We’d be hard
pressed in this office to pick up a journal aimed at beekeepers, without
reading an article on Colony Collapse Disorder (CCD); a disaster that has taken
the bee world by storm. Writing in the September/October 2008 issue of The IPM
Practitioner, William Quarles reviews pesticides and CCD.
Since its
documented discovery in November 2006, there has been much discussion as to the
cause(s) of this phenomenon, and not least the implication of pesticide use. In
Quarles' article, the abstract of which can be found in CAB Abstracts, we are
told that under normal circumstances, about 15-25% of bee colonies die due to
overwintering stress, including starvation. However, some beekeepers reported
losses of 30-90% in the winter of 2006-2007. Dead bees were not found in or by
the hives, but they just disappeared.
The symptoms of CCD as listed by Quarles include:
- Foraging
adults leave the hive and do not return
- Decline is fast, with colonies shifting from large and strong to
dead within a matter of months, with no sign of mite infestation
- Dead bees are not found in or around the hive
- Adult bees that are left show signs of a depressed immune system
- Queen and seemingly healthy brood can be found in the hive
- Bees that are nearby, wait weeks before entering the hive for food
- Delayed entry is also seen among predators such as the small hive
beetle or wax moth
- When a dead hive is placed on top of a healthy one, and the healthy bees are forced to enter the hive, those bees also disappear.
The exact cause of
CCD is unknown, but there are a number of possible culprits, as identified in
the USDA's CCD Research
Action Plan, namely new or re-emerging pathogens, new bee pests or
parasites, environmental and/or nutritional stresses or pesticides. However,
pathogen attacks are not in keeping with the symptoms of CCD because bees
infected with pathogens are thrown out of the hive by housekeeping bees. Death
by mites is also well-characterized and bees surviving from CCD do not show
mite infestations (Quarles, 2008).
Which brings me on
to pesticides and an interesting observation that ‘seems to implicate pesticides
[as a cause of CCD] is that organic beekeepers do not seem to have CCD’
(Schaker, 2008). So, a recent BCPC press
release with the title ‘Banning insecticides will not save British bees’,
certainly got my attention.
On 28 January, the Co-op launched Plan Bee, which prohibits suppliers of its own-brand fresh produce from using neonicotinoid insecticides until they are found to be safe to honeybees. The Guardian covered this launch here. BCPC chairman, Dr Colin Ruscoe was quoted in the BCPC press release as saying “This is just another example of organisations reacting in an emotive area without reference to the science base. The well-documented decline in honeybee populations is a complex problem. Losses are due to a combination of issues, weather, the Varroa mite and other factors which require further research. That is why Defra is putting an extra £4.3 m of funding into bee health research”.
The debate and
research continue……...
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