By KEVIN WALKER
Michigan Correspondent
 
LANSING, Mich. — There’s a lot of information out there about honeybee deaths, but not a lot of answers; that’s how Michael Hansen, Michigan’s state apiarist, put it last week.

“There’s been a pretty big die-off nationally,” he said. “We’ve had, over the past three to four years, a 30 percent loss of bee colonies over the winter. That’s the kind of struggle beekeepers are going through.”

Hansen said a number of factors are contributing to the large losses: these include varroa mites, tracheal mites, viruses, microspiridians and pesticides. “I myself believe that the varroa mite was the major problem,” he said.

He described the varroa mite, an external parasite that lives on honeybees, as a vector that helps to spread around and magnify the different problems bees have been having. Varroa mites were not present in U.S. honey bee colonies until about 25 years ago.
Hansen described colony collapse disorder (CCD), a phenomenon where much of a colony disappears from the colony, as a mixture of problems. “CCD has hit the Michigan beekeeper,” he said. “It’s a challenge, where we see it. CCD seems to be a special term for ‘we’re not sure how they died.’”

As part of a recent presentation to the Michigan Agriculture Commission, Hansen pointed out that Canadian beekeepers often wrap their colonies or keep them inside buildings over the winter, and yet have experienced similar losses to their counterparts in the United States. Those beekeepers are reporting they are finding many varroa mites in with the dead bees.

“Six to eight percent of losses can truly be blamed on CCD in the U.S.,” Hansen said.

In a study published this month in the Public Library of Science One journal – an open access online science magazine – scientists from Pennsylvania State University seem to point the finger at pesticides as one possible cause of CCD. They found 98 pesticides in bee pollen samples they collected from colonies in Florida and elsewhere.

Their findings represent “a remarkably high level for toxicants in the (bee) brood and adult food of this primary pollinator.” Yet elsewhere in the study the authors write, “(It) seems to us that it is far too early to attempt to link or to dismiss pesticide impacts with CCD.”

Hansen said that there are some scientists who come from a “pollinator perspective” and may be against the use of pesticides in general.

“You’ll always have arguments against pesticides because there are always going to be people who just don’t believe in using them,” he said.

He added that it’s not possible to eliminate pesticide residues in beehives because honeybees can forage for nectar up to two miles from where the colonies are placed. Even if an orchard hasn’t been sprayed with pesticides recently, bees may fly to a neighboring field that has been sprayed and gather nectar from those plants, bringing pesticide residues back to the colony.

“I agree that bee die-offs are more complicated than just pesticides,” said Jeff Pettis, a bee researcher at the USDA and a study co-author.