Untitled Document
The first reported
disappearances came late last year in Florida. By January, investigators
had determined that millions of individuals had gone missing, leaving few
if any clues as to why. The bizarre phenomenon has prompted a nationwide
scientific inquiry. In late March, a congressional subcommittee held a
hearing on the matter. As the quiet debate over the issue continues in the
halls of government and university laboratories, the body count has risen
with each passing day. Authorities in more than two dozen states have now
verified similar cases. Disappearances have also occurred recently across
Canada and Europe. If it were happening to a larger species, the plight
of Apis mellifera would
likely have spurred greater public outcry. Instead, the mass annihilation
has stayed mostly under the radar. But the dire situation has raised
concerns among some scientists who are struggling to understand it. “We don’t actually know what the
cause of the problem is in honeybees,” says May R. Berenbaum, an
entomologist at the University of Illinois at Urbana-Champaign, “but
one possibility is pesticide overload.” The scientist cautions that
there are many other possible causes. She and fellow entomologist Gene E.
Robinson, who is responsible for mapping the honeybee genome, are among the
top researchers delving into the mysterious malady, which has been dubbed
“colony-collapse disorder.”
Commercial beekeepers across the United States are
reporting colony losses from CCD of as much as 80 percent so far this year.
Worker bees are simply not returning to their hives. The absence of corpses
in or near the hives has led researchers to surmise that the insects have
lost their innate ability to make a beeline home. Something is causing the
bees to become disoriented after collecting nectar from flowering plants.
Their natural navigation systems have been thrown out of whack. They are
presumed to buzz around until they drop dead from exhaustion.
The alarming decline in these tiny foragers affects
more than just honey production. Honeybees are also used to pollinate more
than 90 fruit and vegetable crops in North America. Commercial beekeepers
move their hives from state to state, selling their pollination services to
farmers. Severe reductions in honeybee colonies would have a devastating
impact on America’s multibillion-dollar agricultural economy and,
ultimately, a sizable portion of its food supply. Although grain crops,
which are pollinated mainly by the wind, would not be widely affected,
apples, almonds, and broccoli are entirely reliant on honeybees.
Approximately one-third of the U.S. diet depends on honeybee pollination. A
national study published seven years ago put the estimated annual value of
bee-pollinated crops at nearly $14.6 billion.
The honeybees’
dilemma did not, however, begin with their recent disorientation. Populations have been waning for decades —
dropping, according to one estimate, by more than 40 percent since the
middle of the last century. In the mid-1980s, the introduction of two types
of bloodsucking parasitic mites exacerbated the decline. The parasites are
believed to have decimated populations of feral honeybees, too. In a
statement submitted to the House Subcommittee on Horticulture and Organic
Agriculture on March 29, Berenbaum warned that “if honeybee numbers
continue to decline at the rates documented from 1989 to 1996, managed
honeybees will cease to exist by 2035.”
Faced with the elimination of a huge percentage of
their colonies, many commercial beekeepers went out of business in the
1980s, leaving the remainder of the industry hard pressed to meet the
growing demand for services. Two years ago, colony shortages in California
led to the first importation of foreign bees since the passage of the
Honeybee Act of 1922. With so much riding on these creatures, Berenbaum is
astounded by the overall lack of apicultural knowledge. “Considering
how incredibly important economically honeybees are, we really know
pathetically little about them,” she says. “We don’t even
count them properly.”
She discovered the loose accounting procedures last
year while chairing a National Academies of Science research committee
charged with monitoring the status of North American pollinators. Berenbaum
reiterated her findings to Congress last month. “There is an
extraordinary paucity of reliable data on pollinator populations,”
she testified. “This dearth surprisingly applies even to the
honeybee, a species that has been semidomesticated and managed for
thousands of years.” Among other regulatory deficiencies, Berenbaum
pointed to longstanding Agriculture Department surveys that gauge only
honey production, not pollination services. Berenbaum, who refers to
honeybees as “six-legged livestock,” attributes the lax
governmental oversight in part to “a cultural bias against small
things.” In her congressional testimony she stated: “It is
difficult to think of any other multibillion-dollar agricultural enterprise
that is so casually monitored.”
Honeybees have been taken for granted, says
Berenbaum, even though they have been essential to American agriculture
since 16th-century colonialists imported them from Europe to pollinate
their apple orchards. Though the scale of operations has vastly increased,
beekeeping methods remain much the same as they were in 1852, when Lorenzo
Lorraine Langstroth, a Philadelphia clergyman, patented the movable-frame
hive. With the exception of pesticides used to fight parasites, the
artificial insemination of queen bees, a technique developed in the early
20th century, is considered by many the most recent innovation in
beekeeping. But CCD has created an urgent impetus for change. The
direction of that change is yet unclear, but there is a high probability
that genetic research will play a role as scientists move forward in
seeking to stem honeybee losses. In October 2006, only a month or so before
the disorder came to light, the Honeybee Genome Sequencing Consortium
published its finding in Nature magazine. Robinson, co-leader of the project, helped
generate a honeybee gene chip containing 11,000 genes. Together with
Berenbaum, he is poised to cooperate with other scientists at Penn State
University and elsewhere to help uncover the secrets of CCD. “One possibility we’re exploring is that
the bees have encountered some kind of toxin or another in the environment
due to pathogens or parasites or pesticides,” says Robinson.
“We’re going to be looking particularly to see if we see any
hint of that sort of response in the CCD bees.”
The research will involve comparing the gene activity
of CCD-affected honeybees with their healthy counterparts. “The
genome sequence gives us a parts list,” says Robinson. Researchers
will be looking for genetic differences between the two groups. “If
there is gene activity, the next question is, in what genes do we see the
changes?” he says. “After we ask that question, the next issue
is, do the identities of those genes give us any insight.” If genetic
alterations are discovered, Robinson says, researchers will analyze their
findings to determine whether genes known to respond to pathogens,
parasites, pesticides, or other causal factors have triggered changes in
CCD-affected honeybees.
The sequencing of the
honeybee genome has already revealed at least one disturbing
characteristic. “Honeybees have a vastly reduced inventory of
detoxification genes,” Berenbaum says. “They have the smallest
known inventory in this gene family of any insect. Fruit flies have 90
detoxification enzymes. Honeybees have about half that.” Scientists
don’t know why, but they hypothesize that honeybees, which thrive in
colonies of 30,000 or more, naturally shield themselves from outside
dangers through their social environment. “But we may have ratcheted
up the amount of unpleasantness to a level their system can’t
handle,” Berenbaum says. The “unpleasantness” may be rooted in a
number of natural or manmade causes or a combination of factors, including
viral, bacterial, and fungal diseases. Other possibilities include dietary
supplements, climate, and stress related to transport over long distances.
The latest theory, posited by researchers in Germany, is that cell-phone
signals are causing the disorientation. “I’ve been inundated
with people who say that it’s got to be GM [genetically modified]
corn pollen,” Berenbaum says. “If it’s GM corn pollen,
why isn’t there a single case of colony collapse in central Illinois,
where we’re in an ocean of GM corn pollen?” she asks.
“Cell phones, wireless Internet, Osama bin Laden, alien abduction,
chemical contrails [from] jet planes — people have sent me e-mails
suggesting all of these things.”
Besides pathogens, pesticides remain one of the more
plausible explanations for CCD. In 1999, the French government banned the
use of Gaucho brand pesticide on sunflower seed because beekeepers in
France strongly suspected the chemical of causing the same inexplicable
behavior now associated with CCD. The European press called it
“mad-bee disease.” A few years later, the French extended the
ban to corn seed for the same reason. German-based Bayer CropScience, the
manufacturer, denies responsibility for the bee die-off in France. Bayer referred all questions on the French ban and
other issues to CropLife America, the national association that represents
the pesticide industry. Spokeswoman Donna Uchida confirmed that the French
ban on Gaucho remains in effect even though the French government
acknowledges that the mortality rate among honeybees has continued to
increase since farmers quit using the pesticide. “The cause of
colony-collapse disorder is really unknown at this point,” says
Uchida. “The pesticide industry really supports the importance of
researching bee-health problems, because if farmers don’t have crops
because there is no pollination, then nobody would have a need for our
products, either.”
Imidacloprid — the chemical ingredient in
Gaucho — is used to treat corn seed and for an array of other
agricultural and pest-control purposes in the United States and 70 other
countries. It was first registered for use in the United States in 1992 and
is marketed by Bayer under various brand names to kill fleas on pets,
larvae in lawns, and many types of beetles, aphids, and other insects in
farm fields. When applied as a seed dressing, imidacloprid moves up the
plant stem and into the nectar and pollen, where honeybees and other
pollinators come into contact with it. It is also sprayed directly on a
wide range of crops, including grapes, potatoes, soybeans, and sugarcane. Imidacloprid is one of a group of insecticides
known as neonicotinoids, which are forms of synthetic nicotine that attack
the nervous systems of insects. A Congressional Research Service report
published last month noted that some beekeepers in the United States,
United Kingdom, and France have voiced concerns about imidacloprid. The
beekeepers fear that the chemical may “affect complex behaviors in
insects, including flight navigation, olfactory memory, recruitment,
foraging and coordination.” Moreover, in 2003, the Environmental
Protection Agency warned that a related chemical — clothianidin
— has the “potential for toxic chronic exposure to honeybees,
as well as other non-target pollinators.” The EPA report recommended
further study. “There are efforts now [at Penn State and
elsewhere] to determine what the precise field effects are to these
neonicotinoids,” Berenbaum says. The scrutiny is warranted
“because in laboratory studies they have been shown to have sublethal
effects on behavior,” she adds. “The fact that corpses are not
accumulating in front of the colony suggests that they [honeybees] are not
returning home and that perhaps their navigational systems are being
compromised, which neurotoxins can do. [But] it’s not a slam-dunk.
It’s a suggestion.”
In the absence of conclusive field results, Berenbaum
is reserving judgment. “Imidacloprid sales have been flat for the
last few years,” she says. “There’s no compelling
evidence for or against it, frankly. It’s not like there’s only
one pesticide out there. Some people think it’s a combination of
multiple exposures to different kinds of pesticides.” On the other
hand, Berenbaum says, “There are a number of people who believe that
it is a new pathogen, which is totally plausible as well. There are many
viruses that affect insect behavior.”
Part of the problem that agriculture now faces has
been caused by overreliance on a single species to pollinate crops. In that
regard, Berenbaum advocates taking such steps as creating a federal program
to set aside land as habitat for wild pollinators — but she also
seriously doubts that wild pollinators can ever be coaxed into carrying the
load now shouldered by honeybees. To secure their future and a hefty part
of the American agricultural sector, she asserts that lawmakers must
allocate more funds for research purposes when Congress reauthorizes the
Farm Bill later this year. In the meantime, Berenbaum and Robinson plan to carry
on their detective work without additional funding. “It’s a mystery,” Berenbaum says. “We can’t sit down with the patients and
ask them how they’re feeling. It makes it that much more
challenging.”
Freelance writer C.D. Stelzer wrote about Amtrak
service in central Illinois, “On the right track,” in the Jan.
25 issue of Illinois Times.
This article appears in Apr 19-25, 2007.
