Genetic discovery may help control varroa mites in bees

A gene linked to autism in humans and obsessive grooming in mice may help bees fight back against varroa mites, say scientists at Purdue University.

Within a bee colony, certain bees have the innate ability to thwart varroa mites by grooming or detecting the presence of mites.

In a paper published in Plos One, an online scientific journal, Greg Hunt, professor of behavioural genetics at Purdue, said it may be possible to select and breed bees that will go to war with mites to keep the parasites under control.

“Bees are fighting back. They’re getting rid of the mites themselves,” said Hunt. “We can select for these traits now, but it’s tedious. If we can identify the genes that influence these traits, we could develop better methods to screen for these genes and speed the process.”

Over the last two decades, North American beekeepers have struggled to protect their colonies from varroa mites. The parasites weaken honeybees and infect the bees with deadly viruses. In Canada, entomologists have blamed mites for the high colony losses in the latter half of the 2000s, when beekeepers in a number of provinces lost 30 to 40 percent of their colonies over the winter.

Entomologists have known for a while that bees do groom and remove mites from their bodies, but a minority of bees exhibit this trait.

The Purdue scientists looked for the genes linked to the grooming behaviour and isolated a region on one bee chromosome that contains 27 genes.

The researchers suspect a gene called Neurexin 1 may be responsible, which is associated with autism and schizophrenia in humans.

“It raises the possibility that the same gene might be influencing some behaviour in two very different species,” Hunt said.

Besides the grooming behaviour, Hunt and Purdue colleagues found that certain bees are able to detect when something is wrong in the hive. Somehow, possibly through smell, the bees know that mites are inside brood cells, which contain developing bees. The suspicious bees will crack open the cell and remove the infested material, thus defeating the mites in another fashion.

The scientists are also seeking the genes linked to that behaviour.