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Varroa Bee Mite, Now Resistant To Miticide, Again Threatens Honeybees

Cindy Spence

Malcolm Sanford (352) 392-1801
Laurence Cutts (352) 372-3505
Ray Zerba (904) 284-6355

GAINESVILLE—Beekeepers in Florida are facing their once and future nemesis, the Varroa bee mite, but this time they are doing it without a weapon, say University of Florida and state honeybee specialists.

When the mite first threatened honeybees 10 years ago upon its arrival on U.S. shores, beekeepers could turn to a miticide formulated in a plastic strip called Apistan. They placed the strip in the hives and as bees brushed against it they received protection from the mite.

Recently, however, beekeepers noticed the treatment was failing. Bee specialists investigated and found several colonies in which the mites have developed resistance to the miticide, and honeybees are beginning to die by the millions. Worse, there are no other approved miticides in beekeepers’ arsenal.

“By late spring, we could see an awful lot of bees die,” said Laurence Cutts, the state’s top bee inspector with the Florida Division of Plant Industry. “We’re in considerable trouble.”

As bees die, honey production could be hurt. In the United States, honeybees yield about 220 million pounds of honey a year, and Florida ranks in the top five annually in honey production, said Malcolm Sanford, the bee specialist at UF’s Institute of Food and Agricultural Sciences.

But the potential devastation doesn’t stop there.

Honeybees are also master pollinators, and many fruit, vegetable and horticultural crops depend on their assistance for pollination and fruit and seed set. And those crops are not limited to Florida. The state’s bees are shipped up and down the Eastern Seaboard, into the Midwest, and sometimes as far as California to pollinate crops.

The spread of the Varroa bee mite worldwide is the most significant event affecting beekeeping in the last century, Sanford said. As the mite hopscotched from continent to continent, Sanford said, beekeepers tried more than 140 different chemical treatments to fight it with little success.

Apistan’s arrival on the market in 1988 gave hope to beekeepers — many had lost up to 90 percent of their bees to the mite — but the now-resistant mites appears poised to wreak havoc again.

Cutts said 10,000 colonies already have been lost to the Varroa bee mite in recent weeks. While that does not seem like much out of the state’s 240,000 colonies, without a weapon to fight the mite the losses will continue unabated.

“We are desperately seeking a new product to use against the Varroa bee mite, but we are hitting roadblocks in every direction,” Cutts said. “If we could get one new product we could be back in high cotton. Without it, this problem will accelerate and will have a very serious impact on the bee industry and on agricultural production.”

The Varroa bee mite became resistant to fluvalinate, the active ingredient in Apistan, in eight years of use in Europe. U.S. beekeepers have gotten an extra two years out of the miticide, but they cannot turn to the products European beekeepers use because they are not allowed by the U.S. Environmental Protection Agency. While Apistan still works for some, most beekeepers dread its inevitable loss.

Many beekeepers have resorted to natural, botanical remedies in fighting the mite but with limited short-term success and no idea how the remedies will help in the long run.

“Nobody really knows how these alternative methods work,” Sanford said. “Treating for mites, hidden within the confines of one of nature’s most complex insect societies, is no easy task.”

Ray Zerba, a UF extension agent who started a honeybee education program with bee inspector Tom Mozer, said beekeeping education could help disseminate any new methods that come about for controlling mites while bolstering the declining ranks of beekeepers.

Even hobbyists are important: Of the 212,000 beekeepers nationwide, only 10,000 are professionals, according to Sanford’s top-rated Web site, APIS, named after the honeybee, Apis mellifera.

But Mozer says he has mixed sentiments about beekeeping education, despite recent increased interest.

“The mite wreaked havoc when it arrived 10 years ago. It was a new phenomenon in North America. Now it’s back with a vengeance,” Mozer said. “So at the same time we’re encouraging people to take up beekeeping, we have to warn them of the problems that may lie ahead.”

Sanford said it is unclear what the scope of the looming crisis might be. The earlier battle with the mite forced many marginal beekeepers out of business, he said. The effect of the latest skirmish with the mite, however, could be more severe.

“The era of let-alone beekeeping is gone. The mite’s presence demands even the most casual apiculturist actively manage the honeybee to its fullest potential,” Sanford said. “Bees used to take care of themselves. Now beekeepers have to take care of the bees.”