It is a survival story worthy of a Hollywood blockbuster — a single Asian honey bee queen, stranded in Australia with nothing but her loyal workers, fights to survive.
In a foreign environment, she somehow flourishes, and the swarm grows into as many as 50,000 bee colonies across north Queensland.
While a pest incursion would ordinarily be considered an invasive species disaster, how these bees defied the odds could instead prove to be the saviour of native species on the brink of extinction.
But — like with any good story — the plot is complex, and this one could still have a sting in the tail for biodiversity.
Stowaway success
The story opens with a flashback to 2007, to the busy Port of Cairns, where cargo ships, cruise liners and fishing fleets come and go.
Among them is a ship from Papua New Guinea, harbouring the queen and her stowaway swarm of Apis cerana — popularly known as Asian honey bees.
Only a few make it to shore, and without the genetic diversity to breed a strong colony, they should die out quickly.
But instead, over the next 17 years, they thrive, and the bees are now found in trees, homes, letterboxes and compost bins from Wonga Beach to Cardwell and to the Atherton Tablelands.
Their success poses a major risk to native bee populations as well as the honey and pollination industries but also presents an opportunity to learn more about adaptation and evolution.
Breaking out of the bottleneck
What the bees went through is called a genetic bottleneck, where a species population shrinks dramatically then significantly increases.
Research fellow Ros Gloag, who lectures in evolutionary biology at the University of Sydney, studied the bees’ survival.
“Having genetic diversity in a population is important for its adaptive response, its resilience to environmental changes,” Dr Gloag said.
“Because natural selection acts on the variation that’s within a population.”
The bigger the population, the more chance the genes of bees that have adapted to their environment will be naturally selected to pass on to future generations.
Even though the genetic diversity of the bees in Australia was significantly lower than in their home in south-east Asia, Dr Gloag said there was enough for natural selection to work.
“Maybe we do underestimate just how powerful natural selection can be in getting populations to respond even when a lot of genetic diversity is gone,” she said.
Dr Gloag said the study revealed the population had likely adapted their reproduction and foraging behaviour on a genetic level.
And if they could do it, it may mean threatened native species may be able to do it, too.
Evil queen plot twist
The story of an invasive species thriving in Australia is not a hero’s tale, even if it might help native species.
The pests are a threat to both native bees and the European species (Apis mellifera) relied on for honey and the pollination of crops.
Dr Gloag said the two species had been observed trying to cross-breed and while it was rare, there were risks.
“That’s what we call reproductive interference … they try to hybridise with each other, even though they can’t,” she said.
“[It can] transfer pests, pathogens and diseases.”
One such pest is the varroa jacobsoni mite, which was detected at the Brisbane port in Queensland this week.
A different species of mite to the varroa destructor that has plagued New South Wales and Victoria’s honey industry, its preferred host is the Asian honey bee.
Australian Honey Bee Industry Council chief executive Danny Le Feurve said the detection of the single mite was concerning.
“It’s just another blow for our industry … another detection of a pest that we don’t want,” he said.
Around the port, the bee industry is in lockdown as Biosecurity Queensland investigates if the mite was carrying other viruses or pests, where it came from, and if it spread.
From there, authorities will decide if it is possible eradicate the mite to once again.
Shown to jump between bee species, Mr Le Feurve was hopeful the mite would not be a significant issue for apiarists.
“The single mite was found in a European honey bee colony, so that is alarming,” Mr Le Feurve said.
“But to date, there hasn’t been a huge impact from varroa jacobsoni globally on European honey bees.”
The detection site is about 1,500 kilometres away from the nearest Asian honey bee outbreak in north Queensland, and there was little chance the two would meet.
With low genetic diversity comes reduced queen fertility, which Dr Gloag said led to “dud” male workers that made it hard for the bees to migrate far.
“It’s a really dense population in a small area,” she said.
“It has trouble colonising beyond its existing range.”
But there was already a sequel in the works, with Dr Gloag’s team now studying the aftermath of the genetic bottleneck and what it means for the next evolution of this invasive population.
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