The honey bee-killing parasite Varroa destructor has been spreading across New South Wales and the ACT since it was first detected in February 2022.
In that time, the varroa mite has collapsed heavily infected European honey bee hives throughout the region.
Vital for honey production and also playing an important role in pollination of crops, Australia's honey bee industry is estimated to be worth more than $14 billion.
If allowed to spread nationally, the varroa mite could cost the industry $70 million a year, federal Agriculture Minister Murray Watt has predicted.
Other states and territories are now scrambling to contain the mite's spread out of NSW.
What is Varroa destructor?
Varroa destructor, also known as the varroa mite, is a flat, button-shaped parasite which attaches to the bodies of honey bees — and then eats them alive.
The 1 to 2-millimetre-long mites feed on their host bee and on bee larvae until the bee is unable to sustain the mite — either due to infection from the open wounds left by the mite, or due to the mite having eaten vital body parts.
Varroa destructor also spreads at least five debilitating bee viruses, including the deformed wing virus, further weakening the colonies it invades.
After weakening their host, they will transfer to another bee or to another part of the colony they've invaded.
Female varroa mites, identifiable by their red colour, will lay eggs in the honey bee colony's brood cells. Male mites, which are translucent or white, stay in the larvae-rich brood cell to mate.
This is how the mites take over a colony: by literally eating the new generation.
Varroa destructor takes over multiple colonies when host bees travel, and a mite can transfer to a bee from a separate colony.
How does it affect Australian hives?
The varroa mite has spread to several continents from its original home in Asia, but it wasn't detected in Australia until February 2022.
It preys on Apis cerana, the Asian honey bee, as well as Apis mellifera, the European honey bee.
Although the varroa mite cannot attack Australian native bees directly, commercial honey production in Australia is dominated by European honey bees.
European honey bees in Australia contribute about 37,000 tonnes of honey a year.
As the varroa mite evolved to live in temperate climates, beekeepers in temperate zones across Australia have been bracing for a similar impact to the Varroa destructor invasions already seen in the United Kingdom and United States.
In the US, 30 per cent of commercial honey bee hives collapsed after varroa mites became established.
In the UK, 90 per cent of feral honey bee hives — colonies of non-native honey bees established independently to beekeepers — collapsed due to the mite.
According to the agency managing New Zealand's National American Foulbrood Pest Management Plan, feral honey bee colonies are at greater risk of varroa mite infection than managed colonies because beekeepers can successfully manage infection in their own colonies.
Australia's temperate zones are located in NSW, the ACT, Victoria, Tasmania, and small parts of South Australia, Western Australia, and Queensland.
A 2022 study in the journal Ecological Indicators suggested infestation rates were lower in tropical areas compared to temperate ones. It recommended keeping hives at temperatures higher than 25 degrees Celsius, giving hope for Australian beekeepers in warmer states.
Varroa mite established in NSW
Varroa mite was first detected in NSW sentinel hives in June 2022, sparking an eradication effort which lasted 15 months before being scrapped.
Sydney and Newcastle are the most affected regions, followed by the nearby Morisset, Medowie and Heathcote.
Authorities have now given up trying to eradicate the mites, instead shifting to a containment strategy.
The National Varroa Mite Response Plan was approved earlier this year. This new plan emphasises containment and training over eradication.
In May, the NSW Department of Primary Industries announced it would further scrap efforts to eliminate the mite by removing the Biosecurity (Varroa Mite) Control Order, which instructed beekeepers to monitor their hives and treat them for Varroa destructor under specific regulations.
The approved detection strategies included sugar shaking, soapy water washing, alcohol washing and drone blood trapping — some of which are deadly to both varroa mites and honey bees.
The order also authorised officials to test NSW beekeepers' hives for the mite and exterminate the infected bees.
Chief Plant Protection officer Shane Hetherington argued there was no longer a need for regulation because there was no "significant risk to production or market failure to NSW beekeepers".
Dr Hetherington insisted training programs for beekeepers were an effective substitute to this regulation.
Victoria and Queensland now on the front line in varroa fight
Varroa mites have not yet been detected outside NSW.
Queensland and Victoria are leading the effort against the spread as they anticipate that honey bees will move between hives as the weather warms up in spring.
Feral hives and pollinators-for-hire both move into other areas for the spring pollination season — a necessary service for pollen-dependent crops which has so far complicated the mite's eradication.
In a statement released last month, Queensland's Minister for Rural Communities Mark Furner said authorities would keep a close eye on the varroa mite hitchhiking its way across the NSW border — but did not promise to stop the invasion.
Queensland's strategy mimics the NSW approach of focusing on beekeeper education, but also includes the establishment of 18 sentinel hives across the Gold Coast region, Stanthorpe, and Warwick.
A sentinel hive is a closely monitored colony ready to raise the alarm if varroa mite does invade.
These three areas near the NSW border were identified as high-risk because pollination events are anticipated in early spring.
Victorian beekeepers also expect to see varroa mite invade "within the next few months" due to this pollination event.
The Victorian government has established 12 sentinel hives across the Murray River.
Despite their efforts, Victorian Apiarist's Association president John van Weeghel warned that feral hives will be severely affected by the mite when it arrives.
"Feral bee hives provide a lot of pollination services for many farm enterprises and home gardens, so their loss to the mite is likely to have significant impact," he said.
Other states are also taking precautions under the national response.
South Australia says emergency provisions for acaricides — chemicals used to exterminate ticks and mites — and surveillance materials will be distributed to beekeepers across the state in the event of varroa detection.
In February, the NT's Acting Chief Plant officer Sally Heaton told NT Country Hour that the territory would lift restrictions on the chemicals for this emergency purpose.
While Tasmanian beekeeper Jenni McLeod told the ABC last year that she hoped the Bass Strait would act as a "moat" keeping the varroa mite away, the state's government has introduced a reporting system for keepers called BeeTas.
Western Australia has followed NSW and the national plan in focusing on beekeeper education.
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