Nutrition and Immunology of Honey Bees, with Rachael Bonoan
Disclaimer: This is the text of the pre-podcast transcript. This is a document that the interviewee and myself collaborate on and aren’t always very tidy in producing. But I think it’s better to publish it so that people can check it out and read instead of listen, if they so prefer.
How did you become interested in honey bees, their ecology, nutrition, and immunology?
As an undergraduate, I did research on social birds (zebra finches) and butterflies. I loved the fact that the birds were social but I also loved working with insects. So, I decided to apply to graduate school to work with social insects (ants, termites, bees, wasps). The honey bee lab (Starks Lab at Tufts University) was the best fit for me, I learned to how to keep bees, and I became enamored.
What exactly are nutritional ecology and ecological immunology?
Nutritional ecology is the cross-disciplinary study of how an organism’s nutritional requirements, foraging behavior, and nutrient utilization are affected by environmental factors. Ecological immunity is a similar cross-disciplinary field which focuses on how environmental factors affect health and the development of the immune system. In the case of honey bees, I am interested in how natural forage changes across seasons affect behavior and health.
Let’s discuss this idea briefly. In human immunology, the last thirty years or so have been full of important findings about the importance of environmental factors. Subtle differences in the environment, often unnoticed by individuals or communities, may have enormous impacts. For example, differences in bacteria in drinking water can lead to differences in the prevalence of certain diseases, specifically allergies and (it’s speculated) autoimmune diseases). Air pollution and pollutants in the food supply are another important example of this, having been linked to the rise in all kinds of diseases.
What’s become most interesting to me about most of these is that many are based in our social behaviors. People overeat at social occasions. They engage less in social activities that include exercise, whether it’s sports or going for a walk with someone. We’ve allowed many variables in our environments to change in such a way that they’re harming us, often without our recognizing it. I’ve begun to think of these as ecological traps, a concept Charles introduced me to the other month.
I’ve also begun to speculate that our social behaviors are often motivated to meet needs we’re unaware of — much like honey bee salt foraging. Recognizing these needs seems key to changing our behaviors mindfully, to meet our needs in a healthy way.
How does salt foraging fit into these interests and why is salt so important for honey bees?
That’s interesting — I do agree that when it comes to humans, there is some sort of ecological and/or evolutionary trap — we’re changing our environment so quickly, it’s hard for our biology to keep up. Even if we overeat or forget to exercise, we still survive long enough to raise our kids. There’s not much for natural selection to act on. Salt foraging in honey bees is a way in which honey bees deal with their changing environment. But, in the case of honey bees — and other pollinators, it’s imperative that they meet their nutritional demands — even in the face of a changing environment — in order to survive. Flowers are the main source of nutrients for honey bees: pollen provides proteins, fats, and trace minerals (or salts), nectar provides carbohydrates and trace minerals. Those “trace minerals” provided by flowers are likely not enough to sustain a whole honey bee hive and so, honey bees search for minerals in alternate sources. That’s where salt foraging comes in: beekeepers have noticed that honey bees tend to prefer dirty water over clean water. And recently, I found that dirty water is essentially vitamin water for bees. Honey bees search for minerals in water that their floral diet is lacking. So in the fall, when there isn’t a lot of magnesium and potassium in floral resources, honey bees search for those minerals in water. No matter the season, honey bees search for sodium in water. This is likely because most plants are wicked low in sodium content.
Minerals (or salts) are important for a variety of reasons: sodium and potassium are important for water and pH regulation, calcium is important for muscle movement, magnesium is a co-factor for various physiological processes.
What are the consequences of nutrient deprivation to honey bee hives?
Since a honey bee colony works as a superorganism (each individual is like a cell in an organism), improper individual nutrition can affect the hive as a whole.
Minerals and Vitamins:
It’s important to note that in the same historical period that people have begun to massively overeat, we’ve also dropped the content of micronutrients in our food, whether it’s vitamins or minerals. It seems like maybe we’re trying to find these micronutrients, which we’re now deficient in, the only way we know how.
Likewise, during this period we’ve experienced a dramatic rise in allergies and autoimmune diseases. Not only are these linked to pollution, which I mentioned above, but to changes in nutrition, and particularly to gut ecology.
Do we see changes in diseases, whether viral, bacterial, degenerative, or other in honey bees in situations of nutrient deprivation?
Well, I have found that visits to mineral solutions correlate with stronger honey bee hives (and by stronger hives, I mean more offspring and thus more bees). I should stress that my findings are correlational — we don’t know if a hive is strong because they visit minerals or the hive visited more minerals because they were strong — but there is a clear link between mineral availability and hive health. There hasn’t been much research done on micronutrient deprivation and honey bee disease, but past research shows that protein deprivation affects baseline immunity in honey bees. This coming summer, I will look at how protein deprivation affects honey bee immune response when the hive is challenged with a common disease.
Honey bee salt foraging behavior changes in accordance with levels of these nutrients in pollen or other food sources. Has this finding been proven in organisms? Can we extrapolate this finding to humans?
Yes, this behavior has been found across the animal kingdom: bats, elephants, moose, apes, monkeys, goats, butterflies, ants, sweat bees, etc. In fact, sweat bees get their common name from this behavior: they like to drink the sodium-rich sweat from livestock. And yes, these findings can be extrapolated to humans: in the 1980s, Dr. Derek Denton published a book called The Hunger for Salt. In his book, Dr. Denton compiles 20 years of salt-foraging studies ranging from humans to mountain goats. In wild animals, a lack of salt can compromise strength and speed. In humans, a serious lack of salt can lead to reduction in blood and fluid volume: a salt-deprived human is likely to feel lethargic, weak, and achey. Human salt cravings are apparent in pregnant women (who are eating for two!).
But when we speak about salt, it’s so important to discuss what we really mean. One of the fascinating things about salt is that it seems like humans can’t really tell the difference between sodium chloride, potassium chloride, or other salts or salt substitutes. When people are told to avoid salt for their blood pressure, it’s potentially depriving them of all these beneficial salts that are absent in our food. This only increases my suspicion that overeating is a desperate search to meet our needs for nutrients that we’ve edited out of the food supply. These changes have been made in ignorance (sometimes willful) of their consequences for our health.
Sodium chloride and potassium chloride are just two possible “salts” that people find at the grocery store — sodium chloride of course being “table salt” and potassium chloride being the most common “salt substitute” that people buy.
Salt means so much more than just sodium and potassium. Many different salts are necessary for human health and I’m sure bees — selenium, iodine, calcium, magnesium, just to name a few.
How much study has been done in bees regarding deficiencies of any of these single minerals?
(THERE HAS BEEN AN IODINE STUDY — HAVE TO FIND IT)
One of the prior research findings you discuss in your paper is that dietary diversity confers improved immunity and therefore fitness to honey bees. What are the possible mechanisms for this and how might they be extrapolated to humans?
It’s likely that honey bees can sense and achieve a balanced diet when given the option. If honey bees are raised on one type of food (or flower) that is deficient in a certain nutrient, they are unable to balance this deficiency with different food (or floral) sources. When searching for food for the hive, foragers can likely taste or smell the nutritional differences between food sources. In my rstudy, foraging bees seemed to sample salt solutions until they found one they liked where they stayed and drank. In humans, we call these cravings. We crave salt and sugar because evolutionarily, both were once hard to find. Dr. Stephen J. Simpson and David Raubenheimer discuss this in their book The Nature of Nutrition: A Unifying Framework from Animal Adaptation to Human Obesity. Salt and sugar are no longer as scarce as they once were but our cravings have yet to catch up.
We’ve seen the ability of animals to distinguish between foods that are nutrient deficient or nutrient rich in a wide range of tests. I’d say it’s safe to say that humans have the same mechanisms, though how we perceive or actually consciously distinguish between nutrient-dense and nutrient-poor foods, realizing of course that each person needs a different balance at any given moment.
This makes me think, again, of ecological traps. We can make any food salty with the addition of salts that aren’t found in nature, whether it’s table salt or salt substitute. But in nature, salty foods are almost always conferring important other nutrients than just sodium and chloride. Sea weeds are rich in iodine, fiber, and phytonutrients. Fish or shellfish are rich in all sorts of minerals and healthy fatty acids. Sweet foods include honey and fruits, which are rich in vitamins, minerals, and phytochemicals. So we’ve “hacked” — so to speak — our natural mechanisms for eating healthy.
Epidemiological studies have shown that “hard-water” confers immunological/fitness advantages to humans as well, hard water of course containing high quantities of calcium, magnesium, selenium, and other necessary cations. You mention salt and potassium in your study — what research has been done into other trace elements? (i.e. Boron, strontium, selenium, manganese, sulfur, iodine)
Honey bees raise more brood when adequately supplemented with minerals. Are there changes in honey bee behavior or biology that are observable other than brood success/number based on mineral intake?
Honey bees are a critical part of our food system. What changes do you think need to happen in the food system to protect honey bees and ensure that they thrive?
You’re absolutely right — bees are critical to nutrient-rich human food! We get most of our vitamins and minerals from fruits and vegetables that require insect pollinators. Also, most people don’t realize that meat indirectly relies on insect pollination as well. Livestock is fed alfalfa, which pollinated by bees. Unfortunately, there has been a staggering decline in pollinator health and without insect pollinators, it will be a lot harder for us humans to eat healthy. One of the biggest stressors for honey bees is that they are shipped from crop to crop depending on what’s in season. So, during almond season, a hive literally only has food from almond flowers, which we know are deficient in essential amino acids (i.e. proteins). To help honey bees — and other insect pollinators — thrive, monoculture crops should be supplemented with diverse wildflowers so that they have choices. These monocultures are also treated with pesticides so if bees are looking for minerals in dirty water in that monoculture, they’re likely going to find those minerals in pesticide run-off. Salt licks could be put out for bees as a safer “dirty water” alternative.
How can foodwise help honey bees and the people who study and work to protect them?
Plant diverse flowers for honey bees and other pollinators! Not only do insect pollinators need diverse plants for diverse nutrients but they need flowers throughout the year. Plant flowers with a range of bloom times. The Pollinator Partnership has an app called BeeSmart that is great for pollinator-aware gardeners. You put in your zip code, and which type of pollinator you’d like to help out (bees, butterflies, even birds and bats), and the app will tell you which flowers to plant, and when they bloom. Also, if you are going to treat your lawn or garden with pesticides, make sure to read to label so as to apply treatments correctly and affect the bee’s food as little as possible. And finally, support your local beekeepers and farmers!
If people want to learn more about your research, how can they find you/get in touch?
There are two main ways to reach me: my website and my twitter account. My website is www.rachaelebonoan.com and my twitter handle is @RachaelEBee. You can read the full article of the study we discussed today on my website!