Varroa mite: inside the response – Vinehealth Australia

August 22, 2022August 22, 2022

With Varroa mite estimated to result in losses of more than $70 million per year in Australia if established (1), you’ve no doubt heard about Australia’s efforts to control outbreaks of the exotic pest in New South Wales.

In this article we provide some background on what Varroa mite is, what it does and Australia’s current emergency response efforts to protect our predominant European honey bee population used for commercial bee keeping.

What is varroa mite and what impact does it have?

Varroa mites are external parasites of adult honey bees and honey bee brood (eggs, larvae and pupae). The size of a pinhead, they are considered the greatest threat to Australia’s honey and honey bee pollination plant industries – a major problem to commercial and hobby beekeepers. As parasites, the mites act by weakening and killing honey bee colonies. European honey bees infested with varroa are likely to die within 3 to 4 years if left untreated (2). Varroa mite can also transmit honey bee viruses.

There are 2 species of varroa mite of concern – Varroa destructor and Varroa jacobsoni.

Varroa destructor affects Asian honey bees and European honey bees. They have been found in much of Asia, Europe, the USA, South America and New Zealand (3).
Varroa jacobsoni has a wide distribution on Asian honey bee throughout Asia, with Asian honey bees being the natural host of Varroa jacobsoni. This species does not normally reproduce on European honey bees, however, they have recently been observed reproducing on European honey bees at some overseas locations, raising concerns that the same may happen in Australia (3).

Varroa mites can quickly spread over long distances when uninfected bees contact infected bees, and through movement of infected hive products, hives and contaminated beekeeping equipment.

Varroa mites affect honeybees in every major beekeeping area of the world, except Australia. They do not affect Australia’s native bee population.

According to The Weekend Australian Magazine on 6 August (4), varroa mite in New Zealand has cost farmers many hundreds of millions of dollars in lost agricultural production, and has wiped out half the country’s beekeepers, who couldn’t afford the time and cost of combating the mite. Predictions are that if varroa mite becomes endemic in Australia, it will cost commercial keepers tens of thousands of dollars each year to treat their hives and will devastate many smaller operators.

Current state of play in Australia

On 22 June 2022, Varroa destructor was detected in two of six sentinel hives at the Port of Newcastle, NSW as part of routine surveillance. In response, a statewide emergency order was issued to control the movement of bees across NSW. This order initially disallowed all bee hives to be moved across the state. Other states also put in place control orders. For South Australia’s movement restrictions on bees, bee colonies, hive components, apiary products and appliances and bee keeping plant, refer here.

The response plan for the eradication of Varroa mite in NSW follows a strategy agreed between the apiary industry, NSW Department of Primary Industries, neighbouring jurisdictions and the Commonwealth.

For the first 54 days of their response plan, NSW put a series of biosecurity zones in place in order to stop the spread of varroa mite, inside the state boundary, deemed a general biosecurity zone :

A 10km emergency zone around a detection, where eradication plans are being enacted to euthanise hives within this zone.
A 25km surveillance zone around the detection site, where officials were monitoring and inspecting managed and feral honeybees to limit the likelihood of incursion into this zone.
A 50km biosecurity notification zone around the detection site requiring beekeepers within that area to notify DPI NSW of the location of their hives.

Beekeepers with hives in the 10km eradication zone are not permitted to move hives or honeybees away from their current site, move apiary equipment outside the zone, euthanise hives, burn or otherwise dispose of equipment (unless directed by an authorised biosecurity officer), or tamper with bees and hives, except as permitted above.

The aim of the response within the eradication zones is to eradicate all hosts of Varroa and maintain a program of host eradication in each zone for three years to minimise the risk of reintroduction of Varroa or survival of Varroa on undetected hosts within the zones (5).

Approved registered commercial beekeepers within NSW in the area outside the above biosecurity zones are now able to move hives within this area of the state under permit. Movement conditions for these beekeepers include, but are not limited to needing to:

Alcohol wash hives prior to moving;
Complete an online training course; and
Complete a declaration to ensure no prior movement into the above three emergency zones.

As at 18 August 2022, NSW DPI reported that the total number of infected premises totalled 99. Two days earlier, 55 days in to the Varroa mite emergency response, the 50km biosecurity notification zone containing 3,700 registered beekeepers, was transitioned into the general biosecurity zone.

All the latest information relating to the NSW response to Varroa mite can be found here.

As per the agreed response plan with industry, NSW DPI has been euthanising hives and equipment within existing emergency zones and continues to undertake tracing activities. As at end July, 2,487 hives were reported to have been euthanised, with estimates that each hive is home to between 10,000 and 30,000 bees (6).

As a means of early detection of diseases and pests in honey bee colonies, including varroa mite, Australia has a suite of sentinel hives placed at ports which are regularly checked. This includes sentinel hives situated near the Port of Newcastle.

Previous varroa detections

In 2018, Varroa destructor was detected in cargo at the Port of Melbourne (7). This instigated a surveillance and monitoring program which resulted in elimination of the swarm.

In 2016, 2019 and 2020, Varroa jacobsoni was detected on exotic Asian honey bee in Townsville. All cases were eradicated. Proof of Freedom from V. jacobsoni was declared in 2021.

Inside the response

Viticultural Consultant Liz Riley recently spent an hour inside DPI NSW’s Varroa mite control centre in Orange. This response is running 24 hours a day, seven days a week, with rotating staff each week.

Liz mentioned to Vinehealth that her visit provided a fascinating and impressive insight into the sheer size and complexity of such a logistical response in terms of the resources, systems and tools needed, as well as the importance of very close government and industry communications and intel.

References