The article below discusses the threat that a parasitic Asian mite poses to Honeybee colonies. , Commercial beekeepers are trying to breed a resistant strain of honey bee that can defend itself from this colony- invading parasite. Many experts and beekeepers agree this is a bigger threat to bees than pesticides, starvation, and colony collapse disorder.
Last January, California’s beekeepers were worried they wouldn’t have enough bees to pollinate the almond bloom, their biggest money-making event of the year. Gene Brandi, a California beekeeper and the former president of the American Beekeeping Federation, said winter losses were “as bad or worse than I believe it’s been.”
It turns out he was right. It was another grim year for America’s beekeepers, already reeling from more than a decade of colony losses that threaten the commercial honeybee industry. An annual survey released in June by the Bee Informed Partnership (BIP), a nonprofit collaboration of leading research labs and universities, found that beekeepers lost 38 percent of their colonies last winter, the highest winter figure since the survey began 13 years ago.
Managed honeybees play a crucial role in the nation’s food production, contributing an estimated $15 billion to the U.S. economy each year by helping to pollinate at least 90 crops.
Virtually everyone in the beekeeping business will tell you that the biggest threat facing honeybees isn’t pesticides, starvation, or even the mysterious affliction known as colony collapse disorder that made big news a dozen years ago. Instead, they’ll blame Varroa destructor, a parasitic Asian mite that snuck into the country more than 30 years ago. When asked to cite the three biggest risks to honeybees, Susan Cobey, a renowned expert on bee breeding at Washington State University, says, “Varroa, Varroa, Varroa.”
So far, the primary defense has been mite-killing pesticides known as miticides, but over time Varroa have developed resistance to some of them, and the beekeepers’ arsenal is diminishing quickly. “We think that Varroa are playing an increasing and very large role in these losses,” says Dennis vanEngelsdorp, a University of Maryland researcher working with the BIP. “In part because the products that are used to control them aren’t working as well, and also the viruses that they transmit are becoming more virulent.”
Even as Varroa continue to put enormous pressure on commercial beekeepers, and researchers work to breed bees that can better fight them off, another dangerous mite has been spreading in parts of Asia. If it arrives on our shores, it could push the beekeeping industry over the edge.
Female Varroa mites lurk in the darkness of a honeybee hive, waiting for the right moment to slip into the wax cells where young bees spend their youth, growing from egg to larva to pupa to adult. As larvae, the bees are ravenous, and their adult sisters, the nurse bees, visit them and provide food more than a thousand times a day. As a larva approaches its next life stage, it sends out a pheromonal signal; the nurse bees know they’ll soon need to put a waxen cap on the cell, so the young bee can complete its metamorphosis.
That discovery opens up new possibilities for developing more effective miticides. Samuel Ramsey, who conducted the fat body research as part of his dissertation in vanEngelsdorp’s lab at the University of Maryland, says, “the holy grail is to add some sort of miticide into the feed of the bees” that could be absorbed in the fat body. But the problem is that the mites can develop miticide resistance, as some already have.
One way bees can deal with Varroa is by taking the caps off larval cells and removing the mites. It seems straight-forward, but not all bees do it. They can also bite mites off of adult bees. These actions are genetic and bees that display these kinds of behaviors — like the Russian ones — are called Varroa-resistant. They are not, however, Varroa-proof and can still be overrun by too many mites.
Meanwhile, some beekeepers aren’t waiting for a well-tested Varroa-resistant bee. They’re trying a Darwinian approach by stopping miticide use. It’s a risky option when your livelihood depends on the bees. Nevertheless, Pettis says, “I’ve heard about a few big commercial beekeepers that have said, ‘I’m treatment free now. I’m taking my losses whatever they are now, it doesn’t matter.’ Because if you’re already losing 30 to 50 percent, it can’t get that much worse.
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