The importance of exotic mite surveillance in Australian beekeeping

Rod Bourke, NSW Bee Biosecurity Officer

Sugar shaking is easy on the bees (and the kids love it). Image courtesy of Rod Bourke

An important part of my role as a Bee Biosecurity Officer is preparing beekeepers to manage exotic mites such as varroa and tropilaelaps in case they establish in Australia. I do this by training and encouraging beekeepers to monitor their hives for these mites, even though they are not here!

Australia is extremely lucky to be free from these mites, but if they were to arrive, beekeepers may play a big role in their early detection and determining how far they have spread. This means that an effective containment and eradication program could be implemented sooner and have a better chance of being successful.

Some say it’s not a matter of if but when varroa gets here, so we need to be prepared. In recent years we have had two separate incursions of Varroa jacobsoni on Asian honey bees in Townsville (both contained), and a Melbourne interception of V. destructor on a European honey bee colony living in a crate of goods in a shipping container from the United States. This colony was destroyed, and subsequent Agriculture Victoria surveillance showed that no incursion had occurred.

While the pessimists may feel we have no chance of stopping varroa (or tropilaelaps), the various agencies involved with programs to protect our shores feel that is definitely not the case, especially if the beekeeping industry are proactive in looking for them.

Plant Health Australia recently hosted a 2-day online workshop – attended by the Bee Biosecurity Officers – which reviewed the National Bee Pest Surveillance Program and looked at how surveillance can be tightened.

While sea and airports are high-risk entry points for mites, they may also arrive in other ways and places, so everyone needs to be on the lookout for them.

Under the Australian Honey Bee Industry Biosecurity Code of Practice (the Code), all apiarists must undertake at least two exotic mite inspections on one hive (doesn’t need to be the same hive each time) within each apiary per season. Generally, this would be done at the same time as your spring and autumn brood checks (looking for mites on bees in the brood box).

Autumn is NSW DPI Sugar Shake Season, and a reminder for anyone who has not yet completed an autumn brood check and mite surveillance to get moving and do them. Depending on the weather in your region, schedule your autumn brood inspections before it gets too cold. This will ensure your hives are in the best condition to survive a long, cold winter.

When it comes to the type of mite surveillance that works best for you, consider the following:

  • Sugar shaking does not generally harm bees and is reasonably effective in removing most of the mites from bees. This is probably the best method for most recreational beekeepers.
  • Alcohol washing is a little bit more effective at removing mites and is considered the most accurate method in determining overall mite concentrations. But beware: it kills the bees in the process, so ensure the queen isn’t in with those bees.
  • Drone uncapping (preferably of pink-eyed drone pupae) is only effective when hives actually have drone brood (depending on your location this can be seasonal) and does kill those pupae. Drone pupae are often the preferred varroa breeding sites in a colony (especially in spring) and pigmented baby varroa and the adults are very easy to spot.

Uncapped drone brood with varroa. Image courtesy of Rod Bourke

Varroa generally prefer to reproduce within drone brood, as the foundress mite has more time (before the drone would hatch) and can therefore rear more female mites. Varroa numbers increase faster in drone brood than in worker cells, so it’s likely that in the early stages of a varroa incursion that they could be found there first. Even so, there are many areas where you will not have significant (or any) drone populations when you want to undertake surveillance, so you should not rely solely on this method.

While in New Zealand with Mark Page (NSW BBO-surveillance) in 2019, we performed all three methods of mite surveillance on a hive, and drone uncapping quickly exposed mites in all stages of development.

We did a sugar shake and retrieved one varroa mite from the sample. We then performed an alcohol wash on the same sample of bees (which killed them), and retrieved an additional mite. This indicated that there were only a few mites in the sample, and that the sugar shake method was able to detect them. The message is, the more people we have looking for varroa, the more likely we can find it early and be able to eradicate it.

NSW Department of Primary Industries (NSW DPI) has developed an accredited Bee Emergency Response Training (BERT) program, which trains beekeepers to undertake mite surveillance to the required standard in case an exotic bee pest emergency response occurred (in NSW or any other state). I attended the first training session at Tocal in December 2020, along with other DPI staff and industry members. NSW DPI is aiming to train around 50 selected NSW beekeepers for BERT during 2021, which should enable a more effective emergency response.

At the end of the day, the important thing for all beekeepers to remember is that they should be routinely undertaking exotic mite surveillance of their hives. If an exotic mite becomes established in Australia, all beekeepers will need to spend more time and money to manage their colonies and keep them viable. So, we should all work hard to try to protect our industry from this threat ever becoming established.