Wintergreen Bees 9/18/19

A true story by Richard Bleil

This is the story of bees and chemicals, but, no, I’m not going to talk about the pesticides that have brought the bees to the brink of extinction that, by the way, would also result in our own extinction. No, instead, this is a curious little tale about a research project a student of mine wanted to do.

See, she owned a bee farm. As she approached her senior year, she approached me because she needed a capstone project. Her idea was a wonderful cross disciplinary chemistry and biology project, but, sadly, the politics of the institution were, oh, let’s say “problematic”. None the less, we got started, and found some interesting things.

Her bees were being attacked by mites. The mites attach to the bee’s legs and feed on their blood, eventually killing the bees and, if left unchecked, will spread to and kill the entire hive. As it turns out, oil of wintergreen, the active ingredient of wintergreen flavored candies (which I love) is a natural defense against these mites. See. oil of wintergreen, as it turns out, is toxic. Now don’t give up your candies because the amount of oil of wintergreen you’d need to eat to begin to see the negative effects is, well, you just would never do it. But, take an insect as small as a bee, then take an insect small enough to live on the leg of that insect, and the amount of oil of wintergreen necessary to kill that itty bitty mite (“itty bitty” is a technical term from the field of biology) is small. Apparently all you need to do is put a bit of oil of wintergreen into the hive’s drinking water, and it kills the mites.

The student had a very interesting question. Does the oil of wintergreen kill the mites because it gets ON the bee’s legs, or because it gets IN the bee’s blood. But, oil of wintergreen is a volatile chemical, meaning it quickly and easily evaporates. This is why you can smell it so easily. So we needed a test that could be performed in the field, because if we sent the bees off to a lab somewhere, we’d probably loose too much of the oil. The ideal instrument (GC/MS for any chemists reading this) is, frankly, just too big to be portable. A visible light spectrophotometer, however, can be small, battery powered and would be perfect for field work. A visible light spectrophotometer measures the amount of light a solution absorbs in the visible light spectrum (red, orange, yellow, green, blue, indigo and violet light). Unfortunately, oil of wintergreen is a clear, colorless liquid and therefore does not absorb in the visible light spectrum.

The beauty of being a theoretical chemist is that it allows one to think across disciplines. So, I took a look at the structure of methylsalicylate, the technical name for oil of wintergreen, and I realized it looked like a chelating agent. Chelation is a special kind of chemical bond, where an organic with just the right structure and properties can bond to a metal. You might have heard of “chelation therapy”, although by this I mean the legitimate medical treatment as opposed to the new age holistic treatment. This is the treatment used to help purge heavy metals from the body by basically wrapping the metal ions up in an organic molecule, and when the body gets rid of this organic compound that doesn’t belong in the body, the molecule drags the heavy metal with it. If, indeed, it could form a chelate, though, we needed to find the right metal ion.

Then, along came rust.

The iron ion, as it turns out, is exactly the metal ion we were looking for, and the results were astounding! See, because of the hydration sphere (water surrounding the iron), it is orange. This absorbs light somewhere around 620 nm. But, methylsalicylate bonds with the iron ion, basically dislodging the water molecules, and the color of the iron changes from orange to purple, which absorbs around 420 nm. The color change was so stark, so astounding, and so beautiful that I could never forget it. This purple color was the key to the field test; the spectrophotometer can measure exactly the amount of light absorbed at 420 nm so precisely that it might not even be visible to the naked eye. And just like that, we had our field test.

So, where did the oil of wintergreen end up, on the bee’s fur or in the bee’s blood? Well, I have some bad news there. As it turns out, the politics of the college, namely a petty biology professor who was the student’s adviser, wouldn’t allow the student to perform the test because she didn’t consider it to be “biology”.

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