“Bees are attracted to rotting logs specifically for their immunological benefit. It’s part of their host defense of their immunity…and allow them to be better pollinators.” – Paul Stamets
Fungi range from deadly to delicious and some, like yeast, have for centuries played a critical role in our cuisine. Only in recent decades however have we begun to understand the ecological role that mushrooms and other fungi play and to use these species as tools for environmental stewardship. Mycoremediation is the practice of using fungi to remove contaminants from the environment, which is closely related to mycofiltration, which uses mycelium mats as biological filters. Mycorestoration is the idea that fungi can help improve the health of the environment by filtering water, helping plants grow, and controlling insect pests.
These terms were coined by a mycologist named Paul Stamets – and now he’s working on this question: What if mushrooms could save the honeybee (Apis mellifera)?
The basis of this question comes from his observations of the natural world. Several years ago, he observed a bear scratch on a tree. He knew that would be an entry point for polypore mushrooms – and when he returned two years later, a red belted polypore (Fomitopsis pinicola) was growing from the scratch. Red belted polypores are especially active in breaking down a variety of toxins, including pesticides, herbicides, and fungicides.
But how does this connect to bees? First, many polypores grow on birch trees. Bees go to scratched trees of willows, birch, and firs – to sip on sap and collect resins. That isn’t all: Stamets also remembers cultivating the King Stropharia in his garden decades ago, in a mycelium patch that was a foot thick (for mycofiltration to control E. coli in the water outflow of his property). While working in his garden one morning, he saw his bees had moved aside woodchips and were drinking the nectar exuded from the exposed mycelium.
It’s not as simple as bees simply seeking nectar where they can find it – although for those of us not well-versed in bee health, it may seem that way. It’s important to know that healthy honey and bee bread (pollen that has been packed into empty comb, mixed with nectar and digestive fluids, and then sealed with a smidge of honey) contain a polyphenol called p-coumaric acid.
Humans are fortunate in that p-coumaric acid is found in many edible plants, including peanuts, navy beans, tomatoes, carrots, and garlic, as well as wines and vinegar. Bees have more limited resources for getting p-coumaric acid. P-coumaric acid from pollen and fungal compounds is a component of honey and activates an important enzyme used by all animals for detoxification, cytochrome P450.
Honeybees have about 47 genes that control cytochrome P450 enzymes, which is many fewer than most insects, and research suggests that the low number of these, and similar, detoxifying genes may limit their ability to metabolize multiple toxins simultaneously.
But what if, as Stamets has posited, compounds from polypores (and other mushrooms) could be used to manage bee populations as a means of regulating immunity and detoxification pathways? That’s what his most recent experiments seek to find out.
He partnered with an entomologist at Washington State University, Dr. Steve Sheppard, and together they formed a research initiative, the goal of which is to reverse the declines in global bee population. In experiments last year, the pair placed Host Defense® mushroom extracts in the feed water of 300 sets of bees. They found that bees who consumed this water demonstrated a 75% reduction in their viral load. Results of other mushroom extracts showed a significant reduction in instances of Deformed Wing Virus, and increased honeybee longevity. Field tests will take place beginning this summer and are currently slated to last through summer 2017.
Stamets and Sheppard aren’t the only ones noticing the connection between bees and fungi. Last year, Cristiano Menezes, of the Brazilian Agricultural Research Corporation, published a paper on his observations of the Brazilian stingless bee (Scaptotrigona depilis) “farming” a fungus in the genus Monascus. Larvae eat this fungus and it is integral to their survival –those who don’t have access to it survive only 8% of the time. When bees leave their current hive to create a new one, they take some of the building material from the old hive with them – and by extension, take some of this fungus.
In 2012, researchers noted that a strain of Metarhizium anisopliae caused a high rate of morality in varroa mites (connected to Colony Collapse Disorder) with a relatively low rate of mortality for bees. Stamets and Sheppard are using this research on Metarhisium anisopliae in several experiments to determine the efficacy of building a beehive from fungus as a way of fighting off the varroa mite.
In one of these experiments, they have constructed a beehive with panels made of compressed sawdust that has been mixed with the mycelium of the Metarhizium anisopliae fungus. The bees, doing their bee thing, will naturally spread the spores throughout the hive. In another experiment, the two are placing pieces of cardboard impregnated with the mycelium into standard bee boxes. The thought is that the bees, who dislike clutter, will tear the cardboard apart to get rid of it – and in the process will dust bees and mites with the spores.
This research could have major implications for reversing the decline of the honeybee – and for the way that we interact with fungi – including, perhaps, the intentional cultivation of a variety of fungi and the trees that support polypores – going forward. To learn more, watch Paul Stamet’s 2014 TED talk and look for more blogs about pollinators coming soon!
June 20-26, 2016 is National Pollinator Week. National Pollinator Week began nine years ago, after the US Senate approved and designated a week in June to be focused on pollinator awareness. This marked an important acknowledgement of declining pollinator populations. It is part of the National Strategy to Support the Health of Honey Bees and Other Pollinators.