Managing Varroa and Tropilaelaps Mites in Your Apiary
Almost every beekeeper today is familiar with Varroa mites, external parasites of honey bees that to a large degree dictates how we manage colonies, no matter the size of our operation.
They were first detected in the United States in October 1987 in Florida. They rapidly spread across the country over the next two years. By 1995, the pest was documented in every state.
The Varroa mite is indigenous to Asia, where it’s a parasite of the Asian honey bee, Apis cerana.
In its native habitat, the mite doesn’t have a serious impact on the Asian honey bee because the bees have natural defenses that evolved over time.
However, when the Varroa mite reached Europe in the 1970s and subsequently North America, it had disastrous consequences for the European honey bee, Apis mellifera.
The Varroa mite is now considered a global threat to bees.
Australia was the only continent on the planet that didn’t have Varroa until they were detected there in June 2022 at the Port of Newcastle in New South Wales.
In response to the outbreak, Australia has tested more than 130,000 hives for the mite and destroyed more than 25,000.
However, some say that the time lag between when the mite arrives and when it becomes apparent to authorities makes it difficult to eradicate.
The initial strategy was to control the mite by euthanizing all hives discovered to be infested, but that plan was abandoned after the scale proved to be hopeless.
As of September 2023, Australia has abandoned efforts to eradicate the mite and is instead focusing on a plan to help beekeepers and other industries prepare and manage it.
This includes a national education program, training and requiring beekeepers to inspect their hives and report any detections.
Sadly, Varroa has now established itself on every inhabited continent on Earth.
When I began keeping bees, we talked about tracheal mites, Acarapis woodi. Although I was aware of them, Varroa were not all that big a deal at that time.
Tracheal mites are less than 0.2 millimeters in size and can only be seen with a microscope. These pests can be spread between hives and apiaries when bees drift between them or come from infested colonies.
Mated female mites leave the breathing tubes where they develop and attach themselves to the hairs of a passing bee, entering the bee’s trachea through the thoracic spiracles.
Tracheal mites feed on bee hemolymph (fluid of the circulatory and lymphatic system similar to blood). In beekeeping today, tracheal mite levels are statistically insignificant.
Sam Ramsey, a nationally recognized speaker and assistant professor of ecology and evolutionary biology at the University of Colorado, Boulder, is the leading researcher of mites.
He received his B.S. in entomology from Cornell University and his Ph.D. in entomology from the University of Maryland, College Park. He was our speaker at the fall conference a few years ago.
There are now reports that Tropilaelaps mites have established populations in Ukraine. Dr. Ramsey warns that their presence is the biggest wake-up call to the rest of the world about this parasite.
Ukraine exports bees to Canada, so North America might not be too far behind.
Tropilaelaps are both deadlier and harder to kill than Varroa. When the mites reached India, entomologists estimated that they killed between 50% and 100% of the colonies they infested.
A similar death toll in the U.S. would have a devastating impact on not only beekeeping, but also on agriculture.
Our industry struggles to manage Varroa, and we collectively agree that we are nowhere near ready to deal with this new pest.
Much like Australia is learning to deal with Varroa, the United States will almost assuredly be dealing with Tropilaelaps in the future.
One of the criticisms that SB 1198 has received is a perceived vagueness in some of the language.
If this law passes, it will be further defined by regulation after its passing. The vagueness is intended to give the state some ability to manage Tropilaelaps and other yet-to-be-determined pests when they arrive.
