The Solomon Experience With Asian Honey Bees

Asian honey bees (Apis cerana)

Asian honey bees (Apis cerana)

The Australian Centre of International Agricultural Research (ACIAR) is currently funding a project (Project No.HORT/2004/030) to develop management strategies in the Solomon Islands to control the recently introduced pest Apis cerana (Asian honey bee).  The Solomon Islands are a volcanic-derived group of islands that stretch more than 1000km from Papua New Guinea (PNG) through the south-west pacific towards Vanuatu. The Asian honey bee was first identified on the Solomon Islands in 2003 and has since spread and caused major losses to the European honey bee industry. In 2004 an assessment of the situation was done by CSIRO which concluded that:

  • the Asian honey bee was established and could not be eradicated
  • the Asian honey bee had introduced the Varroa jacobsoni with it.
  • the Asian honey bee was causing major losses to the European honey bee colonies and their honey yields.

A meeting between relevant industry stakeholders was held and it was agreed the industry was worth trying to save. This led to the evolution of a project by Dr Denis Anderson of CSIRO with the objectives:

  • To suppress the Asian honey bee.
  • Develop a surveillance system for Asian honey bees.
  • Identify pests and diseases present in the European and Asian honey bee populations and
  • study the reproductive lifecycle of Varroa jacobsoni.

To assist in the project Denis Anderson has drawn on Dr Mike Lacey (Biochemist CSIRO) for his knowledge and experience in insect attractants, Solomon Islanders Rex Ramoiau, Senior Bees Officer; Salome Ete, Livestock Officer (Bees) (both from the Ministry of Agriculture and Livestock); Sale Dove, manager of the Honey Producers Cooperative; and myself. 

The Solomon Islanders are predominantly Melanesian heritage with some outer islands inhabited by Polynesians. The language spoken is predominantly Pidgin English but most know a little English. The main export industries are fishing, forestry, copra, palm oil and cocoa. The Solomons are still relatively undiscovered by tourists, apart from divers, with whom it is famous. Much of the country is extremely beautiful with crystal blue waters, coral reef with lush tropical growth down to the waters edge.

The Solomon Islands are very poor and for the majority of the population their lifestyles are vastly different to how we live in Australia. Outside of the main towns like Gizo, Auki and Honiara (the capital city) very few people own cars, most houses are constructed with sago palms leaves, most villages have no electricity, and water is often only available from a communal tap or near by creek. The people are very friendly and helpful with village life gently paced yet busy. A very nice contrast to the often hectic, material possession-conscious consumers that many western societies have become.

Locals kids keeping cool

Locals kids keeping cool

Most of the population are heavily dependant on subsistence agriculture. Beekeeping is done in a small scale with only a few beekeepers owning 50 plus hives but most with 25 or less. The bees are stationary and produce honey yields of around 25kg/hive/year. Most of the honey is very dark with a high moisture content (19-21%). The majority of honey is collected during the drier season from April to October. Boxes and frames are made by local timber millers, but the beekeepers sometimes have troubles getting other supplies that need to be imported, such as foundation. Hive tools, smokers, veils and extractors are expensive for the beekeepers. This type of equipment is often shared between many.

Typical village in Malaita, Solomon Islands

Typical village in Malaita, Solomon Islands

The hive boxes lids and bases do not last much longer than 5 years, due to the hot humid conditions and limited use of preservatives. Honey is purchased for between $12 and $20 Solomon dollars (6 to7 Solomon dollar = 1Aussie dollar). Honey is sold locally, is also exported and some is sold to Japanese fishing boats. The keeping of bees within villages provides the beekeepers an opportunity to make some income with relatively low startup costs, low labour input, a low environmental impact and with the bonus of improved crop yields through increased pollination. These factors make beekeeping a very suitable industry for the Solomon Islanders. The money earned from a few hives can greatly assist in basic things such as school fees or medicines.

Since its initial identification on Guadalcanal in 2003, the Asian honey bee has been identified on approximately half of the larger main Islands of the Solomon’s. The spread of the bees has most likely been the result of general sea cargo movements, logging operations with machinery movements between the islands and also swarming bees flying between islands that are close together. The incursion of Asian honey bees on Guadalcanal (the largest island) has resulted in decimation of the European honey bee industry on that island. The island used to have approximately 2000 hives back in 2000, now in 2008 it is estimated that less than 5 hives still remain alive.

This rapid decline appears to have been the result of the Asian honey bee out competing the European honey bee for resources. The Asian honey bee was also robbing directly from the European honey bee hives. The Asian bees would loiter around the European hive entrance and sneak past the guards and rob what ever resources from the hive the European honey bee had been able to collect in competition with the Asian bees. The dwindling resources of the European hives led to their demise by starvation.

The Asian bees have also become a problem to the community, establishing colonies in what ever they find suitable (often wall cavities – 9 colonies were found in the wall cavities of a single building on Savo Island) and being a general pest to people. This situation is made worse by the ability of the bee to rapidly reproduce through regularly swarming throughout the year.

Exposed; an A. cerana colony in a wall cavity.

Exposed; an A. cerana colony in a wall cavity.

The project is developing ways to control Asian bee populations in targeted areas to allow the reintroduction of European bees in an environment that they can prosper and be productive. The idea is to lure and train as many of the Asian bees to feeding stations as possible and then poison them via the feeding bait stations. A range of ideas and lures are being trialled to attract the Asian bees to the feeding stations. Once adequate numbers of bees are feeding at the station an insecticide is added and the bees carry it back to their colonies. The social nature of the hive means the insecticide laced food is stored or fed to other bees killing the colony.

All European bees need to be removed from the area prior to baiting to prevent poisoning them. Once the toxicity of the insecticide has broken down the European honey bees will then be returned to the Asian bee free location. The idea is to initially restock the treated areas with European colonies produced on islands free of the Asian honey bees. This involves training, providing resources and coordination of beekeepers on other islands free of Asian bees to produce adequate colonies to sell as the baiting control techniques are developed and implemented. Over time the Asian bees will return and their populations will build to levels that will again threaten the European bee production and survival. Follow up treatments will be required following the same procedure as above.

We are also looking at strategies that better equip the European bees to survive with the Asian bees. Such as hives with reduced entrances to allow better defence of the colony to prevent robber entry. However this reduces air movement. Honey in the Solomon Islands is usually 19% + moisture content, due to the high humidity levels. To try and counter the reduced entrance size and increase air flow through the hive, increased ventilation (bee proof) is being trialled to assist in honey ripening and temperature regulation.

A well cared for larger sized apiary on Malaita. Malaita is still free of A. cerana

A well cared for larger sized apiary on Malaita. Malaita is still free of A. cerana

Hive with reduced entrance size and increased bee proof ventilation.

Hive with reduced entrance size and increased bee proof ventilation.

V. jacobsoni as found in the Solomons is not a major issue to the European honey bees as it cannot reproduce on that bees’ brood  - it can only reproduce on the drone brood of the Asian bee. However adult female V. jacobsoni do invade European bee colonies and enter the brood cells but with little to no impact to the bee or the colony.

Two Adult female Varroa jacobsoni unable to breed on Apis mellifera drone pupae

Two Adult female Varroa jacobsoni unable to breed on Apis mellifera drone pupae

This project work could provide very helpful assistance to the Solomon Islands through the development of management approaches that would enable the continuation and re-establishment of an apiary industry through those areas that have been affected by Asian bees. It provides a way to earn some money for those communities that rely heavily on subsistence agriculture and fishing for survival.

Some of the strategies developed to control Asian honey bees in the Solomon Islands may also assist our local industry with biosecurity. Since 1995 there have been 11 incursions or potential incursions of A. cerana into Australia. The last being in 2007 at Cairns where 7 colonies were located and destroyed and some surveillance still continues (indeed, an eighth colony was discovered in the Cairns region on 29 July 2008). Prior to this incursion no other involved more than 1 colony. Techniques developed in the Solomon Islands may well assist when Asian honey bee incursions occur into Australia.

There is belief that the major biosecurity threat posed by A. cerana to Australia is the possibility that it may carry and introduce a mite into the country and the bee itself is only of nuisance value. Yes, the introduction of certain mites could be extremely damaging to the apiary industry, but please also consider the bee itself as a major biosecurity threat to beekeeping in Australia. The damage it has caused to the apiary industry on infested islands in the Solomon’s has been major and in some situations wiped the industry out. 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. They are a major pest in the Solomon Islands to beekeepers and the community and could cause similarly problems here in Australia. Which areas of Australia will be impacted, lets hope we never find out.

Denis Anderson on a recent trip to PNG found that a varroa mite is now reproducing on A. mellifera.  The extent of the outbreak indicated that the mite is well established in the A. mellifera population, is wide spread, and cannot be eradicated.  This will have major implications regarding biosecurity issues for Australia.  Investigations into the identity of this mite are in progress as I write.  An important question with no answer to date, is whether this mite can breed and be vectored by the local Asian honeybees. This latest finding by Denis Anderson only amplifies the need for very 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.

Author: Nick Annand, NSW DPI Bathurst