A Varroa mite on a honey bee. Photo by Alexander Wild. www.alexanderwild.com.

The parasites were originally found on Asian honey bees (Apis cerana), but later began infesting and killing European honey bees (Apis mellifera). The new study shows that they were able to switch hosts by switching their scents, a form of chemical camouflage.

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

The stealthy mites are able to smell like bees, and they can emit the specific scents of small, individual colonies. The codes in which they communicate are hydrocarbons, the simplest of organic compounds. By tweaking the proportions of these chemical colognes, the mites give off the correct scents to fool their hosts.

“They are essentially getting through the door and reaching the inner sanctum by using bees’ own complex communication codes against them,” Huang said.

Huang and his team showed that Varroa mites are able to change their surface chemicals to mimic an entirely different species of honey bee. Further, they also revealed that the mites were able to make these changes rather quickly — adapting in days rather than evolving over generations.

“Our study challenged the mites’ ability to modify their hydrocarbons,” Huang said. “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.”

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– Varroa destructor changes its cuticular hydrocarbons to mimic new hosts