New research shows Varroa mites, which are the largest threat to dwindling honeybee populations across the globe, are able to invade hives because they smell like the bees themselves.
These parasites were first spotted on Asian honeybees, but have now started infesting European populations, Michigan State University reported.
"The mites from Asian honeybees, or the original host, are more efficient in mimicking both Asian and European honeybees," said Zachary Huang, MSU entomologist and one of the papers' lead authors. "This remarkable adaptability may explain their relatively recent host shift from Asian to European honeybees."
In order to fool the honeybees, the mites must mimic their scent "spot-on." In bee hives, tens of thousands of bees are divided by sophisticated caste systems, and the invaders must be able to fool the entire colony in order to gain entrance. The mites have the ability to "smell" the bees and mimic the distinctive scents of individual colonies.
"They are essentially getting through the door and reaching the inner sanctum by using bees' own complex communication codes against them," Huang said.
These codes are created with hydrocarbons, and by tweaking the properties of these chemicals the mites are able to give off the appropriate scent, allowing them to enter bee colonies unnoticed. The mites proved to have the ability to completely adaptapt their chemical signatures to a completely different species of honeybee in a matter of days.
"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."
The findings were published in a recent edition of the journal Biology Letters.