January 20, 2010

UK Bee Population Dropping Due To Diet

Research suggests that the decline of honeybees seen in many parts of the world has been caused by the reduction of plant diversity, according to BBC News.

The scientists found that bees fed on pollen from several plants had a healthier immune system than those eating pollen from a single type.

The French team wrote in the journal Biology Letters that bees need a fully functional immune system in order to sterilize food for the colony.

Other research has shown that bees and wild flowers are declining in step.

Scientist reported two years ago that the diversity of bees and other insects were falling along with the diversity of plants that they fed on and pollinated.

Cedric Alaux and colleagues from the French National Institute for Agricultural Research (INRA) in Avignon have traced a possible link between the diversity of bee diets and the strength of their immune system.

"We found that bees fed with a mix of five different pollens had higher levels of glucose oxidase compared to bees fed with pollen from one single type of flower, even if that single flower had a higher protein content," he told BBC News.

Bees produce glucose oxidase (GOX) to preserve honey and food for larvae against infestation by microbes. 

"So that would mean they have better antiseptic protection compared to other bees, and so would be more resistant to pathogen invasion," said Dr Alaux.

Bees that consumed a five-pollen diet produced more fat than those eating only a single variety.

New research from the University of Reading suggests that bee numbers are falling twice as fast in the U.K. than in the rest of Europe.

With the commercial value of bees' pollination estimated at $14 billion in the U.S. alone, governments have recently started investing resources in finding out what is behind the decline.

In some countries it has been blamed on diseases such as Israeli Acute Paralysis Virus (IAPV), infestation with varroa mite, pesticide use, loss of genetic diversity among commercial bee population, and the changing climate are to blame.

The U.S. have seen some of the biggest losses where entire colonies have been wiped out, leading to the term colony collapse disorder.

However, the exact cause of this is still unknown.

New research leads to a possible conclusion that the insects need to eat a variety of proteins in order to synthesize their various chemical defenses.  Without their varied diet they are more prone to disease.

David Aston, a chair holder at the British BeeKeepers' Association technical committee, described the finding as "very interesting," particularly as the diversity of food available to bees has declined.

"If you think about the amount of habitat destruction, the loss of biodiversity, that sort of thing, and the expansion of crops like oilseed rape, you've now got large areas of monoculture; and that's been a fairly major change in what pollinating insects can forage for."

He said that as a consequence, bees often do better in urban areas than in the countryside, because city parks and gardens contain a higher diversity of plant life.

Alaux said while cautioning that laboratory research alone cannot prove the case, the finding tied in well with what is happening in the U.S.

The collapse has been seen in hives that are transported around the country to pollinate commercially important crops.

"They move them for example to [a plantation of] almond trees, and there's just one pollen," he said.

"So it might be possible that the immune system is weakened, compared to wild bees that are much more diverse in what they eat."

The problem may have been compounded by a loss of genetic diversity amongst the bees themselves.

In the U.K., Aston believes there is some scope for turning the trend and giving some diversity back to the foraging bees.

"I'd like to see much greater awareness among land managers such as farmers about managing hedgerows in a more sympathetic way - hedgerows are a resource that's much neglected," he said.

"That makes landscapes much more attractive as well, so it's a win-win situation."


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