Tracheal mites attach themselves to the inside of a bee’s breathing tubes and feed on the bee’s blood. The bees that survive are usually so weak that they can’t maintain their hive.
“Infested bees become very lethargic,” said Cobey. “In really severe cases, the bees end up crawling in the grass because they’ve lost their ability to fly. They stop foraging and feeding their young so the population dwindles. They also develop secondary infections caused by bacteria or fungi. In that condition, they can’t defend their hive from invaders. The mites continue to spread because healthy bees from other hives invade these weakened colonies to steal honey, and they carry tracheal mites back with them.”
Since the 1980s, bees in the United States have begun to develop their own resistance -- slowly. Cobey said the process normally takes decades.
“What we’re trying to do is speed up the process of natural selection by breeding the bees that seem least affected by the mites,” said Cobey.
Cobey oversees about 200 hives on the Ohio State campus. As in the commercial beekeeping industry, each hive consists of a stack of wooden boxes that she and the other researchers expand as the population increases, and occasionally dismantle to study the interior conditions.
Since 1991, Cobey and her colleagues have been maintaining a special breed of bee they call the New World Carniolan (NWC). Through artificial insemination, they have been breeding queens and drones that appear to show mite resistance and high honey production. Twice a year, the researchers dissect a random sample of bees and search their tracheas for mites.
Cobey said that the selective breeding program is responsibl
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Contact: Susan Cobey
Cobey.1@osu.edu
(614) 292-7928
Ohio State University
20-Jan-1998