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The mysterious collapse of honey-bee colonies is becoming a global phenomenon. Declines in managed bee colonies, seen increasingly in Europe and the US in the past decade, are also now being observed in China and Japan and there are the first signs of African collapses from Egypt, according to the report from the United Nations. Beekeepers in Western countries have been reporting slow declines of stocks for many years, apparently due to impaired protein production, changes in agricultural practice, or unpredictable weather. In early 2007, abnormally high die-offs (30-70% of hives) of European honey bee colonies occurred in the U.S. and Québec; such a decline seems unprecedented in recent history. This has been dubbed Colony collapse disorder (CCD); it is unclear whether this is simply an accelerated phase of the general decline due to more adverse conditions in 2006, or a novel phenomenon. More than a dozen factors, ranging from declines in flowering plants and the use of memory-damaging insecticides to the world-wide spread of pests and air pollution, may be behind the emerging decline of bee colonies across many parts of the globe.
Bees are generalist floral visitors, and will pollinate a large variety of plants, but by no means all plants. Of all the honey bee species, only Apis mellifera has been used extensively for commercial pollination of crops and other plants. The value of these pollination services is commonly measured in the billions of dollars.
Currently being used as pollinators in managed pollination are honey bees, bumblebees, alfalfa leafcutter bees, and orchard mason bees. Humans also can be pollinators, as the gardener who may hand pollinates squash blossoms.
Declines in managed bee colonies date back to the mid 1960s in Europe but have accelerated since 1998, especially in Belgium, France, Germany, Italy, the Netherlands, Spain and the United Kingdom.
In North America, losses of honey bee colonies since 2004 have left the continent with fewer managed pollinators than at any time in the past 50 years.
Chinese bee keepers, who manage both western and eastern species of honey bees, have recently faced several inexplicable and complex symptoms of colony losses in both species.
A quarter of beekeepers in Japan have been confronted with sudden losses of their bee colonies.
In Africa, beekeepers along the Egyptian Nile have been reporting signs of CCD although to date there are no other confirmed reports from the rest of the continent.
There seem to be multiple factors involved in CCD. Habitat degradation, including the loss of flowering plant species that provide food for bees, is among the key factors behind the decline of wild-living pollinators.
An Anglo-Dutch study has found that since the 1980s, there has been a 70 per cent drop in key wild flowers among, for example, the mint, pea and perennial herb families.
Parasites and Pests, such as the well known Varroa mite which feeds on bee fluids, are also a factor.
Other parasites include the small hive beetle, which damages honeycombs, stored honey and pollen. Endemic to sub-Saharan Africa, it has spread to North America and Australia and may come to Europe.
Bees may also be suffering from competition by ‘alien species’ such as the Africanized bee in the United States and the Asian hornet which feed on European honey bees. The hornet has now colonized nearly half of France since 2004.
Air pollution may be interfering with the ability of bees to find flowering plants and thus food.
Electromagnetic fields from sources such as power lines might also be changing bee behavior. Bees are sensitive as they have small abdominal crystals that contain lead.
Herbicides and pesticides may be reducing the availability of wild flowers and plants needed for food and for the larval stages of some pollinators. Laboratory studies have found that some insecticides and fungicides can act together to be 1,000 times more toxic to bees.
Some insecticides, including those applied to seeds and which can migrate to the entire plant as it grows, and others used to treat cats, fish, birds and rabbits, may also be taking their toll.
Studies have shown that such chemicals can affect the sense of direction, memory and brain metabolism in bees
The management of hives may also be adding to the problem. Some of the treatments against pests may actually be harmful to bees and a growing habit of re-using equipment and food from dead colonies might be spreading disease and chemicals to new hives.
Transporting bees from one farm to another in order to provide pollination services increasingly unavailable from nature could be an additional factor. In the United States, trucks carrying up to 20 million bees are common and each year over two million colonies travel across the continent. Mortality rates, following transportation, can be as much as 10 per cent of a colony
The full report, Global Bee Colony Disorders and other Threats to Insect Pollinators, can be downloaded at:
: Honeybee End?.