This might be the bees' worst enemy
The small Varroa destructor mite is the biggest threat to Australia's population of bees.PT0M0S 620 349
''If the bee disappears from the surface of the Earth, man would have no more than four years to live,'' Albert Einstein once said, referring mainly to honeybees pollinating the flowers of at least a third of the wild and farmed plants that humans eat.
Although bees have not disappeared yet, the insects that collect nectar and pollen and make honey and wax are in precipitous decline: populations in the US and Britain, for example, have halved over the past 25 years.
Reasons for the decline range from the prevalence of chemicals, particularly common crop pesticides, to the destruction of flower-rich habitats and the rise in electromagnetic radiation from mobile telephone towers and transmission lines.
The biggest pest threat is from the evil-sounding Varroa destructor, an oval-shaped, reddish-brown mite that sucks the blood from bees and transmits virulent diseases, such as deformed-wing virus.
The pinhead-sized bloodsuckers have decimated bee populations worldwide, including in neighbouring New Zealand and Papua New Guinea, but have not arrived yet in Australia.
''If they enter this country, the mites will completely wipe out our wild honeybees, which means crop growers will lose their largest and free source of pollination, worth more than $1 billion a year,'' says bee pathologist Denis Anderson of CSIRO Ecosystem Sciences in Canberra.
The mites will also reduce the number of managed honeybee colonies, he explains. ''This means keepers will pay more for scarce paid pollination services — costs that would flow through to consumers.'' In addition, most of Australia's horticultural and agricultural crops, worth billions of dollars, rely on bees for pollination.
That Australia is one of very few countries to remain free of the dreaded mite is the result of good luck and good management, Dr Anderson says. ''Varroa mites could enter the country in a variety of ways and, on several occasions, our quarantine authorities have been lucky to intercept them before they got through.''
Despite efforts to tighten quarantine controls, Dr Anderson believes it is inevitable that the mites will get into Australia. So the race is on to find revolutionary ways of disabling them before they wreak havoc on wild and domestic bee strains.
Among other things, Dr Anderson and colleagues have been sequencing the mite's genome, or genetic make-up.
''Biotechnology can knock out critical genes that the mite needs for its survival. If this is achieved, then control might be possible,'' he explains. ''Our work could assist research being carried out in Britain on a shoestring budget, which is still a long way from completion.''
Once the genome sequence is complete, researchers will create and scour databases of all the Varroa genes in a bid to identify those that can be used to disable the mites before they do their damage.
Looking for exotics
While the hunt is on for ways to halt the mite in its tracks, scientists want to improve quarantine procedures.
Australia's national port surveillance program, although currently inadequate to deal with the threat, is being strengthened. Surveillance for honeybees and bee pests and parasites that are exotic to Australia forms part of the national sentinel hive program, which is co-ordinated by Plant Health Australia.
The program, established in 2000, has been growing steadily, Dr Anderson says. ''It operates on the premise that most of the important exotic pests and parasites will enter Australia on live honeybees from another country — particularly through bee swarms arriving on vessels at our sea ports,'' he explains.
An exotic swarm arriving this way could, if it went unnoticed, swarm off the vessel and set up home on land. ''If it was a swarm of European honeybees, then it would be impossible to tell apart from our local European bees,'' he points out. ''If the swarm was carrying exotic parasites, such as the Varroa mite, those parasites would spread to colonies near the port, and then on to colonies further away.''
The national sentinel hive program places special hives at sea ports around Australia and monitors them every two months for signs of exotic pests and parasites that may have arrived in a bee swarm from overseas.
The program's success depends on how many hives are at each port and the number of ports targeted. ''The more of each, the higher the chance of success,'' he says. ''At present, only a few hives are based at a few strategic ports — just three hives cover Melbourne and Geelong, for example — and there are not enough funds to expand the current program.''
This is why the state government has set up Bee Force, a pilot project to improve Victoria's capacity to detect incursions of exotic bee pests. Now on trial in Melbourne and Geelong, the project involves local amateur beekeepers who run sentinel hives.
''This encourages community involvement and expands the number of sentinel hives that can be used for surveillance, thus keeping costs to manageable levels,'' Dr Anderson says. ''If the trial Bee Force program proves successful, it could be extended to other port areas.''
Victoria's Department of Primary Industries has trained a honeybee state quarantine response team of 90 beekeepers, including hobby and commercial beekeepers, who may be called on to assist in an emergency.
The early detection of the Varroa mite, combined with effective surveillance, it is argued, may increase the chance of eradicating the parasite once it enters the country. This has never been achieved before.
The Livestock Disease Control Act (1994) requires beekeepers who suspect Varroa mites are present in their apiaries, to notify a government apiary, animal health or veterinary officer. They can do this by calling the disease watch hotline on 1800 675 888.
Until an officer arrives, beekeepers are advised to take steps to reduce the risk of spread.
A short history of mites
In the late 1970s and early 1980s, colonies of the Asian hive bee and the European honeybee were introduced to Irian Jaya from Java. The Asian bees brought with them a parasitic mite similar to Varroa, as did the European honeybees.
It was feared that the mites would eventually spread to the main beekeeping areas of Papua New Guinea and destroy the nation's fledgling bee industry; additionally it was believed that the mites could island-hop through the Torres Strait to Australia.
The Varroa mite is relatively harmless to its original native host, the Asian honeybee. The mite switched host to the European honeybee during the mid-1900s when the bee was introduced into Asia.
''Since it switched host, the mite has spread throughout the world,'' Dr Anderson says. ''Let's ensure we do everything possible to keep the parasite out of Australia for as long as we possibly can.''
At 2pm today, IMAX Melbourne's schools education program will screen the live-action nature movie Bugs 3D, shot on location in Borneo and in a purpose-built studio in Britain. Details here.
Learn more about the pernicious Varroa mite and the way it attacks bees here.
Check out the research article ''Genomic survey of the ectoparasitic mite Varroa destructor, a major pest of the honey bee Apis mellifera'' here.
To find out why introduced species can become so destructive in new areas, read the article ''Can behavioral and personality traits influence the success of unintentional species introductions?'' by David Chapple, Sarah Simmonds and Bob Wong here.
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