Mites fool honeybees with chemical ‘cologne’

Varroa mites "are essentially getting through the door and reaching the inner sanctum by using bees' own complex communication codes against them," says Zachary Huang. (Credit: Zachary Huang)

Varroa mites, the most serious threat to honeybees worldwide, are infiltrating hives by smelling like bees.

A new study in Biology Letters shows that being able to smell like their hostess reduces the chance that the parasite is found and killed.


“The mites from Asian honeybees, or the original host, are more efficient in mimicking both Asian and European honeybees,” says Zachary Huang, an entomologist at Michigan State University and one of the papers’ lead authors. “This remarkable adaptability may explain their relatively recent host shift from Asian to European honeybees.”

Chemical camo

Chemical camouflage isn’t a new weapon in insects’ arsenals. Bolas spiders, for example, emit not one but three chemicals to emulate a sex pheromone to attract moths to eat. However, fooling socially sophisticated insects, such as honeybees, requires the faux scents to be spot-on.

That’s because the complex society of bees comprises tens of thousands of individuals divided by a sophisticated caste system. So, the mites aren’t simply tricking a solitary bee collecting pollen from a flower; they’re fooling an entire society. The stealthy mites do this by not only by being able to smell like bees, but also by effectively emitting the specific scents of small, individual colonies.


Hydrocarbon changes


Specifically, it’s the cuticular hydrocarbons—compounds released from hair-shaft glands—that emit scents that differentiate queens from fertile and infertile workers; it’s the smell that invokes acceptance or triggers aggression.



“Our study challenged the mites’ ability to modify their hydrocarbons,” Huang says. “Conversely, bees are adapting to detect these invaders. Our results give a clear illustration of an arms race between the parasites and the host bees based on chemical mimicry and its detection.”

Additional researchers contributing to this study include scientists from the French National Institute for Agriculture Research, Honeybee Research Institute (China), and the Research Institute for the Biology of Insect (University of Tours, France).

Michigan State’s AgBioResearch contributes support for Huang’s work.

Source: Michigan State University