Up until 2022, Australia was free from varroa destructor, a pernicious ectoparasite of apis mellifera, the western honeybee.
Ever since then Australia has faced the very real threat that varroa poses to honeybees across the rest of the world.
Regardless of what we think of the situation, one thing is clear. Every beekeeper now needs to learn how to manage their beekeeping operation with the presence of varroa mite. This is a substantial change from pre-varroa beekeeping.
About varroa
As a parasite, varroa feeds on larval and adult bees. As it feeds, it weakens the bees and impacts their immune system, larval development, and overall capacity to "bee" ie social interaction, foraging and navigation capability, and endurance and longevity. Varroa mites are a key vector for the spread and evolution of honeybee viruses. In addition to the other effects of varroa mite parasitism, these viruses can quickly lead to unhealthy hives that collapse and die.
Varroa mites require capped brood in which to reproduce successfully. As hives expand in spring (more brood), the numbers of varroa mite also increase. In addition to that natural growth, hives may face high levels of mite immigration as forager bees carry varroa back to the hive. They may have encountered a bee with a hitchhiking varroa mite, or they may have found a weak/dead hive that is laden with varroa mite looking for a new home.
Mite immigration will be a significant challenge as the initial wave of varroa spreads through the country. This can lead to significant "re-infestation" events as unmanaged hives see enormous mite populations before collapsing.
Varroa mite is now endemic in New South Wales, and has been detected in several sites in Victoria (as of December 2024), while other states remain free from this pest. Free, but for how long?
It is inevitable that varroa mite will spread across the country, regardless of how vast our sunburnt land is. The east coast, being highly connected corridor of urban, rural, and bushland settings, will see the fastest spread. This will be partly natural spread through wild (feral) honeybee colonies, and human-assisted spread via migratory beekeepers or ignorant beekeepers unaware of the varroa threat. Worse, the spread may be deliberately done by bad actors intent on causing mayhem and damage.
What can beekeepers do
As a beekeeper, it is imperative to learn how to manage this pest BEFORE it arrives. Once varroa arrives in your hives it's probably too late.
Beekeepers are encouraged to learn how to apply Integrated Pest Management (IPM) as an approach to control and mitigate the impacts of varroa mite on their colonies. IPM is a management approach used in many industries and can readily be applied to varroa mite management in honeybees. The main focus of IPM is integrating monitoring, planning, and a wide variety of control mechanisms to maximise the benefits across the managed livestock or crop. IPM fundamentally depends upon understanding the levels of infestation, the lifecycle, and weaknesses of the pest to enable the beekeeper to make informed decisions and build appropriate management plans.
It all starts with monitoring.
Regular monitoring allows you to understand pest levels, impact, and predict when the pest may get out of hand and need some control action. Monitoring also allows you to measure the effectiveness of your control strategy and to adapt and adjust your management in a timely fashion. Without monitoring data, the beekeeper would simply be guessing, and taking actions without any data to guide those decisions.
Understand IPM and available control options.
Integrated Pest Management encourages you to use many different approaches to control and manage a pest in your livestock. Understanding IPM specific to your pest (in this case varroa) is important. IPM planning and decisions depend on this understanding of your pest, your livestock, your operation, and your environment.
Control options include cultural, mechanical, and chemical treatments. Starting at the base of the IPM pyramid and moving up, the control options may be more effective and require less manual effort, but they may have residual effects and be more expensive. The aim is to use the lower levels of IPM controls in preference to the higher levels (ie synthetic chemicals). Cultural and mechanical control mechanisms may be cheaper and simpler, but may have lower effectiveness and may require more beekeeper effort/labour. However, these mechanisms are chemical-free options to help keep varroa levels down and reduce long-term costs associated with chemical treatments.
Build a plan
Even if your first version of a plan is wrong, it helps to have something written down. You can always adjust and adapt as you learn.
Understanding what your bees are doing throughout the season is essential. This will help you understand how the mite population may be growing.
Based on that understanding, you can use IPM to map in decision criteria, controls, and other activities that may be applicable at different times through the season for your beekeeping operation. You can also build contingency plans to activate when unexpected things happen.
Plans are not meant to be perfect or written in stone. The best plan is the one you have. A better plan evolves as you learn! You may have many iterations of planning, and as your operation changes, your plan needs to adapt to those changes.
Last step is treatment when necessary.
Eventually, it is almost certain that varroa levels will be so high that a chemical treatment is required to keep the colony alive and well. Without some kind of treatment honeybees in Australia will almost certainly fail under the pressure of varroa mite - ie Parasitic Mite Syndrome (PMS). In that situation the failing hive has extreme numbers of mites that can readily spread to nearby hives, thus magnifying the problem and causing more colonies to suffer. Beyond the impact of varroa mite on the colony, there are areas in Australia where Small Hive Beetle is a significant pest, especially of weak colonies that cannot defend the hive. If varroa doesn't kill the colony, SHB will finish the job for sure. In other areas, winters can be fairly harsh, and sick bees affected by varroa will struggle to survive through winter.
Use only permitted treatments
AHBIC lists a table of currently permitted (or permit in process) chemical treatments. Some are organic, and some are synthetic treatments. Each treatment has specific conditions of use and modes of action. It is imperative that beekeepers read and understand the permit (issued by APVMA), application of chemical, and keep all relevant records of treatments.
As honeybees produce honey, it is vital that only approved treatments are used. This ensures the honey and other products harvested from your hives are safe for human consumption. Experimental treatments and unapproved chemicals could lead to serious consequences for the consumer's health and the beekeeper's liability and reputation. It could also seriously affect the beekeeping industry.
Varroa mite is adept at developing resistance to synthetic chemicals, as has been seen in many other countries. As they become resistant to specific treatments, the effectiveness of that treatment quickly drops and becomes useless as a treatment option. It is essential that beekeepers rotate treatments on their hives to minimise the risk of resistance developing in the varroa population.
Light at the end of the tunnel.
There is hope, however! Queen bee breeders around the world have shown that apis mellifera can develop traits that improve it's resistance to varroa destructor. These traits can be selectively bred, and after several generations, they can be highly effective at reducing the colony-level impact of varroa and also the viruses they spread.
In quite a few countries resistant populations of honeybees have been growing and are enabling beekeepers to remain treatment-free year-round. The UK, USA, Cuba, South Africa and other countries all have populations of varroa-resistant honeybees. This demonstrates that with some focused effort here in Australia, we too will be able to produce varroa resistant honeybee stock. However, this breeding process takes time, between 5 and 10 years, and requires knowledgable queen bee breeders to take the lead.
In the meantime, we all need to become better beekeepers and manage the varroa levels in our colonies.
Who are you going to call?
Each state across Australia has implemented a wide variety of assistance for beekeepers. The first line of practical help are the Varroa Development Officers in your jurisdiction. These folks are beekeepers themselves and have a broad understanding of Varroa IPM. Quite a few have practical hands-on experience managing varroa in other countries and have a wealth of knowledge to share with beekeepers. The aim of the VDOs is to build capability BEFORE varroa arrives, to help beekeepers be prepared early for the challenges ahead, and to assist and advise as varroa mite spreads throughout the regions.
VDOs can be contacted for assistance, and can visit in person to help beekeepers face to face in their apiary. All beekeepers are welcome to call on their state VDOs, and the service is provided free of charge under the NVMMP funding arrangements.
Other resources
NVMMP training can be found here
NVMMP Varroa Basics course can be found here
QLD varroa map: here
NSW varroa map: here
AHBIC provides a handy chemical treatment reference table: here
Plant Health Australia provides free BioSecurity Online Training (BOLT) and this provides a certificate of completion. Link here
In each state NVMMP Varroa Development Officers are available, and you can find details under the NVMMP Get Help section by state or by contacting the NVMMP. VDOs provide free consultation and training for all beekeepers.
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