Imagine you had a mite the size of your fist attached to your back; that’s a Varroa mite to a honey bee.
These mites are called Varroa destructors, an external parasitic mite that attaches to honey bees, causing disease and weakening honey bees and their colonies. According to recent studies, feral honey bees in Ohio are adapting to fight back against these mites.
“Good news from the world of feral honey bees,” said Dwight Wells, president of the West Central Ohio Beekeepers Association and project manager of a feral honey bee project through Propolis Projects, LLC (Propolis). Propolis is an effort developed by the Levin Family Foundation and its mission is to combat the recent decline of pollinators in the Midwest and restore healthier honey bee populations in Ohio.
“The [feral honey bee project’s] results show that survivor feral honey bees are winning the war with Varroa,” said Wells. “[The feral honey bees] are gradually building the tolerance and chewing behavior to where the mites’ populations are very low.” Some of the feral honey bees will bite the legs or head off the mites, causing them to die.
Several organizations and experts are working together on this feral honey bee project to study the mite-biting behavior of feral honey bees in Ohio, including Wright Patterson Air Force Base (where Wells is beekeeper), Purdue University, Central State University, Penn State, The Ohio State University and others.
The project includes testing feral honey bees, not commercial or packaged honey bees. Feral colonies come from wild swarms, which were trapped, caught and kept as a stationary colony in bee boxes.
The project’s feral colonies are located throughout Ohio, including: 6 in Miami County; 30 in Logan County; 11 in Clark County; and 3 in northern Ohio, for a total of 50 feral colonies. The three feral colonies in a northern Ohio have kept the Varroa mites under a healthy level for 14 months, according to Wells. Varroa mites under 1 mite per 100 honey bees is considered a safe level for a colony. Some of the colonies are 1 Varroa mite per 400 honey bees, depending on the area of Ohio in which the colony is located.
Overall the chewing rate of the 50 colonies is about 60 percent, according to Wells. The percentage of mite-biting behavior by colony runs between 47 to 77 percent.
Four years ago, Wells and his team tested for chewing behavior on 10 feral colonies, and the chewing result was 40 percent, as compared to the 60 percent for the 50 colonies, “Indicating that the colony chewing behavior percentage is getting better over the years,” said Wells.
Wells began studying mite-biting behavior in feral honey bees in 2015, when he was working with the Heartland Honeybee Breeder Co-op out of Purdue University.
How do they test?
The Propolis team places screen bottom boards at the bottom of the honey beehive boxes. Beneathe the screen is a solid tray that catches mites that have been bitten. The screen keeps the honey bees from getting through, but allows the mites to fall through onto the tray beneath. They add vegetable oil on the tray so that mites cannot move. The hive boxes are placed on the screen bottom board all year.
“We take those mites and examine all those mites and determine what the percentage of chewing behavior is,” said Wells, adding that they use a microscope and a camera.
No one else is doing this type of research in the United States, according to Wells.
“[The bees] are getting better genetically. Their genes are being expressed better — evolving or adapting to become a natural enemy of the mites, just like they did in Asia many years ago,” said Wells. Asian honey bees have adapted the ability to groom the mites off their backs. They have had these mites for many years and have become more mite-resistant.
Propolis has another 150 colonies to test for mite-biting behavior, but Wells said they need warm weather in 2019 to test them.
Commercial honey bees
At Central State University (CSU), Dr. Hongmei Li-Byarlay, researcher within the College of Engineering, Science, Technology & Agriculture, is leading the university’s first apicultural program, emphasizing the importance of beekeeping and pollination in Ohio and the United States. Li-Byarlay helps lead the Propolis feral honey bee testing efforts.
Li-Byarlay did research on commercial honey bees, finding that their mite-biting behavior was between 3 and 10 percent. This is low compared to the feral honey bees.
The feral honey bees are stationary and, “don’t get mixed up with the ones out there in the Almond fields,” according to Wells.
In February and March, 2.4 million colonies are shipped to California to provide pollination to crops, such as Almond fields. Chemicals are used to treat the mites in these colonies, said Wells, adding that many of these honey bees often lack nutrition.
“Not sure where the commercial guys are going to go,” said Wells. He explained that Drones (male bees) that aren’t fed properly aren’t strong enough to penetrate the egg, and don’t have good, healthy sperm to reproduce.
“I don’t know where that industry is going to go in the next twenty years,” said Wells.
According to Wells, the 11 feral colonies in Clark County have not been chemically-treated to kill mites for five years and the bees are chewing and keeping a safe level.
“We collected Drones from the best percent of chewed mite colonies to harvest semen from,” said Wells, explaining that with 50 tested colonies, they have enough resources to do selection and insemination of queens, the mother of all the bees in the colony.
Wells added that feral honey bees in Pennsylvania are beginning to show adaptations similar to those bees in western Ohio. Wells traveled to Armstrong County, PA at the end of January to teach a group of 40 people how to trap and catch wild honey bee swarms. “[Pennsylvania beekeepers] will do the same thing Ohio is doing in a couple of years,” said Wells, adding that he is working with Penn State on this project.
The Ohio State University has 21 honey bee colonies at its research farm. This summer OSU will transition 3 acres into prairie habitat for honey bees.
For more information visit: www.propolisprojects.org