A new unexplained disease is supposedly laying waste to honeybees in the United States, but one of the world’s leading bee pathologists, CSIRO’s Dr Denis Anderson, is yet to be convinced that it’s actually happening.
Dr Anderson is a leading expert on a tangible bee threat, the varroa mite, but the well-travelled scientist can’t buy into the story of Colony Collapse Disorder (CCD), the malaise that is supposedly behind the death of up to a third of US honeybee hives last winter.
“CCD is a recently invented term for an old disorder: winter losses,” Dr Anderson suggested.
“And we all know that losses over winter are due to a range of factors, from varroa to nutrition and management.”
Commercial beekeepers in the US have always accepted winter losses of 10-20 per cent, Dr Anderson said. Bees die in times of hardship, like everything else.
The difference is that since the alarm was raised about bee deaths in 2006-07, and CCD was employed as a cover-all term for the issue, detailed statistics have been recorded on losses.
Dr Anderson has some issues with this.
One is that deaths from hives maintained by amateur beekeepers are being lumped in with hives kept by professionals. Amateurs tend to have higher losses because their hives are less closely managed.
Another is the question of baseline. For the last few years bee death statistics have been used as evidence for the presence of CCD—but Dr Anderson points out that prior to 2007, statistics on honeybees were less rigorously maintained, so there is no firm basis for comparison.
He is also wary of the fact that the CCD surveys in the US are being conducted by the same research agencies that are receiving funding to investigate CCD. “It’s a bit like putting a politician in charge of their own popularity polling,” he said.
His own view is that CCD is being inappropriately being applied as a single symptom to hive failures that are in reality caused by a range of different challenges.
“We need to get rid of the term ‘CCD’ and deal with each event as a separate issue,” Dr Anderson said.
“There are enough problems out there for bees—no need to invent another one.”
In this, Dr Anderson is in accord with bee researchers, pro-CCD or not.
US researchers investigating the CCD phenomenon acknowledge that it doesn’t appear to have a single cause, and no single cause has emerged as being more likely than another.
The United Kingdom’s National Bee Unit has investigated winter bee deaths, and concluded that the UK doesn’t have CCD but is losing bees for a range of other reasons.
Pesticides are a frequently-cited potential culprit in CCD. In Dr Anderson’s view pesticide exposure was possibly behind the intial CCD alarm raised in 2006 by a Pennsylvania apiarist.
He has met the apiarist, who again made the news in reports of 2010 bee losses, and notes that he hasn’t moved his hives from the area where the initial losses were incurred.
A US study published last month found that American bees carry a high load of pesticide and metabolite traces: 121 different chemicals were found in 900 hive samples.
But the authors still warned against jumping to conclusions.
“While exposure to many of these neurotoxicants elicits acute and sublethal reductions in honey bee fitness, the effects of these materials in combinations and their direct association with CCD or declining bee health remains to be determined,” they wrote.
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