The Beekeeper's Lament (8 page)

No one knows exactly how the varroa mite first arrived on U.S. shores. Mite-infested bees could not have flown on their own from varroa-affected areas, even those in South America, where the mite had been found in the 1970s. Those places were beyond the reach of even the most determined swarm. Most beekeepers and scientists believe the varroa mite entered the United States not through Wisconsin, but through Florida, where most of beekeeping’s scourges seem to originate. Oreskovic and his neighbor Miksa both took their bees to Florida in the winter to pollinate citrus, bell pepper, and watermelon crops, and the hives on which Oreskovic first detected the mites had all been stocked with bees he had bought in central Florida.

Bee importation has been illegal in the United States since 1922, and the speculation is that the mite arrived either on a swarm that had taken refuge on a boat that docked in Florida or on an airplane. Miksa heard rumors that swarms had emerged from Drug Enforcement Administration planes flying between Florida and South America. Or perhaps they disembarked with beekeepers sneaking in queens from another country, a practice called “pocket importation,” because the smuggler literally hides the queen in a cage in his pocket or carry-on luggage. Not that it mattered: the mite had arrived, by whatever means, and by the time it was detected in Wisconsin, it had already spread extensively through Florida. By January 14, 1988, the Florida Department of Agriculture reported eight thousand infested hives in the state.

Once the presence of the mites was confirmed, the Federal Animal and Plant Health Inspection Service swung into action, receiving emergency certification from the U.S. Environmental Protection Agency for beekeepers to use fluvalinate, an insecticide that had proven effective against varroa mite in Europe and had been rapidly approved for sale in the States under the trade name of Apistan. When Miller found his first varroa mite, he quickly ran out to buy several thousand Apistan strips, flexible plastic sticks coated with low doses of the miticide. He placed them in his hives, and “they worked like a charm,” he recalls. At the same time, major beekeeping states like California moved to prevent varroa-infested hives from passing their borders. The Canadian government closed its borders to American bees and to queen breeders, who had previously done a booming business in Canada. Such quarantines did nothing to stop the spread of the pest, however. Swarms from infested hives had no regard for state lines or state laws, and worker bees plied the paths to their chosen blossoms from state to state. Many beekeepers, likewise, traveled their usual migration routes, evading quarantines by driving at night and on back roads.

It took two to three years from the time the first varroa mite was spotted until the nation’s first bee colonies started to experience difficulty. It took another couple of years until the mite, aided by large-scale migratory operations, had blanketed the country, jumping from hive to hive with alarming rapidity. During the first wave of infestation, the varroa mite killed nearly every single one of the continent’s feral colonies, obliterating the wild bees that once did much of the work pollinating the nation’s crops and flowers. Today, only an estimated 2 percent of the pre-1987 feral bee population remains, and those hives are most likely recently escaped swarms from beekeeping operations, not survivors of the varroa apocalypse. Because of the varroa mite, wild honey bees are now, for all practical purposes, extinct in the United States. If a bee guy doesn’t take care of his hive, it will be dead in less than two years; if a hive doesn’t have a bee guy to look after it, the chances of its survival are close to nil. Well-kept colonies like Miller’s escaped major damage only because of extreme vigilance and regular Apistan applications.

T
HE VARROA MITE WAS FIRST IDENTIFIED IN
Indonesia in 1904, when a naturalist named Edward Jacobson found a smattering of reddish brown mites in a colony of indigenous Asian
Apis cerana
honey bees on the island of Java. He sent them to the Leiden museum in Holland, where the Dutch biologist A. C. Oudemans determined that the insect belonged to a previously unidentified arachnid species. Oudemans gave it the taxonomic name
Varroa jacobsoni
, after its discoverer. It turned out that the parasites were endemic throughout Asia and did little damage to Asian bees, having coevolved over millions of years. The Asian bees had developed a natural defense, detecting mites on adult bees and in capped cells and ejecting them. So for another century after Jacobson’s discovery, no one bothered to take a deeper look.

Entomologists believe that European honey bees (
Apis mellifera
) and Asian honey bees (
Apis cerana
) branched from the same genetic forebear a few million years ago. Like European bees, Asian bees live in colonies, produce honey, and can be easily domesticated. Asian bees are smaller and less hairy, with more distinct stripes on the abdomen, and they tend to fly faster and more erratically. They are also more defensive. They swarm and spread more quickly, and their smaller colonies produce less honey. Thus it is the European bee that has accompanied humans, spreading from Europe to every temperate place where humans have settled. Scientists speculate that some one hundred years ago, the European bee completed its circumnavigation of the globe. They believe it moved from west to east via the Trans-Siberian Railroad and was reunited in Asia with its Eastern siblings, as well as the mites with which they coexisted.

Sometime in the early 1950s, the mite made its own fateful move. Some—perhaps only one—of those Asian mites jumped successfully from
Apis cerana
onto the Western honey bee. Scientists believe it happened somewhere in eastern Russia. In the 1960s, the mite spread through Russia and North Africa. By the 1970s, it had moved across Europe; mites were found in Paraguay in the 1970s, too. Someone also found a lone mite in Maryland in 1979. But until Gary Oreskovic spotted his bloodred tick on a September Wisconsin morning in 1987, the United States considered itself uninfested. No more: the mites blanketed the North American continent in the late 1980s and early 1990s, then jumped to South Africa. They reached New Zealand in 2000, where beekeepers lost more than thirty thousand hives; more than two thousand beekeepers “retired” soon after. In 2008, mites landed in Hawaii. To date, Australia is the only major beekeeping nation that has not hosted a mite. The varroa mite had once lived in the inconspicuous shadows where most creepy-crawly species reside, garnering little attention. But once it pitched the entire global bee supply into precipitous decline, this previously harmless parasite was, abruptly, the bee world’s public enemy number one.

So the bee world embarked on a crash course in varroa mite physiology. For four decades now, entomologists have studied it intensely, learning about its life cycle, its sex life, its behavioral propensities, its chemical sensitivities. The more they’ve learned, the more complex they’ve found the mite’s relationship with the honey bee to be. For instance, the mite’s effects appeared to vary as it traveled the globe: bees in South America and eastern Russia were relatively resistant; those in Western Europe and North America suffered near-universal mortality. In addition, the varroa mites on European bees were noticeably larger than those on their Asian siblings; scientists first attributed this variation to the fact that European bees and colonies are larger, offering the mites more nutrients and hosts on which to thrive. But in 2000, an Australian bee pathologist named Denis Anderson reached another conclusion.

I first heard Denis Anderson speak about the varroa mite at a beekeeping conference I attended with John Miller. Anderson wore jeans and a collared shirt opened a couple of buttons farther than most insect geeks would dare; he looked more Steve Irwin swashbuckler than entomology nerd, and he made varroa mites sound as interesting—and menacing—as saltwater crocodiles or box jellyfish. Anderson smiles easily, almost compulsively. He’s got quizzical arched eyebrows, a sharp nose, and a boyish face ringed by thick, shaggy brown hair and a beard. Although he is pushing sixty, his hair betrays barely a hint of gray. He travels the world studying bees and their diseases, spending six months a year at the entomology department of the Commonwealth Scientific and Industrial Research Organisation in Canberra, and the other six months in the field studying bee diseases and pests across Asia. He is the principal scientist working on bee populations and the varroa mite in Australia, which, as the last varroa-free bastion, has the luxury of devoting funds to more esoteric investigations than do afflicted nations, whose research dollars go mainly toward finding chemicals to kill it.

Anderson first began working with the varroa mite while doing field research in Papua New Guinea, Australia’s closest neighbor to the north. It was a fascinating place for a bee pathologist. Thanks to the political and migratory forces that swept the island of New Guinea in the twentieth century, Asian and European bees intermingled there, providing an excellent laboratory for observing the behaviors of the pathogens they shared. Australian missionaries had brought European bees to New Guinea before World War I, while Asian honey bees arrived in the 1970s, after the Indonesian government relocated thousands of Javanese farmers to Irian Jaya, on the western side of the island. Those peasants brought their own domestic animals, such as chickens, pigs, and Asian bees. And they also brought the Asian bees’ theretofore harmless co-rider,
Varroa jacobsoni
.

It was 1989, just a couple of years after the mite had arrived in the United States, and Anderson was well aware of the damage inflicted on European bees in the Northern Hemisphere. In New Guinea, the mite was everywhere, on both European and Asian bees. But Anderson quickly noticed that it seemed to behave differently on the European bees of New Guinea than on European bees elsewhere. The mites weren’t able to reproduce inside the brood cells, and thus were unable to spawn populations large enough to endanger hives. “When I first saw this I was new to the varroa mite and I thought, ‘What I’m looking at here is just an aberration,’ ” Anderson says. But it wasn’t an aberration; it was the norm there. Varroa mites were not able to replicate in European hives. “I looked at it for four years and said, ‘Look, this mite is not reproducing.’ ”

The question was why: were the European bees resistant to varroa mites in New Guinea, or were the mites themselves different? Anderson devised an experiment. He raised European queen bees in Perth, Australia, and he artificially inseminated them with semen from a single drone, so their offspring would come from a narrow genetic base. Then he moved twenty of those offspring to New Guinea and twenty to Germany, to see how they responded to the mites found in each location. In New Guinea, the hives did fine. In Germany, they collapsed. The mites found in Germany could readily reproduce in the Perth bee colonies. Those in New Guinea could not.

He then conducted the same experiment in Java, the densely populated island that is home to Indonesia’s capital city, Jakarta, and found that the mites there could not reproduce in European colonies. But in 1994, soon after Anderson’s experiment concluded, he began hearing reports that varroa mites in Java had suddenly begun to reproduce on European bees, killing colonies across the island. He examined samples of mites from collapsing hives and noticed that they were much larger than the ones he had studied in New Guinea and Java in previous years. And while the larger mites had overrun the hives, he could also find the smaller mites—which were still not reproducing. It was then, he says, that he had his own eureka moment: “I realized that there were two mites here,” he says.

The new mites in Java were not only larger; they were also more oblong. By the mid-1990s, DNA technology had evolved to the point where it was possible to sequence segments of the genetic code from the mites. So Anderson studied the variation in sequence of a particular mitochondrial gene on both mites and found them to be different. He then traveled across Asia collecting additional samples, sequencing their genes as well. He discovered that there was not just one mite riding around on the world’s Asian honey bees, but a complex of mites, comprising four entirely different species and eighteen separate regional genotypes. Of those eighteen, only two were found in European bee colonies globally—and neither belonged to the species that had long been blamed for causing the damage to global bee populations.
Varroa jacobsoni
, the mite Anderson found in New Guinea, was native to Indonesia and could not reproduce in the brood of the European bee
.
It was, University of Georgia entomologist Keith Delaplane wrote in a 2001 editorial in a bee science journal, a “benign homebody, still restricted essentially to its original host . . . and not the culprit to worldwide calamity that we had thought.” The mites didn’t behave differently in different regions because the host bees were different. No, the mites behaved differently because they were, in fact, different mites. For three decades, Anderson realized, entomologists had been studying the wrong mite.

The culprit was not
Varroa jacobsoni
, but the larger mite, one of the two genotypes that could reproduce in European bees. One of the offending genotypes had originated somewhere on the Korean peninsula; the other in Japan. The Japanese mite was the one that had found its way to South America in the 1970s via a shipment of varroa-infested bees from Japan to Paraguay. It had remained restricted in both the damage it caused and the scope of its spread. The far more pathogenic variant had evolved on the Korean peninsula. At some point it made the transspecies jump from
Apis cerana
onto Russian bees and spread to Europe and the United States. Those Korean mites showed little genetic variation in Anderson’s studies, suggesting that there may have been only one single female mite that made the reproductive jump between hosts—a founding foundress, so to speak, that cloned herself around the world. Delaplane compared Anderson’s discovery to a “scientific revolution,” if not on par with the discovery of gravity and relativity, one that was nonetheless earth-shattering “for that fraction of the world’s scientists who work on the parasitology of
Apis mellifera
.” As discoverer of a new species, Anderson was entitled to naming rights. Rather than christening it
Varroa andersonii
—“I don’t think I would like to be remembered as a parasitic mite”—or by reference to its homeland, he opted for a devastatingly apt, melodramatic, even comic-bookish moniker:
Varroa destructor
.