On the 27 June 2016, Asian honey bees (Apis cerana) were found infested with Varroa jacobsoni at the Port of Townsville, Queensland. These bees were found in an unused shipping container stand and are believed to have been there for up to two years before they were noticed.

A second detection of Asian honeybees occurred on 17 July 2016 where they were found in a bird-nesting box. After closer examination it was revealed that Varroa jacobsoni was also present in this nest.

Overall, a total of ten detections of Asian honeybees have occurred within the Townsville area. Of these, only two have had Varroa and overall a total of six individual Varroa jacobsoni mites have been seen.

This incursion has triggered a major response led by Biosecurity Queensland that aims to both contain and eradicate the threat. In order for these activities to happen, APAL, along with other affected industries as well as the government, is entering a cost-sharing agreement as per the Emergency Plant Pest Response Deed (EPPRD).

Varroa jacobsoni – a major threat

Varroa mites are a major parasite of honeybees and they occur in all honey bee production areas worldwide except Australia. The main effects of Varroa in Australia would be that it could lead to the collapse of nearly all wild European honeybee (Apis mellifera) hives, which will result in even more reliance on paid pollination services. The costs of management and upkeep of hives will likely increase and many hobby beekeepers will unlikely be able to cope with these extra requirements.

If Varroa did take hold, Australia would probably see most industries scale up their hive densities causing increased demand and prices for hives for pollination services. Reduced pollination stemming from a combined lack of wild honeybees and pollination services could result in yield and quality losses for many pollination-reliant crops.

Importantly, at the moment, the mite detected in Australia is Varroa jacobsoni – this species only uses Asian honey bee as a host. APAL says that if the industry ignores this threat, there is a risk that Varroa jacobsoni could jump hosts and become a parasite of European honeybee. This has happened in Papua New Guinea, although it did take thirty years.

The most common mite worldwide is Varroa destructor, which is responsible for most of the destruction of European honeybees. Varroa jacobsoni mainly affects Asian honeybee, which is much better adapted to both types of Varroa, compared with European honeybees. With Asian honeybees, the effect of Varroa is restricted to the drone brood whereas with European honeybees Varroa will affect both workers and drones.

Responding and paying for Varroa’s erradication

APAL became a signatory of the Emergency Plant Pest Response (EPPR) Deed on 24 October 2004, which essentially formalises government (Commonwealth and State) and plant industries’ roles in responding to exotic plant pests. In a levy meeting held in August 2007, Australian apple and pear growers agreed to establish the EPPR levy in order to respond to exotic pest incursions. At the time the levy was set to zero – so growers pay nothing – and so far it has been unnecessary to collect any funds.

But with the new Varroa threat, the levy now has to be activated and growers will have to contribute funding to help with the eradication programme.

For the levy to be activated, APAL says it must follow a consultation process that involves a notification to the industry in a manner which it reasonably expect will reach and be accessible to levy payers. This notification period is followed by a minimum objection period of thirty days. Levy payers can raise concerns to APAL and the Department of Agriculture and Water Resource by contacting them at [email protected].

APAL is one of the largest industry contributors to the response due to its local value of production (LVP) and high reliance on pollination. The amount APAL has agreed to contribute is $411,580 over four years. We estimate this will cost an average 20-hectare apple and/or pear growing business around $150 each year over the four-year period.

The levy will also fund APAL’s contribution to the Torres Strait Fruit Fly eradication programme, which is approximately $28,000 per year or an additional and ongoin cost of $41 per 20 hectare apple and/or pear growing business.  Currently APAL pays for the Torres Strait Fruit Fly programme using APAL funds and part of the Plant Health Australia levy.

Pollination is critical for apples and pears

One part of working out how much APAL contributes to a response plan is to determine our reliance on pollination. There is limited Australian-based research on pollination for apples and pears, however, it is widely accepted that European honeybees are crucial in pollinating our crops each year. The main research was done in the 1970s by Langridge and Jenkins, who used cages to exclude bees at flowering. Excluding bees at flowering gave significant reductions in fruit set, yield, and seed numbers.

Effect of caging apple (Yates) trees on fruit set, yield and seeds

Source: Langridge and Jenkins, 1970.

Effect of caging pear (Winter nellis) trees on fruit set, yield and seed number

* Reduction was significant
Source: Langridge and Jenkins, 1970.

Importantly, these studies done in Australia confirm that European honeybees increased yield 13.5 times for apples and 6.6 times for pears. Quality was also improved as indicated by the number of seeds per fruit.

The number of seeds per fruit refers to a relationship between misshapen unmarketable fruit with the number of fertilised ovules, well-formed seeds. Quality is improved because more fertilised ovules and well-formed seeds per fruit will decrease the number of misshapen and lopsided fruit.

Asian honeybees also a threat

Asian honeybees in their own right are seen as a threat to the honeybee and pollination industries and have already established themselves in Cairns (Far North Queensland) since 2007. The Asian honeybee prefers tropical climates and until now, they have not been seen in the southern part of the country in apple and pear growing regions.

Asian honeybees are highly competitive against European honeybees in foraging, inter-species mating and are natural hosts of both Varroa destructor and Varroa jacobsoni, which means they are likely to assist Varroa’s spread. They tend to nest in small cavities in buildings or tree hollows and fly very quickly and erratically, robbing honey stocks and reducing fertility of hives and ultimately causing collapse of colonies headed by European honeybee queens.

It is unlikely that Asian honeybees can be managed for honey production or pollination services like European honeybees, due to their frequent swarming and tendency to abscond.

Cost-benefit analysis of Varroa eradication in Australia

In Australia, the average cost per hive is $80 and hives are used, on average, at the rate of one hive per hectare although two to three hives are recommended.

If Varroa were to become established in Australia, the increase in both hive density and cost per hive would mean that the costs of pollination for an average 20-hectare apple and/or pear orchard business would increase to between $4,500 and $14,000 per year.

Source: APAL