Study Suggests Modern Beekeeping Gives Varroa Mites Ideal Conditions to Spread

As the managed honey bee industry continues to grapple with significant annual colony losses, the Varroa destructor mite is emerging as the leading culprit. And, it turns out, the very nature of modern beekeeping may be giving the parasite the exact conditions it needs to spread nearly beyond control. In an article recently published in the Entomological Society of America’s Environmental Entomology, researchers argue that the Varroa mite has “co-opted” several honeybee behaviors to its own benefit, allowing it to disperse widely even though the mite itself is not a highly mobile insect. The mite’s ability to hitchhike on wandering bees, the infections it transmits to bees, and the density of colonies in managed beekeeping settings, make for a deadly combination.“Beekeepers need to rethink Varroa control and treat Varroa as a migratory pest,” says Gloria DeGrandi-Hoffman, Ph.D., research leader and location coordinator at the USDA-Agricultural Research Service’s Carl Hayden Bee Research Center in Tucson, AZ, and lead author of the research.In the wild, bee colonies tend to survive despite Varroa infestations, and colonies are usually located far enough apart to prevent mites from hitching rides to other colonies on foraging bees. Wild bee colonies’ natural habit of periodically swarming — when the colony grows large enough that a portion of its bees splinter off to create a new colony elsewhere — also serves as a mechanism for thinning out the density of mite infestations and their associated pathogens. In managed honeybee settings, though, these dynamics are disrupted, DeGrandi-Hoffman says. Colonies are kept in close proximity, and swarming is prevented.