Colony collapse disorder (CCD) is a phenomenon in which worker bees from a beehive or European honey bee colony abruptly disappear. While such disappearances have occurred throughout the history of apiculture, the term colony collapse disorder was first applied to a drastic rise in the number of disappearances of Western honey bee colonies in North America in late 2006. Colony collapse is economically significant because many agricultural crops worldwide are pollinated by bees.
Signs and symptoms
A colony which has collapsed from CCD is generally characterized by all of these conditions occurring simultaneously:
- Presence of capped brood in abandoned colonies. Bees normally will not abandon a hive until the capped brood have all hatched.
- Presence of food stores, both honey and bee pollen.
- Presence of the queen bee. If the queen is not present, the hive died because it was queenless, which is not considered CCD.
- Precursor symptoms that may arise before the final colony collapse are:
- Insufficient workforce to maintain the brood that is present
- Workforce seems to be made up of young adult bees
- The colony members are reluctant to consume provided feed, such as sugar syrup and protein supplement.
The cause or causes of the syndrome are not yet fully understood. In 2007 some authorities attributed the problem to biotic factors such as Varroa mites and insect diseases (i.e., pathogens including Nosema apis and Israel acute paralysis virus). Other proposed causes include environmental change-related stresses, malnutrition, pesticides (e.g.. neonicotinoids such as clothianidin and imidacloprid), and migratory beekeeping. More speculative possibilities have included both cell phone radiation and genetically modified (GM) crops with pest control characteristics, though no evidence exists for either assertion. It has also been suggested that it may be due to a combination of many factors and that no single factor is the cause. The most recent report (USDA - 2010) states that "based on an initial analysis of collected bee samples (CCD- and non-CCD affected), reports have noted the high number of viruses and other pathogens, pesticides, and parasites present in CCD colonies, and lower levels in non-CCD colonies. This work suggests that a combination of environmental stressors may set off a cascade of events and contribute to a colony where weakened worker bees are more susceptible to pests and pathogens."
Applying proteomics-based pathogen screening tools in 2010, researchers announced they had identified a co-infection of invertebrate iridescent virus type 6 (IIV-6) and Nosema ceranae in all CCD colonies sampled. The study is the first to conclude that co-factors, the virus and fungus, were present in all of the collapsed colonies studied. However, scientists in the project emphasize additional research is still needed to consider how environmental factors like temperatures, drought and pesticides might play a role, if any, in CCD.
The exact mechanisms of CCD are still unknown, but many causes have been proposed as causative agents; malnutrition, pesticides, pathogens, immunodeficiencies, mites, fungus, beekeeping practices (such as the use of antibiotics, or long-distance transportation of beehives) and electromagnetic radiation. Whether any single factor or a combination of factors (acting independently in different areas affected by CCD, or acting in tandem) is responsible is still unknown for certain, however most recent information suggests a combination of factors is most likely. It is likewise still uncertain whether CCD is a genuinely new phenomenon as opposed to a known phenomenon that previously only had a minor impact.
At present, the primary source of information, and the presumed "lead" group investigating the phenomenon, is the Colony Collapse Disorder Working Group, based primarily at Pennsylvania State University. Their preliminary report pointed out some patterns but drew no strong conclusions. A survey of beekeepers early in 2007 indicated that most hobbyist beekeepers believed that starvation was the leading cause of death in their colonies while commercial beekeepers overwhelmingly believed that invertebrate pests (Varroa mites, honey bee tracheal mites, and/or small hive beetles) were the leading cause of colony mortality. A scholarly review in June 2007 similarly addressed numerous theories and possible contributing factor, but left the issue unresolved.
One of the patterns reported by the group at Pennsylvania State was that all producers in a preliminary survey noted a period of "extraordinary stress" affecting the colonies in question prior to their die-off, most commonly involving poor nutrition and/or drought. This is the only factor that all of the cases of CCD had in common in this report; accordingly, there is at least some significant possibility that the phenomenon is correlated to nutritional stress and may not manifest in healthy, well-nourished colonies. This is similar to the findings of a later independent survey in which small-scale beekeeping operations (up to 500 colonies) in several states reported their belief that malnutrition and/or weak colonies was the factor responsible for their bees dying in over 50% of the cases, whether the losses were believed to be due to CCD or not.
As of March 1, 2007 MAAREC (Mid-Atlantic Apiculture Research and Extension Consortium) offered the following tentative recommendations for beekeepers noticing the symptoms of CCD:
- Do not combine collapsing colonies with strong colonies.
- When a collapsed colony is found, store the equipment where you can use preventive measures to ensure that bees will not have access to it.
- If you feed your bees sugar syrup, use Fumagillin.
- If you are experiencing colony collapse and see a secondary infection, such as European Foulbrood, treat the colonies with Terramycin, not Tylan.
For more information: http://en.wikipedia.org/wiki/Colony_collapse_disorder
Source: Wikipedia (All text is available under the terms of the GNU Free Documentation License and Creative Commons Attribution-ShareAlike License.)