News

Research confirms catastrophic effects of Varroa mite on Aussie bees



25 June 2012

The worst fears of Australia's honeybee industry have been realised, with new research confirming that Australian honeybees are highly susceptible to a pest that hasn't yet reached our shores but will decimate them when it does.

The exotic Varroa mite (Varroa destructor) is present in all beekeeping countries worldwide, except Australia. The size of a sesame seed, Varroa mites attach themselves to bees and suck their blood, leaving them more susceptible to disease. Where Varroa is present it devastates beehives and requires intensive treatment with miticides to control it.

US Department of Agriculture field trials
US Department of Agriculture field trials

A research project carried out jointly by the University of Sydney and the United States Department of Agriculture Agricultural Research Service and funded by the Rural Industries R&D Corporation evaluated seven lines of Australian bees and found that none had any resistance to the Varroa mite. The research confirmed that an incursion of the pest would have catastrophic effects on bee populations and those industries that rely on them for pollination.

Major crops, like almond, apple, avocado, blueberry and cucumber rely heavily on bees for pollination.

The research project compared the responses of the Australian honeybees to a Varroa infestation with the responses of US Italian honeybees that are known to be susceptible to the mite and two other types of honeybee known for their resistance to Varroa.

After only four months of exposure to the Varroa mite 44 percent of all the Australian honeybee lines had died. This compared to a 4 percent mortality rate over the same period for the most resistant Russian honeybee, which isn't found in Australia.

Professor Ben Oldroyd of the University of Sydney said the research provides a clearer picture on the potential impacts of a Varroa incursion in Australia.

"It is largely accepted that Varroa will eventually reach Australia and the findings from our research give us an indication of just how severe an impact this pest will have on our honeybee populations," Professor Oldroyd said.

"Because Australian honeybees have never been exposed to Varroa the chances of them being susceptible are much greater.

"If there was a positive to take out of this research it is that it showed there are breeds of bees that do have a considerable resistance to Varroa, however these bees aren't currently found in Australia.

"If the Australian honeybee industry and honeybee dependent crops are to have any chance of minimising the impact of Varroa when it arrives then it is critical that Varroa-resistant honeybees are bred for the Australian environment, and urgently."

A two page summary of the research project can be found on the RIRDC website at www.rirdc.gov.au.