Better Planet: Beepocalypse
06.28.2007 
Can we save honey bees from Colony Collapse Disorder?
by Josie Glausiusz 

Normally, the announcement that yet another species is in danger does not
trigger economic jitters and hyperbolic headlines—but there is nothing
normal about the disappearance of honeybees. The die-off has been rapid and
inexplicable. The first reports surfaced in October 2006; within months
beekeepers in 27 states, from Florida to California, reported a serious
decline in the insects, and similar troubles were showing up in Canada and
Europe. And honeybees, or Apis mellifera, are big business: Bee pollination
of agricultural crops—everything from almonds to apples to carrots—provides
one-third of the U.S. diet, and the bees’ services are valued at $15 billion
annually. If these six-legged laborers vanish, then many of the staples that
we take for granted could be threatened—and a lot more expensive. By March
2007, Congressional hearings were under way to explore how Colony Collapse
Disorder, as the bee syndrome has been dubbed, threatens America’s
agricultural vitality and what can be done about it.
 
There is no easy answer to the problem. Colony Collapse Disorder, or CCD,
appears to differ significantly from previous bee maladies in that the bees
simply fly away from the hive and never return, leaving behind only an
egg-laying queen and a few young workers. Colony losses first seemed to be
restricted to migratory beekeepers, merchants who transport hundreds of
beehives from state to state, selling pollination services to farmers.
Hypotheses proliferated: A brand-new disease is killing the insects.
Pesticides are disrupting bees’ ability to navigate. Parasitic mites are
weakening them. Mite-killing chemicals, sprayed into the hives, are building
up in the wax and eliminating the bees instead. It’s a fungus. It’s a virus.
Maybe vibrations in the trucks that transport bees across the country are
driving the little buzzers insane. Overwhelming stress is making the bees
vulnerable to disease. And some of these conjectures sound truly loopy. The
British newspaper The Independent ran an article anxiously asking, “Are
mobile phones wiping out our bees?” It floated a baseless theory—citing a
study that was not, in fact, carried out—that radiation from cell phones was
disorienting the bees.

Further muddying matters, some researchers claim that the disorder is simply
an extreme variant on an existing disease, pointing to similar, if
smaller-scale, outbreaks of “disappearing disease” among bees that struck in
the 1930s and 1970s, with equal lack of explanation. But everyone agrees
that something peculiar is happening, and nobody knows exactly why.
Nancy Ostiguy, an entomologist at Penn State University, sees signs that the
culprit is a new pathogen. She notes that the abandoned colonies are filled
with food. Normally, neighboring bees would swoop into forsaken hives and
steal honey and pollen. Yet neither robber bees nor pests like wax moths and
small hive beetles are entering the emptied bee boxes. “One of the working
hypotheses is that there is a fungus that hasn’t been in the colonies
before,” Ostiguy says. “The hypothesis is that this fungus, which either has
killed the bees or come in later, is producing a toxin.” The toxin might be
so repellent that the bees desert the hive.

Axel Decourtye, an ecotoxicologist at the Association de Coordination
Technique Agricole in Marcy l’Étoile, France, is looking instead at a
chemical cause. He is focusing on a class of insecticides called
neonicotinoids, and in particular imidacloprid, which is used to coat
sunflower seeds and then suffuses the plants’ tissues as they grow. His
studies have shown that imidacloprid can impair honeybee memory and their
ability to learn new odors, which leads biologists to suspect that forager
bees exposed to this pesticide might become lost and die far from the hive.
Yet even after France banned imidacloprid in 1999, honey¬bee populations in
France continued to plummet, according to Decourtye’s collaborator Nicolas
Desneux of the University of Minnesota. “There are no experimental field
data so far showing that these products are responsible for the global
decline in bee populations,” Desneux says. Still, no one has shown that
agricultural pesticides—and there are quite a lot of them—are not a cause of
CCD.

Amidst this perplexity, other researchers are searching for ways to save the
bees before it is too late. One tactic is to boost the insects’ ability to
defend themselves against parasites and pathogens. Since 1993 Marla Spivak,
an entomologist at the University of Minnesota, has been breeding a strain
of honeybee that can smell the rotting odor of American foulbrood, a
bacterial infection, as well as the yeasty whiff of chalkbrood, a fungal
disease; they can also detect parasitic varroa mite infestations in young
bee pupae. Spivak’s custom-bred worker bees can patrol the hive, pierce the
cells in which affected offspring are growing, and remove them—and sometimes
eat them—before disease or parasites have an opportunity to spread through
the hive.

Although such “hygienic bees” would eliminate the need for antibiotic
applications in hives, Spivak admits that they are unlikely to provide a
long-term solution to Colony Collapse Disorder. She believes its causes are
multiple: mites and viruses, residues of chemical mite killers,
cross-country transportation, nutritional stress from tainted corn-syrup
feed or pollen supplements, and pesticide exposure. “In my mind those
symptoms are not new. Abandoning the nest—many things would cause that.”

Multiple causes could make it extremely difficult to stop the decline of the
bees. If so, farmers may have to embrace a change in strategy and encourage
the assistance of alternative pollinators like solitary wild bees and
bumblebees. A promising study published last autumn by ecologists Sarah
Greenleaf of the University of California at Davis and Claire Kremen of the
University of California at Berkeley found that the presence of wild bees
increases the efficiency of sunflower pollination fivefold. “You see these
female bees with these huge loads of pollen on them, dive-bombing the
honeybees on the flowers that the wild bees want to be on,” says Greenleaf.
Being bumped off one flower seems to prompt the honeybees to move the pollen
from the male plants over to the female plants—which is exactly where the
farmer needs it to go.

Greenleaf and Kremen counted 33 species of wild bee in the sunflower fields
of Central Valley in California. These bees nest in underground tunnels or
hollow twigs in nearby natural habitat—oak woodlands and chaparral, or dense
shrubland. But such lands are under serious threat from giant single-crop
farms. “These big giant monocultures pretty much hammer the bee habitat,”
says Mace Vaughan, an entomologist and conservation director of the Xerces
Society in Portland, Oregon, which promotes insect biodiversity. “If you go
from the foothills of the coast range in California and go out into the
heart of the Central Valley, the bee diversity and abundance just steadily
drops off.”

One solution is to enhance the habitat for native bees around farmland—by
planting hedgerows, for example, or leaving some land uncultivated. Vaughan
cites research that Canadian canola farmers who sow seeds on only 70 percent
of their land (leaving the remainder as wild habitat for native bees) are
more productive, and make more money, than those who plant the crop on all
of their fields. Another approach is to encourage managers of semiartificial
environments like golf courses to surround the greens with the types of
plants, like sunflowers, lupines, and black-eyed susans, that attract native
pollinators.

Bees in the wild are under serious threat from agriculture: “These big giant
monocultures pretty much hammer the bee habitat.”

Jim Cane, an entomologist at the U.S. Department of Agriculture Bee Biology
and Systematics Lab in Utah, is working on ways that wild bees could replace
honey¬bees on some crops, rather than merely supplementing them. Bumblebees
are already raised commercially for pollinating greenhouse tomatoes. Cane
has successfully raised a range of native bees for other kinds of commercial
use. Leaf-cutter bees and alkali bees pollinate alfalfa, the blue orchard
bee pollinates fruit trees (especially almonds), wild bee species Osmia
aglaia and O. bruneri pollinate raspberries and blackberries, and O.
ribifloris is effective at tending to blueberries. In most cases, managing
these bees means providing habitat in which they can nest, like drilled
wooden boards or hole-studded stone blocks for cavity-nesting species like
the blue orchard bee.

Replacing honeybees with wild bees is not as simple as it sounds, however.
Many wild species specialize on one or two crops, and they can be expensive
to raise. By contrast, says Cane, “The honey¬bee is a jack-of-all-trades.
You can plop them down in mustard, in apples, in blueberries, whatever crop,
and they’ll visit and give you pollination. With honeybees, you can provide
hundreds of thousands of foragers very cheaply—less than a penny a forager.”
All the more reason, then, to be concerned about their disappearance. Yet
Cane remains skeptical about the severity of CCD. “Clearly, some beekeepers
have had some disasters this winter, and I do feel for them,” he says. “But
the magnitude, extent, scale, and certainly cause are still open questions.”

One big block in understanding what is happening to the bees is a lack of
hard data: Many states in the past decades have dismantled their apiary
inspection programs. “Bean counters said, ‘Well that one job, that’s a lot
of money we could save in our budget, nobody’s clamoring for it, so let’s
just jettison it,’ ” Cane says. Had inspectors had the opportunity to
examine commercial hives across states, “we’d be six months ahead of where
we are now.”

Meanwhile, ordinary people can help keep pollinators abundant. For example,
they can scatter hole-punched bee blocks in their gardens in which wild bees
can nest. Vaughan of the Xerces Society encourages planting lots of backyard
flowering plants that bloom year-round. “But the best thing for the average
Joe to do is reduce or eliminate his or her use of pesticides around the
house,” he says. “These kill more good pollinators than bad things.”

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