One evening, the plight of honeybees, including colony collapse disorder, was discussed at the family dinner table of Jeffrey Michel, MD, cardiologist. A young family member asked if maybe the honeybees were having heart attacks.
Bees are always busy, buzzing around constantly and working until they die.
Do bees even have hearts?
Cardiologist Jeffrey Michel, MD was familiar with Kounis syndrome, an acute myocardial infarction caused by bee stings. He wondered if colony collapse disorder could be the same condition in reverse, where bees have heart attacks due to human actions. That’s if bees even have hearts… he determined to find out and used taxonomy to do so. His findings were published at the National Center for Biotechnology Information (NCBI) on December 20, 2018.
In the remarkable categorizing system developed by Swedish scientist Carl Linaeus in the 1700s, humans and honeybees are animals. The animal branch divides into phylum, class, order, family, genus and species. The animal kingdom contains organisms called heterotrophs, which rely on external food sources for nourishment.
The honeybee was domesticated around 10,000 years ago during the agricultural revolution for the purpose of pollination. It is only one of roughly 20,000 species of bees, and wild bees are usually solitary with neither queen nor hive. All bees, unfortunately, are dealing with colony collapse disorder.
This unrelated 6-minute video Anatomy of a Bee by Objectivity was filmed at Oxford University Museum of Natural History. Bethany and Brady reveal some rare bee anatomy models in the final minute:
Almost every animal has a cardiovascular system. Carl Linnaeus categorized the honeybee in 1758. Honeybees belong to phylum Euarthropoda, class Insecta, order Hymenoptera, family Apidae, genus Apis Linnaeus and species Apis mellifera Linnaeus. All insects, as members of the class Arthropodia, have an “open” cardiovascular system.
Dr. Michel explains the honeybee cardiovascular system in great scientific detail. You can read his original article notes here. In short, the honeybee body is filled with extracellular fluid called hemolymph. Modern imaging of insect circulation reveals regular “heart rates” and measurable hemolymph flow as seen in other animals.
It seems hemolymph circulation is important, or else insects would hardly invest the energy and effort. Dr. Michel wondered if stopping the hemolymph flow in a honeybee might be equivalent to a human heart attack.
Hearts like a human heart with chambers and valves are found in vertebrate animals. Humans developed pesticides and chemicals, and recently developed the pesticide family known as neonicotinoids by modifying the chemical structure of nicotine. These are water soluble and are absorbed into plants, so this gave them tobacco plant-like resistance to insects. These compounds make their way into nectar that bees gather.
It has been noted by observers that the development and use of neonicotinoids has paralleled colony collapse disorder.
Why do tobacco plants make nicotine in the first place? Nicotine, like man made neonicotinoids, binds to acetylcholine receptors. In mammals, nicotinic acetylcholine receptors are located in cells of both the central nervous system and peripheral nervous system. These receptors are activated by acetylcholine but also bind and are activated by nicotine.
The binding is relatively weak in humans but in insects, nicotine binds strongly. In humans, nicotine-mediated activation of receptors increases neural transmission but in insects, receptors are blocked, causing loss of function. The nicotine or neonicotinoids cannot be broken down, and this prevents their clearance.
According to Dr. Michel, insect “hearts” are dependent on neural networks. Honeybee hearts could slow and even stop if poisoned by neonicotinoids. Loss of hemolymph circulation may play a role in the death of bees exposed to these agents.
It’s amazing to think that this quest for an answer, and the unique information it resulted in, all came about due to a curious child at Dr. Michel’s dinner table.