Jan 5, 2011
Plight of the bumblebee
Study highlights impact of species wipe-out from inbreeding and disease
WASHINGTON: Weakened by inbreeding and disease, bumblebees have died off at an astonishing rate over the past 20 years, with some US species diving by more than 90 per cent, says a study.
The findings are of concern because bees play a crucial role in pollinating crops such as tomatoes, peppers and berries, according to a three-year study published on Monday in the Proceedings of the National Academy of Sciences.
Similar declines have also been seen in Europe and Asia, said Ms Sydney Cameron, the main author of the study.
It linked the bumblebee decline in the United States to a lack of genetic diversity which might make them vulnerable to a disease-causing pathogen called the Nosema bombi, which has also afflicted European bumblebees.
Ms Cameron, of the Department of Entomology and the Institute for Genomic Biology at the University of Illinois, said the decline is 'huge and recent', having taken place in the last two decades.
But she said the study could not definitely conclude that Nosema bombi was responsible for killing off bumblebees.
'It's just an association. There may be other causes,' she said.
Researchers examined eight species of North American bumblebees and found the relative abundance of four species had dropped by more than 90 per cent.
Their cousins, the honey bees, have also experienced catastrophic die-offs since 2006 in a phenomenon known as 'colony collapse disorder', though the causes have yet to be fully determined. Scientists from the US Department of Agriculture said the pathogens to blame are a fungus and a family of viruses, according to BBC News.
Bumblebees also make honey, but it is used to feed the colony, not farmed for human consumption.
They are, however, raised in Europe to pollinate greenhouse vegetables in a multibillion-dollar industry that has more recently taken off in Japan and Israel and is being developed in Mexico and China, Ms Cameron said.
'We need to start to develop other bees for pollination besides honey bees because they are suffering enormously,' she added.
There are around 250 species of bumblebees, including 50 in the US alone.
Last September, a study carried out by Scottish scientists suggested that some of Britain's rarest bumblebees were at risk of becoming extinct as a result of inbreeding and increased susceptibility to parasitic infection, according to BBC News.
AGENCE FRANCE-PRESSE
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