March 26, 1995 in Nation/World

Bees Getting Bitten Mites Decimate Hives, Spread Like Plague

Dan Hansen Staff Writer
 

It could be a plot for a B-grade horror movie:

Ignorant or greedy beekeepers smuggle productive Asian queen bees into Florida without realizing the insects are infected with blood-sucking parasites.

The mites become the insect equivalent of a communicable disease, spreading from hive to hive, coast to coast, on the backs and in the windpipes of America’s sociable honeybees.

Wild honeybees are wiped out. Marginal beekeepers go bust and the number of domestic hives drops dramatically in a few years. Farmers worry their crops won’t be pollinated.

There’s even an unlikely hero: Pesticides, the traditional archvillain of bees, control the mites’ carnage among domestic hives whose keepers are diligent or lucky.

In the process, the bees become chemically dependent.

It’s no movie.

In the last three years, the number of domestic hives in Washington dropped 25 percent, according to state statistics. The number of beekeepers with five or more hives fell by the same amount.

Similar statistics aren’t available for Idaho. But the state’s Department of Agriculture says the mites are taking a similar toll there. In fact, numbers are down dramatically nationwide.

Cheap imported honey and the loss of federal honey subsidies are partly to blame for the decline. But beekeepers say those challenges pale in comparison to the two species of mites, which started showing up in the Northwest sometime about 1990.

Spring orders for bee colonies to repopulate empty hives are up at Tate’s Honey Farm, a Spokane Valley supply store.

“I’ve already taken orders for 100 (colonies) in addition to the 300 I normally sell,” said store owner Wes Tate.

Most orders come from people who have a hive or two, aren’t members of beekeeping clubs and might not even hear about the mites until their bees die.

“In the springtime, they were going like gangbusters,” said Green Bluff orchardist Lloyd Thorson, who was surprised when his two hives died last year. “It looked like it was going to be a great year.”

Commercial keepers have learned to treat for mites, even if their hives appear healthy. Buying and applying the mite-controlling pesticides adds about 15 percent to the cost of raising bees.

“There’s no sense even testing for (the mites),” said Don Miner of Spokane, who shuttles 1,200 hives between California almond fields and Central Washington orchards. “By the time you get the tests back, your bees are gone.”

Miner lost 40 percent of his hives five years ago, when his bees first were infected. He cut his losses to 6 percent this year “by treating exactly by the book.”

Without treatment, “we’d have about a 99 percent mortality rate” before a stronger honeybee emerged that could fend off the mites, said Mike Burgett, an Oregon State University entomologist.

One of the nation’s leading experts on bee mites, Burgett thinks wild honeybees will go through that natural selection process and bounce back, perhaps in a decade, maybe longer. Domestic bees won’t get the chance.

“No beekeeper can allow that to happen (and stay in business),” he said. “By treating, we mask the bee’s ability” to evolve.

Switching to Asian bees that withstand the mites isn’t a good solution, Burgett said. Asian bees that are gentle enough for domestication can’t survive temperate climates, something the unknown smugglers who brought the mites to America in the 1980s apparently didn’t know.

The two species of mites, varroa and tracheal, have different methods of attack and treatment.

Varroa mites - reddish-brown and about the size of a pinpoint - are the most common and the most deadly. They bore into honeycomb cells so they can feed on the blood of bee larva. They also suck blood from adult bees, in much the same manner as ticks attacking livestock.

Varroas are easily killed with pesticidal strips beekeepers place inside the hives. Strips for one hive cost about $3 through a popular beekeepers’ catalog.

“If I’m doing a very good job with treatment, I’m going to have a very low mortality rate,” Burgett said. “But it’s going to take a lot of work.”

Microscopic tracheal mites live and reproduce inside honeybee windpipes. They bore holes through the trachea to suck blood.

They are killed with menthol vapor that can be used only in the fall and is effective only if the daytime temperature is 60 degrees or warmer for two weeks. Menthol packets cost $2.65 per hive.

“You’ve got to keep the honey pure, so you’ve got to time the treatment right,” said Jan Dormaier of Honeybee Investigations in Hartline, Wash.

Exactly how the mites kill bees is open to speculation. Either they suck so much blood that the bees are too weak to survive, or they pass on deadly viruses. Some entomologists believe tracheal mites kill by making it difficult for bees to breath. Dormaier thinks tracheal mites may weaken the bees’ wing muscles, rendering them flightless.

For now, researchers lump all mite deaths under the heading “parasitic mite syndrome.”

As with the best horror stories, this one has some happy subplots:

Honey from infected hives is safe to eat, even if all the bees die.

Researchers don’t think bumblebees and the 1,000 or so other species native to North America are affected by the mites. (Honeybees arrived in the New World about 400 years ago with European keepers, and spread to the Northwest in the mid-1800s.)

At least one Texas researcher believes the mites are killing Africanized bees - often called killer bees by the public - in her state, according to The New Orleans TimesPicayune.

For reasons unknown, killer bees appear mite-resistent when they are closer to the equator, said Burgett.

Graphic: Bee hives decline

MEMO: This sidebar appeared with story: Bee shortage hikes cost of growing fruit The shortage of honeybees is forcing Northwest orchardists to pay more to grow attractive, plentiful fruit. With honey prices down, most commercial beekeepers rely on the money they’re paid by farmers who rely on the bees to cross-polinate blossoms each spring. Now, a plague of parasitic mites is making it more expensive to raise bees. Keepers are passing on some of the expense to farmers. Farmers in Washington and Oregon paid an average of $28 a hive to lease bees in 1994, said Mike Burgett, an Oregon State University entomologists who specializes in honeybees. The price was about $21 in 1993, he said. Orchardists typically lease a hive of bees for each acre of trees. The cost in the Northwest still is less than the $34 charged in California, where the bee shortage is forcing farmers to hire keepers from as far away as Florida. Even if the Northwest price doubled, it’d still be a bargain, Burgett said. The cost of leasing bees is only one-half of 1 percent of an orchardist’s return, he said. Without the insects, the trees either would bear less fruit or no fruit at all. Washington apples wouldn’t be nearly as attractive or tasty as consumers have come to expect. “I’ve never, never had a grower say to me, ‘My bees cost too much,”’ said Burgett, who has studied Northwest bees for 21 years.

This sidebar appeared with story: Bee shortage hikes cost of growing fruit The shortage of honeybees is forcing Northwest orchardists to pay more to grow attractive, plentiful fruit. With honey prices down, most commercial beekeepers rely on the money they’re paid by farmers who rely on the bees to cross-polinate blossoms each spring. Now, a plague of parasitic mites is making it more expensive to raise bees. Keepers are passing on some of the expense to farmers. Farmers in Washington and Oregon paid an average of $28 a hive to lease bees in 1994, said Mike Burgett, an Oregon State University entomologists who specializes in honeybees. The price was about $21 in 1993, he said. Orchardists typically lease a hive of bees for each acre of trees. The cost in the Northwest still is less than the $34 charged in California, where the bee shortage is forcing farmers to hire keepers from as far away as Florida. Even if the Northwest price doubled, it’d still be a bargain, Burgett said. The cost of leasing bees is only one-half of 1 percent of an orchardist’s return, he said. Without the insects, the trees either would bear less fruit or no fruit at all. Washington apples wouldn’t be nearly as attractive or tasty as consumers have come to expect. “I’ve never, never had a grower say to me, ‘My bees cost too much,”’ said Burgett, who has studied Northwest bees for 21 years.

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