Mighty Bee Mites: Decimating the Pollinating Honeybee
Air Date: Week of July 26, 1996
A tiny development is having a major impact on national agriculture. Pollinating honeybees which are relied upon for spreading many kinds of seeds are being destroyed by two different species of mite. Matt Binder reports on how scientists and farmers are working to stay ahead of this stinging new problem.
NUNLEY: It's Living on Earth. I'm Jan Nunley. There is almost nothing more basic to life than a honeybee fertilizing a blossom, but it's not just flower gardens that need bees. Since humans became agriculturalists 10,000 years ago we've become dependent on these insect pollinators for a large part of our food supply. At first we planted crops and had faith that wild bees and other animals would pollinate them exactly when we needed them to. Eventually we began to domesticate bees, and ultimately to move them from farm to farm and region to region to ensure healthy and bountiful crops. Recently, though, the bees that most of us take for granted have been decimated by an invasion of 2 tiny mites. They've thrown the bee industry into a panic, and they threaten the US's precarious food web. Matt Binder reports.
BINDER: On a beautiful summer day in the hilly orchard country of central Ohio, the Ohio Fruit Growers Association is holding a business meeting and family get together at Bachman's Sunny Hill Fruit Farm.
(Ambient voices, adults and children)
BINDER: After a hayride tour of the orchard, a group of growers gets together among the apple trees to talk about the crash in the local bee population and the scramble earlier this spring to get their trees pollinated. Frank Hirsch grows 65 acres of apples, peaches, plums, and cherries, near Chilicothe.
HIRSCH: In our area we're surrounded by a lot of woods; we used to depend totally on the wild bees but there are none any more, so we had to increase the number of bees we could rent to do the pollination.
BINDER: Paul Bowers has 70 acres of apples and peaches in southeastern Ohio.
BOWERS: It used to be when my grandfather ran the orchard, he'd throw a couple of hives up in the orchard and they'd live, I don't care what you did with them, they lived. And they reproduced into another hive. I mean, if you had an empty box set beside it the next spring it was full of bees for you. And now, you can't keep bees in any box in your orchard. So it's -- if they don't get a handle on it quick, we're in trouble.
SAMMATARO: I'm going to look at some samples; let me open the freezer here and get --
(Ice is moved)
BINDER: Trying to get a handle on the bee parasite problem are entomologists like Diana Sammataro, whose grandfather taught her how to work bees when she was 12. Now she's a researcher at the Ohio State University Bee Laboratory in Wooster.
SAMMATARO: And unfortunately you have to take the bee apart to look for trichomite. And what you have to do is you have to take the head off, expose the tracheal tubes, which are these little white tubes that are just lying on top of the muscle tissue here.
BINDER: Sammataro started specializing in bee mites after a stint in the Peace Corps in the 70s, where she saw the Philippine bee industry decimated by mites and recognized the potential danger for US bee keepers. She's now afraid that she was right. Sammataro explains that there have been 2 separate invasions into the US of 2 different mites, one called the tracheal mite, which evolved on the Isle of Wight in England, and the other, called varroa, which originated in Asia. Both first appeared in the US in the mid-1980s.
SAMMATARO: Because bee keepers are always interested in upgrading their stock, varroa may have come in with a bee keeper illegally, bringing queens or bees into this country to augment their own apiaries and that's what we suspect. We can't -- we haven't proved anything yet.
BINDER: It's been illegal since 1922 to bring any live honeybee into this country, exactly to prevent what's happened. But because of the ban and because the honeybee isn't a native species, the honeybee gene pool here has become very shallow. Smuggling is suspected because varroa first showed up in Florida, where a lot of bee breeding is done. Sammataro says the other mite, the tracheal mite, probably traveled here indirectly, from Britain to South America first, as part of an agricultural aid program. Then, because beekeepers move their hives around so much to avoid frigid winter weather and to follow the crops in bloom, the mites rapidly spread with devastating consequences.
SAMMATARO: The varroa and tracheal mite have been in the US for about 10 years now, but this year it seems that most of the managed colonies have died. And that's anywhere from 50 to 90% of managed bee colonies on a national level. And probably all of the feral or wild bees have died in those past 10 years.
BINDER: The varroa mite is the worst of the 2 invaders. It kills almost 100% of bee colonies unless the hives are heavily managed and fitted with strips of a chemical called fluvalinate. But because fluvalinate is the only pesticide that's been found to safely and effectively control varroa, the mite is expected to quickly develop resistance to it. And then, says Sammataro, we'll be right back to where we started.
SAMMATARO: Honeybees, that's apis melliferum, are not native to the New World. They were first brought in by the Pilgrims and the colonists when they realized that apple trees that they had over here were not setting any fruit. And they concluded that what was missing from the orchards that were over here were honeybees. And it makes it ironic that apple growers today are coming around full circle, realizing that without bees, their apples aren't going to get pollinated.
BINDER: But it's not just apples, now. It's almonds, cukes, melons, berries, pears, plums, cherries, avocados, and just about every other flowering food crop except for grains, which are wind-pollinated. There are estimates that the honeybee crash will cost our economy $5 to $8 billion this year.
(Wood being sawed)
BINDER: The almost complete loss of feral honeybees means that growers are dependent on beekeepers at a time when the number of bee keepers is also rapidly going down.
ROHAN: It's probably the varroa that killed this one.
BINDER: How long ago was this one alive?
ROHAN: This one was alive earlier this year.
BINDER: Pat Rohan has been keeping bees in this eucalyptus grove just outside of Berkeley, California, for 20 years. He learned how to keep bees from his mother on the family farm in Ireland where, incidentally, bee keeping is considered women's work. A few years ago Rohan had 200 hives here, and his bees fertilized countless home gardens, fruit trees, and wildflowers. Now he has 10 hives left, and with the added labor and expense involved in fighting the mites, Rohan has decided to get out of bee keeping altogether.
ROHAN: The mite basically put me out of business. It seemed to happen in 3 weeks. I went from busy hives, good strong hives, to almost a wiped out apiary. They seemed to just collapse.
BINDER: Rohan is by no means atypical. The number of managed honeybee colonies in the US dropped from 4.3 million in 1985 to only 2.7 million in 1995. And with government cutbacks in bee research programs, progress toward a solution may be slow. But one small glimmer of hope has appeared.
(Industrial sounds. A woman speaks in Chinese.)
BINDER: It first appeared to Christine Peng, an entomologist at the bee biology lab at the University of California in Davis. She first kept bees as a teenager in Taiwan, and she's one of the few Western scientists who've traveled to Asia to study the varroa mite in its natural habitat, namely in the hives of the Oriental species of honeybee, apis serana. After months in Beijing, trying to get her experimental bees used to cameras, lights, and probes, she surprised the scientific world with a discovery captured on film.
PENG: Like this picture shows, the bees groom off the mites, are using their legs, and if the self-grooming behavior failed, then the bee will perform a grooming dance to get attention and help from the nest-mates. And once the mite is spotted and a worker bee will grab it with the mandibles, chew it really hard, try to kill it, and then will run out of the hive and dump it outside. So this was very exciting to us. What we are seeing is hygienic grooming behavior which has been described largely in the birds, and the mammals, and this is the first time we've ever seen happen in the insects.
BINDER: Peng hopes it will be possible to breed or genetically engineer our western honeybee to get it to perform this grooming behavior. But if that can't be done, she says, there's one sure way to control the mites: let natural selection take over. The mites will kill off all honeybees except the rare ones that are naturally resistant, and then beekeepers can breed these mite-resistant bees. This is exactly what happened in China in the 1960s, after Western honeybees were introduced there and they were decimated by varroa.
PENG: In those days, people didn't have very effective miticide to kill off the mites, so they basically just tried a few herbal things and gave up. And that's where, when you leave it to nature, the nature takes care of it. (Laughs)
(Many buzzing bees)
BINDER: But this natural selection process took 30 years in China, and if that happened here it would cause a major disruption in our food supply. Peng hopes that she and fellow scientists will be able to find a quicker solution.
BINDER: But until honeybees do recover, growers will have to rely on substitute pollinators to fertilize their crops. Steve Buchmann of the University of Arizona at Tucson has written a book about such alternatives, called The Forgotten Pollinators. He says there are 5,000 other pollinating species in this country, including insects, birds, and even some mammals like bats. But many of these creatures are also in trouble, threatened by pesticides and habitat destruction. And, Buchmann says, it's not just farmers who have to take responsibility for helping to protect them.
BUCHMANN: One of the things we can all do as backyard gardeners is to take a small stand, basically, in your own back yard. For example, one can put out a hummingbird feeder, or a butterfly feeder, and then at the same time perhaps rather than running for the can of insecticide go to the local nursery and buy some ladybugs or lacewings and try some biological control. Then you're going to be literally building up valuable populations of these native pollinators in your yard.
BINDER: Buchmann says it may be possible to domesticate some of these other pollinators, but it will take time and they'll never be as efficient or productive as the honeybee. In the meantime, he says, there's going to be an eerie silence in many orchards, farms, and gardens.
BUCHMANN: More than 30 years ago, Rachel Carson gave birth to the modern environmental movement with her now classic book Silent Spring. And among other dangers, she warned of a time when there was no pollination and there would be no fruit. No droning or buzzing of bees among the flowers. And now, here we are 3 decades later and with little public notice, her warning is coming to pass.
(Music up and under: "Sail on. Sail on my little honeybee, sail on...")
BINDER: For Living on Earth, I'm Matt Binder.
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