The Buzz on Bee Toxicology
I have an affinity for bees. I came by it honestly: my grandfather was a beekeeper. Upon his death decades ago, I was allowed to take a few small keepsakes from his home; one of my choices was his beekeeping book, “The Hive and the Honey Bee, Edited by Roy A. Grout.” His copy was printed in 1954, but the history of the book dates a 101 years earlier (authored by Langstroth) and continued through 2015 (edited by Graham). Unfortunately, I only love bees from afar: the affinity skipped a generation (getting stung so many times as a child quelled my father’s enthusiasm), and my significant other is extremely phobic about small yellow-and-black flying things. But I love to learn about bees.
Worker bees become foragers towards the end of their lifecycle because it’s just too dangerous for the youngsters. Despite being the size of a raisin, these ladies (worker bees are all females) fly for miles to bring home the groceries. When they find a food source, they have to collect as much food as they can, find their way home, and, once home, tell the other workers where to go for more using a special dance. Young workers stay home and do other important tasks: cleaning the hive, rearing young, making and recycling wax, drying nectar into honey, and making the pollen into bee bread. The latter they do by mixing the pollen with microorganisms like bacteria, protozoa, and fungi, and then letting it ferment. Bee bread is like bee sauerkraut (or, if you like it spicy, bee kimchee), but super nutritious.
Honeybees are literally an economic force of nature. Sure, honeybees produce $387 million-worth of honey each year in the U.S. alone, but that’s nothing compared to the almost $12 billion economic benefit domestic bees provide to U.S. farmers through pollination services. Worldwide, honeybee pollination efforts add-up to more than $200 billion U.S. dollars per year. We owe a lot to critters smaller than my fingernails! Of course, domestic honeybees aren’t the only pollinators that provide for our fruit and vegetable needs. We also rely on wild bees, butterflies, other insect species, birds, and bats as pollinators, many of which are threatened or endangered.
Honeybees pollinate crops across the U.S.: the hives of bees that pollinate orange groves in Florida could be the same ones pollinating blueberries in Maine, cherries in Washington, almonds in southern California, apples in Michigan, and the sunflowers in my neighborhood in Upstate New York. Imagine being packed into crates and hurtling across the country at 70 MPH on the back of an open flatbed! Life on the road is stressful: veterinarians know that when you ship animals this way, they are likely to get sick by the time they reach their destination. The resulting disease complex in cattle is called “shipping fever.” Bees also get shipping fever, and travel stress makes them more likely to succumb to disease and environmental toxicants.
Alas, if we’d been better stewards of the earth and her pollinators, we would not need them to keep on truckin’.
What do traveling bees eat? On my last road trip, failing to locate a health food store on the Interstate, I ate a lot of junk food. Bees, too, can get a suboptimal diet on the road. Modern farming uses monoculture: vast fields of the same crop that go on for acres and acres. The benefit of monoculture is easy automation, making it efficient and cost-effective. The drawback is that it works better for some crops than others, and disease can spread rapidly. Corn, for example, is easy to automate, and an enormous amount of the modern American diet is derived from inexpensive corn, corn products, corn syrup, and meat from animals that eat corn, but the excess of corn products limits the nutritional diversity that many people would otherwise enjoy. Pests and diseases can spread in plants (or people) that are crowded together - that’s why Covid-19 spread through big cities first, right? And, for bees, monoculture means extreme dietary restriction. We are healthier when we eat a balanced diet: citrus for vitamin C, greens for vitamin K and iron, legumes for protein, etc. Why would bees be any different? The nutritional content of the pollen and nectar varies between types of plant, so pollinating single species is not nutritionally sound.
But that’s not what I wanted to tell you about.
I wanted to tell you about bee toxicology. As a veterinarian and toxicologist, I knew that things like stress and poor nutrition can make animals more susceptible to environmental toxicants; this couldn’t be more true for bees. As a student of public health, I know that tiny doses of certain environmental contaminants can have lifelong detrimental effects in people; but what about bees?
The first thing most veterinarians think about when I say “bee toxicology” is insecticides. Insecticides applied in the wrong place at the wrong time can kill entire hives of bees, but that isn’t the end of the story. Remember when I mentioned how modern agriculture relies on monoculture? And that crowding the same species of plants together can lead to increased risk of pests and diseases? That is a major reason our modern agriculture is reliant on insecticides and other pesticides. Some products can be sprayed on plants at times when they aren’t flowering, to avoid exposing pollinators. Unfortunately, some pesticides hang around a long time, like DDT which was outlawed in the U.S. in the 1970s. DDT built up in the environment and food chain and nearly drove our national symbol, the bald eagle, out of existence. You can still find DDT-related chemicals in bee hives, because wild bees recycle the same wax for many decades.
What about modern insecticides? You may have heard of neonicotinoid insecticides like fipronil, clothianidin, and many others. “Neonics” don’t usually kill bees outright, although they certainly can. Neonics are “systemic insecticides.” This means that they can be put directly on the seed or in the soil, and then circulate through the plant as it grows. Consequently, neonics are found in nectar and pollen. If you buy nursery plants, keep an eye out for “pest protected” on the label, which means the plant contains systemic insecticide.
Worker bees are only exposed to small doses of neonics when they pollinate a flower or sip nectar. But they, and hive-mates and larvae (baby bees), are exposed daily to contaminated honey, bee bread, and the wax where neonics can be sequestered for a long time, exposing future generations. What does constant exposure to low doses of neurotoxic neonics do to an animal that must fly great distances to locate food, find her way home, and then communicate intricate instructions to her peers? Probably nothing good. Neonics are also believed to affect the development of larvae and resistance to some diseases.
Spinosad is another systemic insecticide and is made by microbes. Spinosad is more insidious than neonics because it’s considered “organic.” Even organic farms may not be safe for our bee friends! Then there are all kinds of pesticides besides insecticides: there are fungicides, herbicides, and even antibiotics. These may not have a direct physiologic effect on bees, but bees have microbes in their digestive systems, just like us, that are needed to digest food and absorb nutrients. Also, remember bee bread? It requires fungi, protozoans, and bacteria. If the ingredients are full of fungicides, herbicides, and antibiotics, what happens to the final product?
What can we do to protect our honeybees and other pollinators? Please support your local pollinators! Consider buying honey as a public service! Second, use integrative pest management (IPM) in your garden and avoid chemical pesticides. Avoid seeds and plants with systemic insecticides. Consider IPM and polyculture for larger scale agriculture. Eat a diverse diet with lots of fruits and vegetables, and, next time you see them, give your local apiarist (beekeeper) a (socially distant) fist bump for filling your plate!
Dr. Karyn Bischoff is the veterinary toxicologist for New York State and the Cornell University College of Veterinary Medicine, as well as a Masters of Public Health student at Cornell. Karyn works on improving our understanding of the human, animal, and environmental relationship, and is interested in socioeconomic drivers of human-wildlife conflict and wildlife poisoning. Her research interests also include examining heavy metals in wildlife, domestic animals, and the food chain, and the use of selenium and vitamin E as antioxidants in domestic animals and wildlife.