October 2007
Vanishing
Act — Scientists Beewildered by Honeybees’ Disappearance
By Juliann Payonk
Today’s Dietitian
Vol. 8 No. 10 P. 70
Experts have a bee in their bonnet—and
for good reason. As apiarists continue to lose hives, researchers
scramble for answers as to why the hard-working, pollinating,
agriculture-sustaining insects are perishing at alarming rates.
Overworked and underappreciated. At least, that’s
how Marla Spivak, PhD, a professor in the department of entomology
at the University of Minnesota, described U.S. honeybee colonies
earlier this year. Until recently, this may have been true,
as many people are blissfully unaware of bees’ substantial
contribution to the U.S. food supply.
However, due to the mysterious mass die-off
of honeybee colonies across the United States this past year,
honeybees have spent some much-deserved time in the spotlight.
Commercial beekeepers in more than 20 states have seen large
declines in hive populations since November 2006—more
than 70% in some cases. Will the U.S. food supply face crop
pollination complications because of these losses?
Bee Background
To grasp the gravity of this honeybee debacle, mites need an
introduction. Inadvertently introduced to the United States
in the 1980s, varroa and honeybee tracheal mites have been weakening
bee colonies for more than 20 years, leading to their collapse
and death. As such, beekeepers must continuously control these
pests—an increasingly difficult feat because mites have
begun to develop a resistance to treatments. Today’s honeybee
population is roughly one half of what it was in the ‘80s,
mainly due to these mites.
Dennis vanEngelsdorp, acting state apiarist
with the Pennsylvania Department of Agriculture, explains: “In
Pennsylvania, we had about 80,000 colonies in 1980, and we had
40,000 last year. There was a saying that before mites, you
could be a ‘beehaver,’ but now you have to be a
‘beekeeper’ because you have to actively manage
those mites.”
Adding to this stress on honeybees’ immune
system is the environment. Spivak says our environment is not
as bee-friendly as it once was. Urban sprawl and agricultural
practices have limited the amount of bee “pasture”
(flowers such as clover and alfalfa) available to bees for food,
and the use of pesticides adds to this stress.
Finally, commercial beekeepers transport thousands
of bee colonies across the nation each year to pollinate crops
for the U.S. food supply. For example, more than 1 million bee
colonies are required to pollinate almonds in California during
February and March, says Spivak. As such, moving large numbers
of colonies into a small area can place even more stress on
bees. With so much strain on the bee population, Spivak says
it’s no wonder bees are suffering.
Here and Now
Since last winter, honeybees have been mysteriously disappearing
from their hives in droves, leaving scientists stumped as to
what’s gone wrong. To date, what scientists have named
colony collapse disorder (CCD) has been reported in at least
20 U.S. states, five Canadian provinces, and several European
countries, costing U.S. beekeepers roughly $150 million in losses.
vanEngelsdorp describes how he first learned
of CCD nearly one year ago: “There was a very prominent
commercial beekeeper in Pennsylvania who moves his hives every
October to Florida. When he went down in November of last year
to visit them, he found that a lot of [the hives] were totally
empty—the bees had totally disappeared. I think he had
roughly 3,000 colonies and, in the end, he had 900 left.”
vanEngelsdorp says the beekeeper checked for
varroa mites, which he was used to managing, but the beekeeper
affirmed that the mites were under control. Samples were taken
from the hives and brought to Penn State University where Diana
Cox-Foster, MS, PhD, tested the bees for viruses. Other bees
from the same colonies were sent to vanEngelsdorp, who began
looking for mites and other known bee diseases.
“However, we never found high enough mite
or amoeba levels to justify [the mass die-off], but we found
clear indication that the bees were sick in the autopsies we
did on them. We saw a lot of scarring and a lot of other peculiar
things that we didn’t know how to explain,” he says.
At a national bee meeting in January, he says
it became clear that this bee ailment was happening all across
the United States. “So we received some emergency funding
and went down to Florida and California with the U.S. Department
of Agriculture [USDA] and took detailed samples from apiaries
in which colonies had either died, were dying, or were strong—so
we could get bees to actually examine—because in the dead
colonies there were no bees.”
A Thorough Analysis
The bee samples were then divided up for study, vanEngelsdorp
details: “North Carolina has been doing nutritional analysis
on the bees. Penn State with Columbia University have been doing
some pathology work, looking for both known or perhaps changed
bee illnesses. The USDA is studying what we call the ‘gene
chip.’ Last year, the honeybee had been [gene] sequenced,
and so we know there are certain genes that are turned on when
bees are facing stress. They’re also looking at mites
and a protozoa disease.”
Other samples were taken to Harrisburg, Pa.,
where autopsies are being performed on the samples, looking
at bees’ digestive systems and documenting any obvious
damage. Samples of pollen stored in the hive (called bee bread)
are being tested for pesticides and pathogens, and the wax itself
is being examined for any pesticide buildup. “So that’s
the main focus of the work,” says vanEngelsdorp, who adds
that as of July, “we’re beginning to get some data.”
Parallel to this, two other large studies were
initiated so that if this mysterious die-off happens in the
future, researchers can document where it starts and whether
there’s a difference between these treatment groups. “That’s
important for beekeepers because they want to be able to reuse
their equipment,” notes vanEngelsdorp. “We’re
not sure if CCD is a contagious condition, whether beekeepers
can reuse their equipment, and, if they can, how promptly they
can treat their equipment.”
More Questions
Than Answers
With so much research, one would hope scientists may have an
answer to the bee disappearances by now. Not so, says vanEngelsdorp,
but there are three principal hypotheses. “One is that
it is a pathogen, either new or newly emerged; two, it’s
an environmental stress, nutritional or genetic; or three, it’s
a pesticide, either farmer-applied or beekeeper-applied.
“And we’re still working to figure
that out,” he says. “The fact that we have so many
different illnesses in these bees when we look at them suggests
that there is some immune compromise going on, which makes it
much more difficult.”
Spivak agrees: “We do not know what causes
CCD. We do not know if it is a new disease pathogen, an environmental
pesticide, or a combination of a multitude of things.”
Dee Sandquist, MS, RD, CD, director of weight
management and nutrition for Southwest Washington Medical Center
in Vancouver, British Columbia, and a spokesperson for the American
Dietetic Association, offers another possible explanation. “Most
of the dead bees are near cornfields,” she explains. “Since
corn seed is coated with a pesticide, this may be the cause
of the disappearance. The pesticide blocks a pathway in insect
brains and leads to paralysis and death. Also, the pesticide
causes disorientation, which may explain why the dead bees are
not found close to their hives.”
How are scientists sure this bee disappearance
is not mite-related? vanEngelsdorp says that the hives abandoned
because of CCD show very different qualities than those with
mites. “You find large populations of varroa mites in
the colonies that collapse from these mites,” he explains.
“At the end of collapse, sometimes you’ll see bees
walking out of the apiary with crumbled wings, but they are
crawling from the apiary. The key is that we usually see them
in the apiary. In CCD, we’re not finding mites at any
appreciable level on the bees themselves, and we’re not
seeing this crawling behavior. We’re seeing a much more
rapid loss of bees.”
He adds that once a colony collapses from CCD,
there is lots of honey and pollen left in the colony, which
don’t seem to get robbed by other bees for at least two
to three weeks. And other known pests cohabiting in the hive
also don’t seem to consume the pollen or comb, which is
another curiosity. “Also, when a colony does collapse
[from CCD], we often will find just a handful of very young
bees and the queen,” vanEngelsdorp says, signifying that
the disease has affected all of the different aged bees in the
colony except the very young, who have probably just emerged.
Dinner-plate Deprivation?
So what do bees have to do with dietetics, anyway? An urban
legend recalls that Albert Einstein put it quite bluntly: “If
the bees disappeared off the surface of the globe, then man
would only have four years of life left. No more bees, no more
pollinations, no more plants, no more animals, no more man.”
Whether Einstein actually said this may be cause for debate,
but bees’ contribution to agriculture is a matter of fact.
A multitude of fruit, vegetable, and seed crops,
reportedly worth between $8 billion and $15 billion annually,
rely on honeybee pollination. Without a large enough bee population,
the quantity and quality of numerous much-loved produce will
suffer, including avocados, apples, blueberries, cotton, cranberries,
cucumbers, nuts, oranges, tomatoes, and watermelon. Even milk
would be affected, as many cows feed on alfalfa, whose seed
bees pollinate.
“Since commercially raised honeybees are
responsible for pollinating about a third of all food eaten
by Americans, it raises concerns for our food supply. They pollinate
more than 90% of flowering crops,” Sandquist says, noting
that roughly one third of our diet comes from insect-pollinated
plants.
Even though scientists are still looking for
the cause of CCD, there is no reason to panic just yet; grocery
stores should still be well-stocked with fruits and veggies
this fall and winter. vanEngelsdorp explains: “Most pollination
contracts have been met for this year. There were a lot of bees
imported from Australia to meet the almond demand. And beekeepers
help each other out and are very good at making splits and lending
each other bees if one guy is short for a pollination contract.”
However, Sandquist recommends that nutrition
professionals speak with their clients about the situation so
they can make informed dietary decisions if the food supply
were to be affected in the future. “Buy foods that are
available. Consider stocking up on frozen and canned fruits
and vegetables,” she says, reminding dietitians that there
is currently no cause for alarm.
“We’ll know when products are no
longer available or prices are high because of the lack of supply,”
she adds. “Recently, I attended a sustainability conference
in Portland, Ore., and one farmer who raises vegetables and
fruits mentioned there are fewer bees; however, production has
not yet been affected.”
Sandquist says that if the food supply were
affected by a lack of bees, it would be a great opportunity
for clients to diversify their dietary intake, exploring what
is available. “Definitely recommend trying the products
that are available,” she says.
A Bee-friendly
Future
Although the food supply seems to have survived this pollination
season, vanEngelsdorp says there is still cause for concern.
“Our real worry is that beekeepers have been losing bees
for 20 years now, since the mites have been here. And they’ve
become very good at replacing dead-out colonies. However, a
big hit like this isn’t easy to recover from. And so,
these people have had to go to the bank to get their operations
back up [and running]. If they get hit like this two years in
a row, we’re worried that some of these bigger guys are
going to be out of business.
“What really worries me about this is
that it hits so hard and so completely. If we lose a couple
of these larger operations, they’re not easily replaced,”
he continues. “It’s not like someone can get up
and become a beekeeper. You have to understand the biology management,
you have to be a mechanic, you have to be good with building
things with wood, etc. So there’s a very large skill set
that comes with [being a beekeeper]. They’re not easily
replaced.”
To compound matters, the current U.S. agricultural
system relies on the fact that we have a very portable and movable
pollination force, vanEngelsdorp says. “If one beekeeper
goes out, that same beekeeper can pollinate five or six different
crops up and down the coast. It will have an effect on each
of those. We need a very large and movable pollination force
to meet the pollination demands of the country.”
Spivak suggests the bee predicament may be better
solved with a more general shift in how the U.S. population
treats this silent wonder species. “It is very important
[for everyone] to cultivate plants and flowers for bees in gardens,
golf courses, agricultural land, everywhere,” she says.
“The most important thing to know is that
bees and all pollinators are suffering from our land use practices—that
is, our use of pesticides, which can harm and kill bees; our
use of herbicides, which kill the weeds and flowers that bees
get their nectar and pollen from; our practice of cutting weeds
from roadsides; and our lack of vegetation corridors to provide
food and shelter for pollinators and wildlife,” Spivak
concludes. “The problems that bees are encountering are
a reflection of our stewardship of the land.”
With the food supply ever increasing, there
is no longer a buffer in place for another die-off in the bee
population. As vanEngelsdorp kindly reminds us, “Five
years from now, there will be more almonds in bloom in California
than there are bees in the country to pollinate.”
— Juliann Payonk is an editorial assistant
at Today’s Dietitian.
Update
As this issue goes to press, reports indicate that scientists
may be one step closer to solving the mystery. Honeybees in
Australia are presenting with a deadly virus that may factor
into the U.S. colony collapse.
A Bee Well-traveled
Beekeeping was traditionally practiced for the bees’ honey
harvest. But in early 1908, U.S. beekeeper Nephi Miller decided
to try moving his hives to different areas of the country to
increase his productivity. Since then, migratory beekeeping
has become widespread, and crop pollination service today can
provide a majority of a commercial beekeeper’s income.
Modern hives enable beekeepers to transport
bees, moving from field to field as the crop needs pollinating
and allowing the beekeeper to charge for the pollination services
provided. Dennis vanEngelsdorp, acting state apiarist with the
Pennsylvania Department of Agriculture, has been monitoring
three East Coast commercial beekeeper operations. The following
are the routes each travels during an average year.
Beekeeper No. 1:
February — California for almonds
March — Florida for oranges
May — Maine for blueberries
June — Massachusetts for cranberries
July — Back to Florida
Beekeeper No. 2:
March — Florida for oranges
April — Pennsylvania for apples
May — Maine for blueberries
July — Pennsylvania for pumpkins
October — Back to Florida
Beekeeper No. 3:
March — Florida for oranges
April — New Jersey for highbush blueberries
May — New Jersey for cucumbers
June — Delaware for watermelons
July — Delaware for cucumbers or other melons
October — Back to Florida
What busy bees (and beekeepers)!
— JP
