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.

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