lot of new questions. Simply said, bacteria benefit the gut by “leaving it a better place than they found it."