Colony Collapse Disorder

Why are Honey Bees Disappearing?

Over the years, the United States beekeeping industry has faced obstacles to healthy bee management--from arthropod pests to pathogenic diseases. Now a new problem--"colony collapse disorder" (CCD)--threatens the industry. This disorder has gained considerable national and international attention.

What is Colony Collapse Disorder?
What Causes CCD?
Assessing the Disorder's Impact
Searching for Solutions
What Can Beekeepers Do to Avoid CCD?
Updates & Refereed Publications

What is Colony Collapse Disorder?

Bee colonies affected by colony collapse disorder (CCD) can appear healthy as few as three weeks prior to collapse, but then the adult bees disappear from the colonies--hence the historic nickname, "disappearing disease." The disappearing bees leave behind a box full of honey, pollen, capped brood, a queen, and maybe a few worker bees.

Beekeepers report that in colonies with CCD, dead bees are not found in the hive or on the ground outside of the colonies. Instead, the adult bees simply disappear. The final symptom is that small hive beetles, wax moths, and other nearby honey bees ignore the empty hive, even though the hive contains foodstuffs on which they ordinarily feed.

The Mid-Atlantic Apiculture Research and Extension Consortium (MAAREC) is the current clearing house for CCD-based information produced by the CCD Working Group. Composed of scientists, beekeepers, industry, and government officials, the CCD Working Group has defined the symptoms of CCD colonies as follows:

Collapsing Colonies

An insufficient number of bees to maintain the amount of brood in the colony
A workforce composed largely of younger adult bees
The presence of a queen
The cluster's reluctance to consume food provided to them by the beekeeper

Collapsed Colonies

Complete absence of adult bees in colonies, with few or no dead bees in or around colonies
The presence of capped brood
The presence of food stores--both honey and bee bread--that are not robbed by other bees or typical colony pests, such as small hive beetles or wax moths. If robbed, the robbing is delayed by a number of days

What Causes CCD?

CCD may not be a new disorder. Over the past fifty to sixty years, many colonies have died in connection with symptoms similar to those of CCD. In older literature, the symptoms were blamed on disorders called spring dwindle disease, fall dwindle disease, autumn collapse, May disease, and disappearing disease. These historic occurrences may not share a common cause with modern-day CCD, but they do share its symptoms.

The cause of CCD is currently under investigation. At this point, almost every possible and realistic cause remains a possibility. The following list of leading candidates--in no particular order--is not comprehensive and may change as new information becomes available. Such changes could result in the addition or exclusion of any of the following potential causes.

For more detailed information about each possible cause, see the original publication, Colony Collapse Disorder (CCD) in Honey Bees.

Traditional bee pests and diseases. These include American foulbrood, European foulbrood, chalkbrood, nosema, small hive beetles, and tracheal mites.
Style of feeding bees and type of bee food. The style of feeding bees and types of bee food used to feed bees vary considerably among beekeepers reporting CCD losses.
Bee management. Management style is a broad category, but it can include the type of income pursued with bees--honey production, pollination services--or the routine colony management that beekeepers perform--splitting hives, swarm control, chemical use.
Queen source. Lack of genetic diversity and lineage of bees--both related to queen quality--are being investigated as possible causes of CCD.
Chemical use in bee colonies. Chemicals used to control bee maladies have a variety of sub-lethal effects on all honey bees--workers, queens, and drones--even when the chemicals were used according to label and in accordance with best management practices suggested by specialists.
Chemical toxins in the environment. In addition to being exposed to toxins while foraging, honey bees may also encounter toxins by drinking water contaminated with chemical runoff, encountering various household or commercial chemicals outside of the hive, or via direct inhalation.
Genetically modified crops. Many seeds from which genetically modified crops are grown are dipped first in systemic insecticides that later may appear in the plants' nectar and pollen, making genetically modified plants suspect because of their chemical treatment history, not because of their modified genetics.
Varroa mites and associated pathogens. Varroa mites remain the world's most destructive honey bee killer, so they and the viruses they transmit are considered possible causes of CCD.
Nutritional fitness. Malnutrition causes stress to bees, possibly weakening the bees' immune systems. Weak immune systems can affect bees' ability to fight pests and diseases.
Undiscovered or new pests and diseases. Undiscovered, unidentified, or recently-introduced pests and pathogens are considered possible causes of CCD.

Many scientists believe that CCD is caused by some combination of the factors above. For example, some dead bees showing CCD symptoms have had elevated levels of normally-benign pathogens in their bodies, possibly indicating a compromised immune system.

In theory, any stress or combination of stresses--such as chemicals, genetic bottlenecks, or varroa--can suppress a bee's immune system. Considering synergistic effects as a potential cause of CCD makes the disorder increasingly more difficult to study.

Assessing the Disorder's Impact

Statistics Reported by Beekeepers

Beekeepers around the United States have reported higher-than-usual colony losses since the fall of 2006. In states reporting CCD, some beekeepers have lost fifty to ninety percent of their colonies, often within a matter of weeks. This translates into thousands of dead colonies and millions of dead bees. In a country where honey bees contribute billions of dollars in added revenue to the agriculture industry, these bee losses cannot be taken lightly.

So far, most CCD impact data are based on anecdotal reports and early surveys provided by beekeepers, but it is believed that since the fall of 2006, many thousands of bee colonies in the U.S. have died expressing symptoms of CCD.

Effects on the Agriculture Industry & Consumers

The production and sale of honey supports thousands of beekeeper families and provides consumers with an alternative to sugar. However, honey is of only minor importance compared to the benefits afforded humans by honey bee pollination.

Beekeepers who manage their bees for purposes of pollination load their colonies on trucks and move them around the country from crop to crop. Growers pay beekeepers to ensure an adequate supply of honey bees to pollinate their crop. In return, the growers benefit through higher fruit, vegetable, or nut production per acre; larger size and better product shape; and even enhanced product taste.

The benefits of honey bee pollination are not to be taken lightly. One estimate suggests that one-third of the world’s food production is directly dependent on honey bee pollination. The loss of bees could create a price war in the pollination industry, resulting in higher bee colony rent prices for growers. The average American may experience increased food prices and decreased food availability if honey bees continue to die at the current rates. In the worst case scenario, food availability may begin to decrease as honey bees die.

Signs of Environmental Problems

Honey bees are biological indicators, meaning that their status is a reflection of the general health of the environment. The rapid loss of colonies initiated by CCD in the U.S. and around the globe is alarming because the loss of bees may signal a decline in the health of the planet. It is possible that bee losses may be a symptom of a much greater environmental problem.

Searching for Solutions

Until recently, most of the work on CCD has been conducted by the CCD Working Group. That is changing as more scientists are beginning to investigate various avenues of CCD. Beekeepers, governmental officials, and scientists from universities, industries, and the USDA have initiated a number of investigations into the possible causes of CCD.

At this point, it is safe to assume that most potential causes of CCD are being investigated. Many granting agencies have realized the importance of honey bees and have begun to distribute research funds in an effort to find the cause and a cure.

What Can Beekeepers Do to Avoid CCD?

Although the primary cause or causes of colony collapse disorder is not yet known or understood, the following recommendations--based on information from the CCD Working Group--may provide beekeepers with some control options.

Do not combine collapsing colonies with otherwise healthy ones.
If you find abandoned hive equipment and the cause of bee death is suspicious, store the equipment in a manner that prohibits other bees from accessing it. Do not reuse this equipment.
To reduce stressors that may promote CCD, take steps to keep bees free of nosema.
When using an antibiotic to prevent or control American or European foulbrood, use one with a longer history of use in bee colonies.
To minimize the use of chemical miticides, use an integrated pest management (IPM) approach for varroa control in honey bee colonies.
Keep colonies strong by practicing best management practices.

For more detailed discussion of these tips, see the original publication, Colony Collapse Disorder (CCD) in Honey Bees. Contact your county Extension agent for more information about CCD, honey bees, or beekeeping in general.

Updates & Refereed Publications

Because CCD is new and not yet well-understood, there is a lack of refereed publications about the disorder. Visit the Mid-Atlantic Apiary Research and Extension Consortium (MAAREC) Web site for the most up-to-date information about CCD.