The mysterious ailment afflicting honeybee colonies throughout the United States and the world is continuing to reduce populations of this vital insect, and bee experts still aren’t sure what’s to blame. That’s the word from the U.S. Agricultural Research Service and the Apiary Inspectors of America, which together have just completed a national survey of beekeepers to gauge how the nation’s honeybee colonies fared over the winter of 2007-08.

According to the study, beekeepers reported an average loss of just over 36% of their colonies over winter, a figure up 13.5% from the previous year, and just over a third of all beekeepers reported losing one or more of their colonies to the condition named Colony Collapse Disorder (CCD).

Altogether, there are roughly 2.44 million honeybee colonies in the United States. Since 2006, their keepers have been reporting the sudden and unusual disappearance of large numbers of them. Virtually overnight, all the adult bees in a seemingly healthy hive will vanish without a trace.

photo: kuribo

Because no bodies are left behind to examine, researchers studying the situation have had extreme difficulty locating clues to what’s behind CCD, and the scientific community remains in the dark about both the cause and its cure. To combat this lack of evidence, scientists have begun monitoring healthy colonies across the country. Should CCD strike one of them, researchers hope they’ll have a trail of data they can follow to an answer.

In the meantime, a number of theories about CCD’s cause or causes are currently circulating in the scientific community. These variously lay the blame on pesticides and/or some other environmental contamination; poor synthetic diets fed to bees when natural food is scarce; stresses placed on colonies that are frequently transported; pathogens, specifically the Israel acute paralysis virus; a infestation of a creature called the Varroa mite, which carries this and many other bee diseases; or some combination of any or all of the above.

Lately, researchers looking into the problem are leaning toward the combination theory. Recent data finds that CCD appears to sweep through colonies in a pattern typical of the spread of disease (i.e. spreading outward in a certain direction or directions from a single “ground zero” point). There are also clues that suggest healthy colonies are being infected by ill colonies that they encounter when several beekeepers bring their bees together for agricultural pollination. Many apian experts believe that bee immune systems already under stress from some combination of external factors like malnutrition or pollution are unable to cope with the introduction of a virus or parasite and so entire colonies perish from causes they might otherwise resist.

Adding fuel to this fire is a new study from the University of Virginia, which found that ozone and other types of air pollution destroys the scent of flowers and therefore impedes the ability of honeybees to trace these delicate fragrances to their source and find food.

As critical pollinators of many of the foods we depend upon, healthy honeybee populations are essential to our food supply. About 130 different crops rely upon honeybee pollination. Some 30% of the all the different types of nuts, fruits, and vegetables we consume, a harvest worth $15 billion a year, will disappear if honeybees do.

That makes finding the cause or causes of CCD a critical mission. And it makes anything we can do at home to help honeybees vitally important, too. The Natural Resources Defense Council suggests steps like these:

• Plant species native to your region in your yard and garden. These will provide abundant food for local bee populations.

• Grow a wide variety of plants with different colors, shapes, and flowering times. A diverse range of plants will attract an equally diverse range of bee species and give them plenty of food choices throughout the growing season.

• Stay away from hybrid and genetically modified plants, which often don’t produce any of the pollen that bees need to survive.

• Never use pesticides or herbicides of any kind. Though these poisons may be meant for plants and non-bee pests, they can often have a “spill-over” effect that harms innocent bystander species, bees among them. (Pesticides are also extremely unhealthy for us land-bound creatures, too!)

• Consider starting a hive and being a beekeeper. The NRDC suggests creating a nest for wood bees (which don’t sting!) by simply taking a non-treated block of wood, drilling holes 3/32 of an inch to 5/16 of an inch in diameter and about 5 inches deep, and leaving it out for bees to find. Traditional beekeeping also has many rewards, from a supply of homemade honey to assured garden pollination.

For more information about CCD, pollinators, and how you can help them, visit the Pollinator Partnership.