With the varroa mite here to stay, bees and beekeeping have never been more important! Beekeepers in other countries have been dealing with varroa for many years, and have developed a wide range of treatment methods that make it possible to successfully manage the mites.
For beekeepers in NSW, it’s going to be important to make sure you’re familiar with your hives - look after your bees well and carry out best practices for spring management, understand how to monitor for mites and do so regularly, plus keep up to date with the official directives.
The 19th of September this year officially marked the day that Australia joined the rest of the world in counting the varroa mite as endemic, with the government’s National Management Group announcing their decision to shift from an eradication stance to one based on management.
Varroa destructor mites were first detected in sentinel beehives at Newcastle port in June 2022, and since then a program aimed at preventing the establishment and spread of the mites has been undertaken by the NSW DPI. Despite these efforts, varroa continued to spread throughout the state with the movements of commercially managed hives for agricultural pollination.
Our hearts go out to all of the beekeepers who’ve had their bees euthanised as part of the containment effort, and we’re glad that further destruction of colonies can now be halted. Although it’s unfortunate that the eradication program hasn’t been successful, it’s important to note that the rest of the world has already learned how to live with the mites and shown that it’s very achievable.
How will varroa becoming established in Australia affect beekeeping and pollination?
The health of both managed and wild pollinators has never been so crucial, and the role of Australian beekeepers is now more important than ever. Beekeepers in other countries have been dealing with varroa for many years, and we can benefit from their insights in combating the pest here.
Beekeepers will need to monitor for mites, and apply treatments when their numbers increase beyond a certain threshold. Untreated and wild colonies will be at risk of dying out due to the effects of the mites. This will have a big impact on agricultural pollination, and the demand for commercial pollination will grow as the pollination services provided by feral honeybees dwindles.
Honeybees will need all the help and support we can give them as we tackle this new threat. We rely so much on pollinators for our food, thatevery step we take to protect our managed and wild pollinators is valuable. As always, if we look after the bees, they’ll look after us.
What is varroa?
Varroa destructor is a pinhead-sized mite that parasitises honey bees and their brood. (It’s not known to affect any ‘native’ bee species, only Apis mellifera and Apis cerana.) The mites severely weaken bees, and also carry damaging viruses. Until now, Australia had been the only continent to remain free from varroa mites.
The mites live on adult bees’ abdomens and feed on tissue called the “fat body”. They reproduce inside brood cells, with the young mites parasitising the developing bees.
Adult varroa mite on a nurse bee
Varroa mites on a developing bee larva
Adult females are rusty red-brown and measure 1-1.8 mm (around 1/16 inch) in length. They are round and flat and can be seen with the naked eye, especially when against a light-coloured background.
Adult varroa mite closeup
Varroa mite numbers increase in a hive over time and the buildup can occur rapidly. The mites weaken the bees, spread diseases and hinder brood development. If management strategies are not applied then the colony has a high chance of dying out unless it has pre-existing genetic resistance.
Varroa mites spread within a hive by reproducing on the brood and attaching themselves to adult bees. They can spread to new colonies through robbing, drifting, swarming and absconding. Beekeepers can spread the mites when moving combs from one hive to another, or moving bees to a new apiary. They can travel on clothes, equipment or vehicles.
How do people currently manage varroa in other countries?
Beekeepers around the globe have been dealing with varroa mites for decades. Monitoring for mites and treating them is an essential part of good beekeeping practice, and there are a number of methods that can be used to combat them.
Monitoring beehives for varroa mites
Beekeepers in affected regions typically check their hives for varroa mites several times a year. There are several different methods that can be used to monitor colonies for varroa, and these can be incorporated into regular brood inspections. They include:
We recommend keeping abreast of official monitoring recommendations from your state's official agricultural body.
Prevention and treatment of varroa mites
Good husbandry and hygiene can reduce the spread of varroa. In areas where varroa is present, beekeepers usually need to work to control the number of mites in their colonies. At the time of writing, approved treatment methods for use in Australia are yet to be finalised. Approaches to treatment include:
Integrated Pest Management is an environmentally sensitive approach to managing pests that integrates knowledge of the pest with a combination of practices and control methods. The goal of IPM in the context of beekeeping is to avoid harm, reduce pesticide use and maintain the health of honeybees. With this method, beekeepers try to prevent mites primarily through cultural and mechanical controls.
Cultural controls are preventative techniques that reduce the ability of the pest to reproduce. They include: keeping bees with genetic resistance to mites, using foundation with small cell comb, and interrupting the mite’s reproduction through a brood break.
Mechanical controls are methods that involve physically removing mites from the hive. Mechanical controls include: sugar dusting to increase bees grooming, using a screened bottom board and adding drone comb to the hive. Mites prefer to reproduce in drone comb, which can be removed before the mites emerge.
While cultural and mechanical controls can be effective in suppressing mite reproduction and keeping numbers down, there are times when chemical treatments may be necessary. When using chemical controls, many beekeepers prefer to start with the least toxic options, and only move onto more toxic methods as a last resort.
What should Australian beekeepers do now?
For NSW beekeepers - we recommend continuing to follow spring management best practices, keep monitoring your hives regularly as per the mandates.