Miticide resistance in Varroa mites

What Victorian beekeepers need to know

The first case of Varroa mite (Varroa destructor), in Australia, being resistant to pyrethroid based treatments was found in January 2026. This affects the use of the only two approved pyrethroid miticide treatments available in Australia: flumethrin (sold as Bayvarol); and tau-fluvalinate (sold as Apistan). The chemical resistance was discovered in a small number of apiaries in northern NSW after treatments were not working properly to reduce mite numbers. The NSW Department of Primary Industries and Regional Development (DPIRD) has confirmed the chemical resistance in Varroa mites.

A month later, the Queensland Department of Primary Industries (DPI) also confirmed this same resistance, known as the L925I genetic mutation, in mites in south-east QLD. This case is linked to the earlier detection in NSW. After identifying these links, both states worked together to identify a second genetic mutation called L925M, which is present in both NSW and QLD.

Another type of resistance, called formamidine resistance or the Y215H genetic mutation, was also found in the northern NSW and south-east Queensland apiaries after treatment failures. This reduces the effectiveness of Apivar and Apitraz in mites with those genetics. In NSW, cases have now been confirmed in parts of the North Coast, Mid North Coast, Hunter and New England regions, and central NSW.

South Australia confirmed resistance to both pyrethroid and formamidine treatment resistant groups in hives in the Pooginook Detection Zone. This finding was also linked to NSW cases.

The affected chemical products are the only four permitted synthetic miticides of the eight approved products currently available to control Varroa mites. The four unaffected products are all organic acids.

Miticide resistant mites in Victoria

Agriculture Victoria has confirmed that some Varroa mites in Victoria are resistant to both pyrethroid and formamidine based treatments. This news came after reports that treatments were not working to control Varroa mite numbers as expected. Genetic testing identified the L925I mutation in these Varroa mites. This mutation significantly reduces how well pyrethroid treatments (Bayvarol and Apistan) work. Further testing confirmed the same mites are also resistant to formamidine based products (Apivar and Apitraz), as is the case with the resistant populations in other states. If this resistance spreads, beekeepers will lose some of their main tools for controlling Varroa mites. This could lead to more mites in hives and more bee colonies being lost. Resistance can spread through chemical misuse, the sale and movement of bees, and from nearby apiaries.

Beekeepers are asked to monitor their hives and report suspected resistance or anything unusual. Monitoring and reporting helps to protect the beekeeping industry. Agriculture Victoria, NSW DPIRD and QLD DPI are working together to better understand how far miticide resistance has spread. Additional detections are expected in all states as testing continues.

State and territory governments, along with the Australian Government, are also continuing to work with the beekeeping industry through the National Bee Biosecurity Program and the National Bee Pest Surveillance Program.

Miticide resistance

Miticide resistance happens when some Varroa mites naturally have small genetic differences that help them survive a chemical treatment that would normally kill them.

Examples of this are the L925I and L925M mutations that can make Varroa resistant to pyrethroid treatments, and the Y215H mutation that can make Varroa resistant to formamidine treatments.

If the same chemical is used repeatedly, for too long or in the wrong way, the mites that survive will reproduce. These mites will pass that resistance to their offspring. Over time, more mites in the population become resistant and the treatment becomes less effective – or may stop working completely.

What this means for beekeepers

Once Varroa mites develop resistance to a particular chemical treatment it may become less effective or no longer work at all.

If mites develop resistance to one or more chemical treatments, beekeepers lose important tools for controlling Varroa mite populations.

Fewer effective treatment options can make it harder and more expensive to manage Varroa mite in your apiary. It can lead to higher mite numbers in hives, more colony stress, and more colony losses.

Approved organic treatment options include Formic Pro, Aluen Cap, Api-Bioxal, and Apiguard.

Beekeepers should use Integrated Pest Management (IPM), which means managing mites by using cultural, mechanical, and chemical options to control mite numbers and the damage that they cause.

You can learn more about these options and other management strategies at Integrated Pest Management — National Varroa Mite Management Program

What is being done about miticide resistance

The NSW Government (DPIRD) is leading the response and working with Agriculture Victoria and QLD DPI to understand how resistance came about. A large tracing and testing program is underway to understand where resistant Varroa mites are located and how far miticide resistance  has spread.

Additional detections are expected as testing continues.

Resistant mites have been detected in:

• NSW in parts of the North Coast, Mid North Coast, Hunter and New England regions, and central NSW.
• Northeast Victoria
• Queensland in Southern Downs, Ipswich, Logan, Brisbane, Redland Bay, Moreton Bay, Sunshine Coast, Paroo, and Bundaberg
• South Australia in the Pooginook Detection Zone.

Genetic analysis  by researchers at the NSW Elizabeth Macarthur Agricultural Institute (EMAI) has provided important insights. The viruses carried by the resistant mites indicate that this population is a separate incursion of Varroa mite into Australia from the mites first detected in NSW in 2022.

These mites already had  genetic mutations which gave them chemical resistance. The pathway for the more recent incursion is not known. So far, testing by the NSW Elizabeth Macarthur Agricultural Institute has shown there are no exotic (new) viruses in affected hives, such as deformed wing virus (DWV).

The Consultative Committee on Emergency Plant Pests has agreed eradication of this resistant mite population is not technically feasible, because Varroa is so geographically widespread. As a result, eradication will not be attempted.

States, territories, and the Australian Government continue to work with industry around Varroa mite, through the National Bee Biosecurity Program and National Bee Pest Surveillance Program.

What beekeepers should do

Beekeepers can protect their hives by following the Australian Honey Bee Industry Biosecurity Code of Practice.

To slow the development and spread of chemical resistance, beekeepers should be correctly rotating miticides between chemical types, and using alternative mite control methods, not just chemicals. Keeping mite numbers below threshold levels will also help slow the spread.

You can learn more about monitoring mite numbers and treatment thresholds here.  To check Varroa infestation levels, use the alcohol wash or soapy water wash method to wash 300 bees and refer to table on monitoring for Varroa mite webpage on National Varroa mite management website for control guidelines.

Always check mite numbers before, during and after treatments to ensure that the chemical is needed, and that it is working, or whether further action is needed.

If resistance to miticide treatments has been found, these miticides can no longer be used. Continuing to use them will allow resistant mites to survive and increase, leading to colony loss.

To help with selection of appropriate chemicals, you can use the Varroa Management Tool.

Because fewer chemical treatments may work in the future, it is important to start using Integrated Pest Management (IPM) methods that do not rely solely on chemicals.

Where mite numbers are uncontrolled, there may be limited ability to save colonies. Early reporting of suspected resistance is critical, along with changing to a different chemical group of miticides if needed to control mite populations.

Report treatment failures

Don’t hesitate to report any suspected cases of treatment failure: contact the Exotic Plant Pest Hotline on 1800 084 881.

For more information

Beekeepers can access free resources on managing Varroa mites at National Varroa Mite Management Program

For Varroa management advice contact our Victorian Bee Biosecurity Officers on 136 186 or email honeybee.biosecurity@agriculture.vic.gov.au