How Colony Collapse Disorder Works

The next time you enjoy some delicious almonds, take a minute to consider the hard-working bees that pollinate almond tree blossoms. See more insect pictures.
©iStockphoto/Todor Marholev

There are m­any products in modern life that can be difficult to trace back to their roots. Take the food you ate for supper last night. Have you ever considered the long journey your food made to get to your kitchen table?

Depending on exactly what you ate, it's likely that a fair portion of your food relied on bees -- specifically commercial honeybees -- at the critical early stages of its development. The little busybodies have been made even busier the past several decades as farming has evolved from small family businesses to large, concentrated single-crop farming operations that require pollination management. When there aren't enough existing bees in the area to handle the job (often because of habitat loss and pesticides), beekeepers are paid to bring their bees to help pollinate a crop.

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Beekeeping is big business -- take the almond pollination season for example. Migrating beekeepers descend on the vast California almond orchards every February, bringing with them more than 1 million hives (also called colonies) packed with about 40 billion honeybees. During the next few weeks, the bees pollinate 80 percent of the world's almond crop, worth about $1 billion in exports [source: Agnew]. Many other crops, like avocados, apples, cherries and melons, depend on the work of bees too. In the U.S., an estimated $15 billion worth of crops are pollinated by commercial honeybees each year [source: USDA].

And the bees' impact on your diet isn't limited to the actual food you eat, like those delicious almonds for example. Almond hulls are sold as cattle feed and the crushed shells as bedding for livestock, while the almond dust is collected as an additive to topsoil. So, even if you ate a hamburger for dinner last night and skimped on the fruits and veggies, your meal still might have had the help of a few bees.

But something dramatic is happening in the beekeeping world. Beehives have always been tricky to keep healthy and active because of issues maintaining proper nutrition and health. But now, the issue of healthy beehives has now reached new heights as Colony Collapse Disorder (CCD) affects an increasing number of hives.

Bees by the billions are heading out for a busy day of gathering nectar and spreading pollen, but mysteriously aren't returning to the hive. So why are bees flying the coop and where are they going? Let's dig a little deeper into the scope of CCD on the next page.

Vanishing Bees

Originally, CCD struck hardest in the U.S., but the condition has begun to turn up in other locales. British beekeeper John Hamer, seen here, tends to his bees at the Blackhorse Apiary Beekeeping Centre in St Johns.
Originally, CCD struck hardest in the U.S., but the condition has begun to turn up in other locales. British beekeeper John Hamer, seen here, tends to his bees at the Blackhorse Apiary Beekeeping Centre in St Johns.
Matt Cardy/Getty Images

Honeybees are social creatures, one of the reasons they're ideal pollinators for commercial beekeepers. They're relatively easy to transport and manage, and they aren't too picky about where their nectar comes from, so they can adapt to pollinating many plants.

However, the job of beekeeping is tough. There are several factors that can complicate the rearing of honeybees. For example, mites and fungi can infest a hive and cause health-related problems for the bees. It can be expensive and challenging to provide bees with all the proper nutrition they need, especially as foraging land becomes scarcer.

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Bees can also give their beekeeper a nasty shock when they go missing from their hives. Regular attrition rates are always present in hives and usually peak in winter (generally up to about 20 percent is normal), but Colony Collapse Disorder is on a whole other scale [source: Barrionuevo].

According to the USDA Agricultural Research Service, Colony Collapse Disorder may have been present in the U.S. as early as 2002, although it wasn't until 2006 that the numbers hit a fever pitch. Between October and December 2006, U.S. beekeepers saw their hives failing at rates much higher than the normal yearly turnover. Of the affected beekeepers, some 30 to 90 percent of their bees were dying. Between September 2007 and March 2008, U.S. losses were estimated at about 36 percent of managed hives [source: Science Daily].

Colony Collapse Disorder is characterized by the inexplicable absence of the majority of a hive's bees. Sometimes the queen, larvae and a few younger bees are still present, along with the colony's honey and bee bread (a combination of pollen and nectar), but the rest of the community is absent. An empty hive can be hot real estate in the insect world, especially if it's full of honey. But other insects, like moths, beetles and other bees that would typically leap at the chance to become the new tenants of a beehive, avoid CCD colonies for at least a few days. So what's happening to these vanishing bees?

This recent outbreak of CCD is not the first time bees have pulled a disappearing act, but it's the most severe and widespread. First noticed on a large scale in the U.S., cases have since been reported in other parts of the world like Europe. Although Australia has had trouble with CCD, the year 2008 turned out to be normal for beekeepers. CCD could spell disaster for the agriculture industry because of its reliance on honeybees as pollinators. Many industry leaders and researchers are looking into alternatives in the event the worst should happen and bees are no longer viable agricultural pollinators.

So what's making some bees fly off to greener pastures (or, more likely, fly off to die)? That's the million-dollar question that researchers and apiarists (beekeepers) are trying to answer. On the next page, we'll look at some of the possible causes of CCD.

Colony Collapse Disorder Causes

Typically, worker bees are quite industrious, so what makes them decide to take a hike -- possibly to that great beehive in the sky -- all of a sudden?
Typically, worker bees are quite industrious, so what makes them decide to take a hike -- possibly to that great beehive in the sky -- all of a sudden?
©iStockphoto/Vlado Janzekovi

Researchers have sifted through the list of possible Colony Collapse Disorder causes extensively during the past few years and haven't come up with one definitive answer. They have a few promising leads, however, and several factors yet to study.

At this point, the evidence seems to be leaning to the theory that CCD is caused by a couple of factors working in tandem. Here are some of the suspects who might share responsibility for Colony Collapse Disorder.

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  • Israeli acute paralysis virus (IAPV): This virus, first discovered by Israeli scientists in 2002, causes trembling, paralysis and death in bees. The virus has been found in many of the colonies abandoned by bees, but is also, on rare occasion, present in healthy colonies. As such, it's being considered a possible trigger or marker of CCD, but perhaps not its overriding cause. Recently, a study introduced IAPV into a healthy beehive that was enclosed in a greenhouse. Bees began dying within a week. Interestingly, researchers saw some of the functioning bees hauling the paralyzed bees out of the hive, as far away as the greenhouse would allow. The study's lead researcher said the results don't substantiate the theory that IAPV is the sole cause, but they do break promising ground.
  • Neonicotinoid pesticides: These pesticides -- including clothianidin -- are neurotoxins used to protect crops against pests. But, these chemicals may also be harming helpful pollinators. The EPA has noted clothianidin as highly toxic to honeybees, and many beekeepers in Germany are blaming it for the massive die-off rates that struck their colonies in May 2008. Scientists say early results aren't conclusive; tests on the dead bees found fairly low-level traces of the pesticide in nearly every instance. In theory, however, the insecticide could paralyze the bees while they're out collecting nectar.
  • Stress: Modern life may be more than some bees can handle. Researchers are looking to see if the pressures of being a 21st-century bee might be taking its toll. Many beekeepers are stretching the pollination season, giving their bees less time off to recuperate in the winter before hauling them to a new crop. Recent droughts can make finding an adequate amount of nectar a challenge for overworked foragers. These stressors, combined with factors like poor nutrition, could disrupt the bees' immune systems, making them more susceptible to disease.
  • Varroa mites: These parasitic creatures suck the bees' blood, leaving open wounds that can then become infected. The mites deprive bees of nutrition, as well as open the door for other pathogens to enter. Varroa mites, as well as other nasty mites, pathogens and fungi, can invade a hive and give the bees a run for their money.

Other factors under the magnifying glass include the chance that other (possibly unknown) pathogens or microorganisms are involved, or that honeybees might be lacking in genetic diversity. Some people have proposed that genetically modified crops are to blame, but this idea isn't high on the list of likely causes. One theory -- that cell phone and cell tower radiation are the culprits -- has been ruled out.

While it seems like there's a perfect storm of dangerous elements descending on bees, what makes matters worse is that bee populations frequently come into contact with one another. Some beekeepers try to keep their colonies isolated from other hives during pollination events to prevent any dangerous exposure from ailing hives.

So now that we've looked at some of the factors that could be causing Colony Collapse Disorder, let's take a look at what's being done to find some answers.

Colony Collapse Disorder Research

Bees need flowers, so tracking their floral pit stops can help researchers determine how bee populations are holding up.
Bees need flowers, so tracking their floral pit stops can help researchers determine how bee populations are holding up.
©iStockphoto/ululador

Commercial honeybees seem to be at the greatest risk for contracting CCD. Declines and hive abandonments have been noted in other bee species as well. Researchers are comparing healthy hives with CCD-affected hives to try to determine what's causing the phenomenon.

In addition, agriculturalists, apiarists and scientists are trying to find a replacement for the honeybee as the premium pollinator. They're looking to see if other species of bee, like the blue orchard bee, can be primed for the task.

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As research progresses, it's becoming clear that while there may still be one elusive culprit behind CCD, it's likely caused by a combination of factors. Because of this, finding an answer becomes a puzzle, as researchers struggle to discover the balance of factors that causes the fateful abandonment of a honeybee hive.

Scientists are toying with some tentative ideas to battle CCD. For example, if IAPV is a major factor, then the curious fact that some bees seem to have incorporated the virus' DNA into their genetic code and developed immunity could point the way to a solution. Immune bees could be bred with other bees, creating a population of protected hives. On the other hand, this could be how the virus causes CCD in the first place, so the idea still requires extensive testing to see if it's a viable option.

Some regions have banned the use of neonicotinoid pesticides to protect bee colonies. Whether this ban will solve the problem has yet to be seen. Researchers are finding a bevy of chemicals within beehives -- everything from crop pesticides to miticide treatments -- which may be interacting in harmful ways.

Researchers say more samples from around the world are needed to nail down what's causing CCD. For now, beekeepers can best care for their hives by ensuring their bees get all the nutrition they need and aren't being bothered by mites. Some beekeepers may want to minimize the impact of stress. Strategies for reducing stress may include finding better off-season foraging ground and decreasing travel.

Want to learn more about bees and other insects? Continue to the next page and visit the links.

Related HowStuffWorks Articles

More Great Links

Sources

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