An international research team has some good news for the struggling honeybee, and the millions of people who depend on them to pollinate crops and other plants.
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These valuable pollinators have faced widespread colony losses over the past decade, largely due to the spread of a predatory mite called Varroa destructor. But the bees might not be in as dire a state as it seems, according to research recently published in Nature Communications.
Researchers found a population of wild bees from around Ithaca, New York, which is as strong today as ever, despite the mites invading the region in the mid-1990s.
"They took a hit, but they recovered," said Alexander Mikheyev, a professor at the Okinawa Institute of Science and Technology Graduate University (OIST) in Japan and lead paper author. "The population appears to have developed genetic resistance."
Mikheyev and his collaborators at OIST and Cornell University studied the population genetics of the wild colony by comparing the DNA of specimens collected in 1977 with bees collected from the same forest in 2010. To conduct the study, they developed a new DNA analysis tool that works especially well for degraded DNA stored in museum samples.
Such a study is extremely rare, especially with bees. Few people collect them, and even fewer collect in a way that is good enough for a population level study. Luckily, Cornell Professor Tom Seeley worked in this area during his Ph.D., and deposited his samples in the Cornell University Insect Collection. This is the first time scientists have been able to observe genome-wide changes after a specific event like the mite invasion.
First, mitochondrial DNA, the genetic material stored in cells" power plants, changed significantly from the older generation to the newer generation. Then, one of the most interesting changes in the bee population was in a gene related to a dopamine receptor known to control aversion learning. Another study has suggested this receptor is involved with bees grooming themselves to get rid of the mites by chewing them up.
The researchers also found many changes in genes associated with development. Mites reproduce and feed on the bee during the bees" larval stage, so the researchers hypothesize that bees evolved to disrupt that process. Also, there were physical changes " today's bees are smaller than the older bees and their wing shape is different. ■
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