OREGON STATE UNIVERSITY

Genetics no panacea for honey bee crisis

12/18/1996

CORVALLIS - Commercial beekeepers are kidding themselves if they think that controlled genetic breeding will provide a solution anytime soon to the parasitic mites that are plaguing their industry, one expert says.

In theory, certain "lines" of mite-resistant bees might be bred and selected for their ability to naturally resist these deadly tracheal and varroa mites and reduce the current dependence on chemical controls.

But in reality, uncontrolled queen fertilization and the business practices of the commercial beekeeping industry make such

an approach very difficult, said Michael Burgett, a professor of apiculture at Oregon State University.

Burgett outlined the obstacles that may preclude a genetic solution in a recent article in the professional journal Bee Culture.

"Genetic resistance to mites is not a pie-inthe-sky solution, it's theoretically possible and should be researched," Burgett said. "But the constant movement and trade of bees in the real commercial world runs just opposite to the concept of controlled genetics."

In the meantime, Burgett said, the bee crisis continues to evolve.

The invasion to the United States of two types of parasitic mites that afflict honeybees - tracheal mites in 1984 and varroa mites in 1987 - is continuing to devastate wild populations and pose serious problems for commercial beekeepers, Burgett said.

"It's a true disaster for wild, or feral honey bees," Burgett said. "One California survey a few years ago showed 80 percent mortality of wild honey bees in a single year."

There are some chemical controls, or miticides, that have provided temporary salvation for commercial beekeepers, he said. But that presumes a level of professionalism that doesn't always exist. In Oregon, the number of registered non-commercial beekeepers has dropped by half in recent years, and the hives of honey bee hobbyists who don't use chemical treatments often die.

"Of course, the flip side of the problem is that large commercial beekeepers who know how to handle these mites have never been healthier or happier," Burgett said. "The value for pollination rental of every surviving hive has gone up, and the price of honey has doubled in the past 18 months. Many commercial beekeepers had a great year in 1996."

The looming threat, Burgett said, is that the mites will naturally develop resistance to chemical controls which are used so regularly. That's expected within 5-10 years, he said, and new chemicals or other approaches are desperately needed.

In that vein, many beekeepers thought that genetic resistance developed by laboratory research could be the ultimate solution, Burgett said.

Some strains of Africanized honey bees, in fact, have shown resistance to one or both of the mite problems. The problem can be alleviated by certain types of bee grooming behavior to physically remove the mites, a shorter life period in the pupa where the varroa mite reproduces, or physiological traits of the mites that limit their reproduction in some bees.

It had been speculated that such traits can be identified, cultivated and spread through the beekeeping industry. The U.S. Department of Agriculture, in fact, even released one strain of honey bee from Yugoslavia that it inaccurately maintained was resistant to varroa mites, Burgett said.

"The greatest problem is, bees don't live in a laboratory, they live in the real world," Burgett said. "Queens and bee hives are moved constantly, diluting and losing any genetic traits that a few select bees might have. And we have no practical way to control queen bee mating on a commercial scale."

Queen bees in an outdoor environment, Burgett said, will often interbreed with a dozen or more drones in a completely uncontrollable setting. So even if a queen were selected for certain desirable genetic traits, those traits might be quickly lost in a real-world setting, he said. And the current practices of commercial apiculture only magnify the problem, not reduce it.

For the near term, Burgett said, the most practical solution to the mite problems may be continued development of new chemicals and better hive management to reduce the overall stress on the bees.

For the threat facing wild honey bees, there is no obvious answer - and even if some wild bees showed resistance to the mites, their populations will be contaminated by the continued presence of non-resistant, commercially managed honey bees.

"Right now, there simply is no genetic solution to mites and there probably won't be anytime soon," Burgett said.