Combating the Varroa Destructor Mite

Outside the beekeeping world, the words "Varroa destructor" do not cause the same fear as in someone who maintains bee colonies. This bug is one of the main culprits responsible for causing massive declines in worldwide honeybee populations. This past summer I had the opportunity, through the Fort Lewis College Chemistry department, to conduct innovative research on combating this pest.

The Varroa mite kills bees by sucking hemolymph from the bees’ blood; in essence they are small vampires.  It takes just 1,000 mites to kill a colony of 50,000 bees. Finding new ways to eradicate the Varroa mite is essential, as they have become immune to some insecticides already. The most popular method to combat a mite infestation is treating small slats with the volatile molecule Thymol, which acts as a pesticide to certain species of bugs, the mite included. Thymol is the active ingredient in the spice thyme, and it’s weird to think of something you use to flavor food as something that’s also used to kill bugs, but thymol is remarkable in that it has both medicinal and pesticidal properties.

Dr. Bill Collins, the professor in whose lab I worked, is an avid beekeeper. He noticed the main problem with using the current method of thymol slats to kill the Varroa mite is controlling dosage. If the weather is hot, more thymol is released from the slats and kills more mites, but if the weather is cooler less thymol is released and the mites could develop resistance. In addition, if there is a mite outbreak during honey production season, the honey might end up tasting like Vick’s Vaporub if you try to control it, which is the smell of the thymol molecule.

Dr. Collins formulated a way to synthetically add a thymol molecule onto a sugar molecule.  In the spring, when beekeepers feed their colonies sugar water to begin the summer season, they would be ingesting the non-active form of the thymol as well as the sugar. During metabolic activity the bond between the sugar and the thymol will break and the bees will become immune to the Varroa mite. If there is an infestation, when a mite tries to suck the blood from a bee they would be killed by the thymol in the bee’s system.

Research is ongoing, but the success of these ideas could mean a breakthrough in the way honey bees are treated for this small pest. Since the value of bee pollination and honey products in the United States alone is estimated around $16 billion, the success of this research would be a windfall in protecting the health of bees across the country and beyond.