Beekeepers on high alert as bee-killing varroa mite spreads in South Australia
Beekeepers are encouraged to remain vigilant as more varroa mite detections are made throughout South Australia. (ABC News: Emma Masters)
In short:
Varroa destructor, commonly known as varroa mite, was first discovered in a beehive in South Australia's Riverland in September and has since been found in other areas across the state.
The tiny mites can kill honey bee colonies and transmit numerous viruses to their hosts.
What's next?
Beekeepers are being urged to regularly monitor their hives.
They are smaller than a sesame seed but the bee-killing parasite known as varroa destructor lives up to its name, with a huge capacity to decimate beehives if left untreated.
First detected in South Australia's Riverland region in September, the varroa mite has since been found in numerous sites across the state, including the Limestone Coast, the Adelaide Hills and the Fleurieu Peninsula.
The number of detections has increased in recent weeks.
President of the Beekeepers Society of SA, Bob Beer, said everyone was on high alert.
"The mite's move into the state has always been a case of not if, but when," he said.
"None of us have been looking forward to the time when varroa comes because we've seen the repercussions that have happened in other countries; the devastation, the loss of hives, the loss of production, the loss of pollination.
"It's almost a case of saying there's nothing you can do to prevent it from getting in because the mite travels on the bee and and bees are going to infest other hives from feral colonies or from neighbouring hives."
Beekeepers like Josh Ambrosio (left) and Bob Beer are urging their peers to be vigilant about the spread of varroa mite. (ABC News: Emma Masters)
As beekeepers adjust to their new normal, the society said its members needed to be extra vigilant.
It has been busy encouraging beekeepers to boost monitoring of hives and to consider additional methods to quell the mites' ability to infest hives.
"Unless you monitor, you're not going to know that you've got it. It's as simple as that," Mr Beer said.
"And by beekeepers monitoring, we're going to keep a much better record for the benefit of all concerned, especially the industry."
The society has been holding regular demonstration sessions on how to check hives.
The process involves 'washing' — collecting bees in a jar filled with a solution of either alcohol or detergent.
Once half a cup of bees, which is generally about 300 insects, are added to the jar, it is vigorously shaken then checked to see if mites have fallen off the bee and into the solution.
Bob Beer separates the queen bee from the hive and marks its back with a texta. (ABC News: Emma Masters)
The shake and check process is repeated a number of times.
The general rule is that if more than nine mites are found in a solution of around 300 bees, the state government advises it be treated.
Josh D'Ambrosio is a longtime beekeeper and one of three varroa development officers now employed at SA's Department of Primary Industries.
He said infested hives would not be destroyed in the way they were interstate when the parasite first arrived in Australia, explaining that eradication has since been abandoned and a management approach has been adopted across the country.
"Left untreated it [varroa mite] will basically cause that colony to collapse and die out. But it is manageable,"he said.
"A number of treatments are available, both mechanical and obviously chemical."
Varroa mite is spreading through hives in South Australia. (ABC News: Emma Masters)
The South Australian government wants beekeepers within 25 kilometres of sites where the parasite has been found to significantly increase hive monitoring to once every few weeks.
"We don't want surprises. We don't want beekeepers to go to their hives and do a monitoring wash and find hundreds and hundreds of mites," Mr D'Ambrosio said.
"We want beekeepers to be monitoring when they don't have mites. So they're identifying the arrival of mites within their apiaries."
He said there were still a number of unanswered questions about how varroa would respond in the local environment.
"In South Australia we have a lot of microclimates, so the way varroa might react within those environments is unknown," Mr D'Ambrosio said.
"It is going to be a process of understanding and working our way through.
"We have evidence that we can draw upon from interstate with New South Wales, Victoria, Queensland, ACT as well as evidence and experience from overseas."
Josh Ambrosio (left) and Bob Beer (right) smoke the bees before checking for varroa mite. (ABC News: Emma Masters)
Impact on feral hives
One thing that is known is the devastation the varroa mite will cause among wild, feral bee colonies.
"We expect to lose 95 per cent, if not more, of the feral bee population, and then management of the varroa is going to become a lot more predictable," Mr D'Ambrosio said.
"A lot of our pollinated-dependent industries rely on honey bees for their produce. So things like apple, pears, almonds … cherries, berries.
"And a lot of those growers are very much dependent on a lot of that natural pollination."
Mr D'Ambrosio said the loss of feral hives would mean a greater demand for managed beehives.
"So there is an opportunity for beekeepers to manage hives … and working with beekeepers to assist with pollination on a larger scale is an opportunity," he said.
Varroa mites have caused huge problems for bee colonies. (Supplied: Australian Honey Bee Industry Council)
But there is a risk some will leave the industry.
"We do expect to see up to a 40 per cent, if not greater, decline in beekeeper numbers, as we see beekeepers moving out of the industry," Mr D'Ambrosio said.
"So that's a factor we need to consider because we don't want to see too much of a decline for hives for pollination."
Protecting hives
Mr Beer said he was doing what he could to protect his hives, including installing ventilated floors, so he could keep doing what he loved.
"We understand that by having ventilated floors there's the potential of losing anything up to 20 per cent of your mites because the bees are grooming themselves and so they're going to dislodge mites … and they'll fall through the floor of the hive," he said.
Varroa mite has been detected in several hives around South Australia. (ABC News: Emma Masters)
He is also looking at using drone brood, which mites prefer over worker bees because they have a longer gestation period.
"The mite can determine the difference between a worker cell and a drone cell," he explained.
"It's creating a trap that's going to entice the mite to come in and lay and then you take that frame out before that laying cycle of eggs are ready to hatch … put it in the freezer and kill it.
He said he would keep looking at ways to protect his hives.
"I seriously want to continue to keep bees, I want to harvest my own honey and so it's going to be a learning experience," he said.