Solomons' bee biosecurity warning

28 May 2009

Two of Australia’s honey bee experts are conducting research in the Solomon Islands, developing strategies to control an invasion of Asian honey bees.

This should help the Australian honey bee industry manage its biosecurity.

Measures to control and eradicate this bee are being developed for two very good reasons.

The first is that Asian honey bees are a major competitor with our honey bees, they have been observed to rob all the honey from managed honey bee colonies, eventually leading to the colonies’ deaths.

The Asian honey bee is also a vector for varroa mites.

It was thought Varroa destructor was the only varroa of concern to Australian beekeeping interests but recent research shows Varroa jacobsoni is now reproducing on honey bees in Papua New Guinea.

V. destructor is lethal to our (European) honey bees (Apis mellifera) and it now appears that V. jacobsoni is also now potentially lethal.

On Asian bees, their natural hosts, both varroa species reproduce on the drone pupae, whereas they breed on both worker and drone brood when they infest European bees.

V. jacobsoni is widespread in Asian honey bees (Apis cerana) in the Pacific and South East Asia and previously caused less concern to Australia than the perceived villain, V. destructor, which is established in New Zealand.

Now there is a general acceptance of the inevitability of varroa mites arriving in Australia in future.

“There is belief that the major biosecurity threat posed by Asian honey bees to Australia is the possibility that they may carry and introduce varroa mites,” said NSW DPI bee livestock officer, Nick Annand.

However, according to Mr Annand, while the introduction of mites could be extremely damaging, Asian honey bees also represent a major biosecurity threat to beekeeping in Australia.

“The damage it has caused to the apiary industry on infested islands in the Solomons has been major and in some situations wiped the industry out,” he said.

“A similar impact could well occur with the establishment of Asian honey bees in some areas in Australia, particularly in the hot humid tropical regions of North Queensland.

“The threat of Asian honey bees should not be taken lightly.”

Since 1995 there have been 11 incursions or potential incursions of them into Australia.

Seven colonies were located and destroyed at Cairns since 2007 and an eighth discovered in the region last July, where some surveillance continues.

On a recent trip to Papua New Guinea, CSIRO’s Denis Anderson found that a strain of varroa mite is now reproducing on European honey bees.

“The extent of the outbreak indicated that the mite is well established in the A. mellifera population, is widespread, and cannot be eradicated,” Dr Anderson said.

“This will have major implications regarding biosecurity issues for Australia.”

“This latest finding by Denis Anderson only amplifies the need for rigorous biosecurity for Asian honey bees across the north of Australia, particularly in the Torres Strait and on boats coming from PNG and neighbouring Indonesian Papua,” Mr Annand said.

Maintenance of Australian honey production and the contribution by honey bees to pollinating a large range of agricultural and horticultural crops has been valued at $3.8 billion per annum.

One of the aims of the Solomon Islands project is to help re-establish the more productive honey bee where it has been eliminated by Asian bees.

The invasion of the Asian bees into the Solomons since 2003 saw a major decline in the honey produced, as they out competed European bees for food (nectar and pollen).

Suppression of feral Asian bee populations is intended to increase competitiveness of European bees, in the hope that production from the latter will return to normal.

In the Solomons, the industry provides earnings for communities that rely heavily on subsistence agriculture and fishing for survival.

The Australian Centre for International Agricultural Research is funding the project.

Contact Nick Annand, Bathurst, (02) 6360 1210, nick.annand@dpi.nsw.gov.au

Nosema disease is well established

Nosema ceranae is a cause of nosemosis of honey bees.

Nosemosis is the most widespread of adult bee diseases and causes significant economic losses to beekeepers worldwide.

Nosemosis was originally thought to be caused by a single Nosema sp, Nosema apis, but in 1994, a similar microsporidian was described in Asian honey bees (Apis cerana) from China.

The parasite was called N. ceranae and was subsequently detected in European honey bees (Apis mellifera) in Taiwan.

One culprit likely to be a cause of devastating Colony Collapse Disorder (CCD) in bees, which threatens food security, is showing up strongly in the eastern States.

An industry funded project is determining the prevalence of the bee parasite Nosema ceranae and extent of honey production losses it causes.

NSW DPI microbiological diseases and diagnostics research team leader and bee researcher, Dr Michael Hornitzky, has also demonstrated that N. ceranae can contaminate honey, indicating that honey may be a source of spreading the disease to bees.

“However, N. ceranae does not cause disease in humans,” Dr Hornitzky said.

His survey of honey bee colonies in Australia, funded by the Rural Industries Research and Development Corporation and carried out at the Elizabeth Macarthur Agricultural Institute, showed Western Australia to be the only State in which N. ceranae has not been found.

Dr Hornitzky has now found high numbers of infected bees in Queensland, where N. ceranae appears to be replacing N. apis.

“It is also quite common in NSW and Victoria but not so common in South Australia and Tasmania,” Dr Hornitzky said.

In his current study, Dr Hornitzky is looking over a two year period at 20 hives per apiary in a number of apiaries in various parts of NSW, Victoria and Queensland.

“In one NSW location, all 20 hives in the test apiary are infected with N. ceranae,” he said.

“It appears N. ceranae is replacing N. apis which has been recognised in bees since the early 1900s.”

N. ceranae is likely to be one of multiple causes of CCD, responsible for the death of hundreds of thousands of honey bee colonies in the US in the past three years.

The loss of such a large number of honey bee colonies has had a significant impact on the pollination of seed and food crops and threatens food security.

The precise cause of CCD is unknown.

“Bees can have the infection and not show any signs, but it progresses when conditions are right – for example, nutritionally stressed bees,” Dr Hornitzky said.

“Then the bug starts to multiply, producing millions of Nosema spores per bee and causes the death of adult bees which can result in the death of the hive.

“Consequently it may become as bad here in a few years as it is in Europe now.”

He said by monitoring apiaries with high and low N. ceranae infection levels, their honey production and the management practices of beekeepers, we may identify potential control strategies to minimise the effects of this new pathogen.

Contact Michael Hornitzky, Camden, (02) 4640 6311, michael.hornitzky@dpi.nsw.gov.au

Planning workshop against varroa incursion

NSW DPI honey bee authority, Dr Doug Somerville, has been asked to provide technical advice to a national workshop planned to improve Australia’s response strategies and arrangements for a future incursion of the parasitic mite, Varroa destructor.

The Federal Government authorities Plant Health Australia (PHA), on behalf of Pollination Australia and Animal Health Australia (AHA), are planning to hold the workshop in Melbourne in June to brief staff from State and other Federal Government departments in both the plant and animal sectors.

Dr Somerville (pictured), NSW DPI’s technical specialist in honey bees, based  at Goulburn, will talk about the structure and function of the commercial beekeeping industry, including an overview of the life cycle and seasonal variations within a bee colony, and explain the impact varroa mites would have on Australia’s pollination-based industries and the beekeeping industry.

The workshop will also provide a forum for pollination industries to understand Emergency Animal Disease Response Agreement arrangements and the AUSVETPLAN disease strategy for a varroa mite incursion.

Discussion will consider whether this and other bee diseases might be included in the Emergency Plant Pest Response Deed because there are many synergies between the requirements of an eradication of varroa mites and a plant pest.

This will be one of the few occasions that plant and animal industry interests will be working simultaneously together for a common benefit.

A second workshop is proposed for early in the new financial year to look at other arrangements if eradication is not feasible.

AHA and the Department of Agriculture, Fisheries and Forestry are assisting PHA with the projects.

The Rural Industries Research and Development Corp-oration (RIRDC), Horticulture Australia Limited (HAL) and Pollination Australia are all partners in the project providing funding.

Contact Doug Somerville, Goulburn, (02) 4828 6600, doug.somerville@dpi.nsw.gov.au

Further reading

Honey bees

- Ron Aggs