Do you know what miticide resistance is?

Miticide resistance happens when some Varroa mites carry genetic traits that make them less likely to be killed by a specific chemical treatment. Within any mite population, there is natural variation — a few individuals may, by chance, have genetic differences (e.g., in proteins or detoxification pathways) that let them survive a treatment that kills most others. If the same chemical is used repeatedly, those surviving mites are more likely to reproduce and pass on those traits. Over time, resistant mites can become a larger proportion of the population, making that chemical less effective or even ineffective.

This process is a well-understood evolutionary response to repeated chemical pressure. It’s one reason pest-control programs aim to limit how often the same product is used.

How this changes Varroa Management

Australian beekeepers should be careful in their Varroa mite management choices to be able to ensure we can control Varroa mites for as long as possible with all the miticide options that we have available to us. If mites in Australia develop resistance to one or more miticides, that means losing an important tool in controlling Varroa populations. Fewer effective treatment options can lead to higher mite levels in hives, increasing colony stress and mortality.

To avoid the risk of the development of miticide resistance, beekeepers are advised to:

• Use integrated pest management (IPM) — combining monitoring, cultural/mechanical controls, and chemical treatments only when needed.

• Apply chemical treatments only when thresholds are exceeded, rather than on a fixed schedule.

• Rotate between products with different modes of action, so mites are not repeatedly exposed to the same active ingredient.

• Follow label instructions and dosage, because misuse can accelerate resistance development.

These approaches help preserve the effectiveness of available treatments for as long as possible.