Have scientists solved the mystery of dying bees? Hives exposed to insecticide ARE more likely to suffer colony collapse
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Scientists have warned that the collapse of bee colonies could trigger a farming crisis, but why populations are being hit so hard has remained largely a mystery.
Now one group of experts has proved that two widely used neonicotinoids - a class of insecticide – harm honeybee colonies over the winter, particularly when temperatures drop.
Research revealed that even low doses of an insecticide called clothianidin had an adverse effect on hives.
Horror at the hive: One group of experts have proved that two widely used neonicotinoids - a class of insecticide - harm honey bee colonies (pictured) over the winter, particularly when temperatures drop
HONEYBEE SHORTAGE COULD COST THE UK ECONOMY £1.8BN, CLAIM SCIENTISTS
There are only enough honeybees in Britain to properly pollinate a quarter of the country's crops, scientists claim.
Destruction of huge swathes of grassland and the use of agricultural chemicals have caused a spiralling drop in the populations of honeybees, which are vital for food production.
Professor Simon Potts of the University of Reading, who led the research project, said: 'We face a catastrophe in future years unless we act now.'
The research, published in the journal PLOS One, found that Europe has 13.4million too few honeybee colonies to properly pollinate all its crops.
Bee populations have plummeted as their meadowland habitats were concreted over and their wildflower food supply killed by herbicides.
Previous studies have estimated that the number of British honeybees have halved over the last 25 years.
Scientists think the bee shortfall is leading to reduced crop yields and they warn that in future farmers may have to look at mechanical or hand pollination.
The study by the Harvard School of Public Health (HSPH) in Cambridge, Massachusetts, strengthens the scientists' findings from last year that low doses of imidacloprid - another neonicotinoid - are linked to colony collapse disorder (CCD) where bees abandon their hives over the winter and eventually die.
Although other studies have suggested that CCD-related mortality in honeybee colonies may come from bees' reduced resistance to mites or parasites as a result of exposure to pesticides, the new study found that bees in the hives exhibiting CCD had almost identical levels of pathogen infestation as a group of control hives, most of which survived the winter.
This finding suggests that the neonicotinoids are causing some other kind of biological mechanism in bees that in turn leads to CCD, according to the study, published in the Bulletin of Insectology.
'We demonstrated again in this study that neonicotinoids are highly likely to be responsible for triggering CCD in honeybee hives that were healthy prior to the arrival of winter,' said lead author Chensheng (Alex) Lu, associate professor of environmental exposure biology at HSPH.
Putting the pest in pesticide: Research revealed that even low doses of an insecticide called clothianidin had an adverse effect on the hives. It has previously been found that low doses of imidacloprid are linked to colony collapse disorder (CCD) where bees abandon their hives over the winter and eventually die
Since 2006, there have been significant losses of honeybees from CCD. Pinpointing the cause is crucial to mitigating this problem since bees are prime pollinators of roughly one-third of all crops worldwide.
Experts have considered a number of possible causes, including pathogen infestation, beekeeping practices, and pesticide exposure.
Recent findings suggest that CCD is related specifically to neonicotinoids including imidacloprid and clothianidin, which may impair bees' neurological functions.
Together with experts from the Worcester County Beekeepers Association, the scientists studied the health of 18 honeybee colonies in three locations in central Massachusetts between October 2012 and April 2013.
At each location, the researchers separated six colonies into three groups -one treated with imidacloprid, one with clothianidin and one untreated.
There was a steady decline in the size of all the bee colonies at the beginning of winter, which is typical among hives during the colder months in New England.
The battle bee-gins: Since 2006, there have been significant losses of honey bees (pictured) from CCD. Pinpointing the cause is crucial to mitigating this problem since bees are prime pollinators of roughly one-third of all crops worldwide
Beginning in January 2013, honeybee populations in the control colonies began to increase as expected, but populations in the neonicotinoid-treated hives continued to decline.
By April 2013, half of the neonicotinoid-treated colonies were lost with abandoned hives that are typical of CCD.
While the 12 pesticide-treated hives in the current study experienced a 50 per cent CCD mortality rate, the authors noted that in their 2012 study, bees in pesticide-treated hives had a much higher CCD mortality rate of 94 per cent.
That earlier bee die-off occurred during the particularly cold and prolonged winter of 2010-2011, leading the authors to speculate that colder temperatures, in combination with neonicotinoids, may play a role in the severity of CCD.
'Although we have demonstrated the validity of the association between neonicotinoids and CCD in this study, future research could help elucidate the biological mechanism that is responsible for linking sub-lethal neonicotinoid exposures to CCD,' said Professor Lu.
'Hopefully we can reverse the continuing trend of honeybee loss.'
PREVIOUSLY 5,000 HONEYBEES HAVE BEEN FITTED WITH SENSOR 'BACKPACKS' TO HELP SCIENTISTS UNDERSTAND WHY COLONIES ARE DYING
In a bid to stop the rapid decline, experts fitted 'backpack' sensors to 5,000 bees in Australia in January to unravel why colonies there do not seem to be affected by the 'colony collapse disorder' that is decimating bee populations in other countries.
The research aims to improve honey bee pollination and productivity on farms as well.
Scientists at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) fitted 5,000 tiny sensors, measuring just 2.5mm squared to the backs of honeybees in Hobart, Tasmania, before releasing them into the wild.
It is the first time such large numbers of insects have been used for environmental monitoring.
'Honeybees play a vital role in the landscape through a free pollination service for agriculture, which various crops rely on to increase yields' said CSIRO science leader Dr Paulo de Souza, who is heading up the swarm sensing project.
'A recent CSIRO study showed bee pollination in Faba beans can lead to a productivity increase of 17 per cent.
'Around one third of the food we eat relies on pollination, but honeybee populations around the world are crashing because of the dreaded Varroa mite and Colony Collapse Disorder.
The research will also look at the impacts of agricultural pesticides on honeybees by monitoring insects that feed at sites with trace amounts of commonly used chemicals.
Scientists at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) have fitted 5,000 tiny sensors, measuring just 2.5mm squared to the backs of honey bees in Hobart, Tasmania, before releasing them into the wild
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