Chemical camouflage (continued from last month)
Chemical camouflage
This new study shows that Varroa mites were able to switch honey bee hosts by switching their scents—a form of chemical camouflage.
For chemical camouflage we think of squid and chameleons with their colour-changing camouflage. Sex pheromones used in mating disruption of codling moth and Oriental fruit moth are well known.
However, fooling socially sophisticated insects, such as honeybees, requires the faux scents to be incredibly accurate.
This is 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 not only by being able to smell like bees, but also by effectively emitting the specific scents of small, individual colonies.
“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 codes in which the mites 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 and his team showed that Varroa mites are able to change their surface chemicals to mimic an entirely different species of honey bee.
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.”
See this article in Tree Fruit July 2015
