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Varroa mites attack honey bees by camouflaging their scent

Jun 4, 2015

Varroa mites, the most serious threat to honey bees worldwide, are infiltrating hives by smelling like bees.
Credit Zachary Huang / MSU

Honey bees are under attack from a lot of threats.

Researchers say varroa mites are the biggest threat. They suck blood from bees, and can kill entire colonies.

Zachary Huang is an associate professor at Michigan State University. He says these mites use a special skill to attack bee hives. They can change how they smell, so the bees don’t know they’re there. They can actually mimic the smell of a honey bee.

In a new study in the journal Biology Letters, he found the mites could change how they smell within days.

“Mites are able to change their surface chemicals, their smell, so that the host probably won’t as easily be able to pick them off, to detect them,” he explains.

In the study, Huang found the mites could quickly change their smell to mimic different species of bees. He says understanding how this chemical camouflage works might help researchers come up with new ways to get rid of the mites.

In a blog post, Huang explains why he wanted to investigate this:

I had in mind to see how far mites can go to change their surface chemicals — the chemicals that insects often use for recognition. Honey bees, for example use these chemicals to distinguish who is their hive mates. In the case of honey bee workers, it seems the smell is a combination of genetics (from father and mother) but also smells from the environment, forming a “Gestalt” of odor.

In the case of the notorious varroa mites, we know that they can change their surface chemicals to match the developmental stage of their hosts: a mite will smell more like a pupae if the host is at the pupae stage, and more like an adult bee when the bee is ready to emerge. I thought perhaps we can challenge mites to see if they could smell like a honey bee of an entirely different species? Nobody has done this before and this can be challenging.