Getting the buzz on the value of bees
Box 4 | Fighting the Varroa mite
impact, control and biology of the Varroa mite. (Credit: Denis Anderson,
CSIRO Entomology.)
Australia is the only major country left in the world without Varroa mites. Luckily however, Australian scientist Denis Anderson and his CSIRO team in Canberra are world leaders when it comes to understanding these deadly bee parasites.
Since discovering and naming the mite Varroa destructor in 2000, Dr Anderson and his team have discovered that the larvae of European honeybees emit a chemical signal that can be detected by the Varroa destructor. (Asian honeybee worker larvae do not emit this signal and so Asian honeybee workers are not affected by the mite). The group is therefore looking for ways to mask or alter the chemical signal, thus preventing it from inciting the mite to invade. Dr Anderson thinks that the European honeybee genome, which was sequenced recently, could hold the key – if the gene responsible can be identified, perhaps it can be ‘turned off’.
DNA Varroa mite extractions.
(Credit: John Roberts, CSIRO.)
Varroa could pose a double-barrelled problem, however. The natural host of the other problematic Varroa mite, V. jacobsoni, is a strain of the Asian honeybee found in the Indonesian island of Java. This mite was completely unknown until Dr Anderson discovered that colonies of European honeybees in Papua New Guinea were dying as a result of a V. jacobsoni infestation – it may turn out to be just as deadly to the European honeybee as V. destructor. Dr Anderson’s colleague John Roberts is investigating how and when V. jacobsoni transferred to the European honeybee with a view to increasing an understanding of the mechanisms involved. Was it a gradual adaptation, meaning that V. jacobsoni mites are now able to survive off the European honeybee, or did only one or a few individuals with the ‘right’ genetic make-up jump from one host to the other as was the case for V. destructor? The answer is crucial to Australia in terms of assessing our risk should V. jacobsoni arrive, and in preparing adequate defences against its possible incursion. The CSIRO team is also investigating the viruses and other pathogens hosted by V. jacobsoni to determine the risk they might pose to the European honeybee.
Researchers in Western Australia and Sydney, including Ben Oldroyd, are also tackling the Varroa issue from another perspective. The team is sending queen bees from the Western Australian bee breeding program to researchers in the United States to test their tolerance against the Varroa mite. Resistant strains could help to avert the worst effects of the mite and put Australia in a stronger position to deal with a Varroa outbreak, should it manage to breach our borders.
For more information about Varroa see Further Reading and Useful Sites (which also includes numerous short films about the Varroa mite and the research of Dr Denis Anderson).
Boxes
Box 1. Native bees
Box 2. Epigenetics
Box 3. Ensuring sufficient pollinators
Related sites
Dr Denis Anderson's home page Varroa destructor Anderson & Trueman, 2000
Raising the alarm on bee biosecurity, 2006
The sting, 2001
See also numerous other articles and short movie clips about Varroa (including the documentaries Honeybee Blues and Bee Afraid) listed under Further Reading and Useful Sites.
External sites are not endorsed by the Australian Academy of Science.
Posted August 2011.