Control of Asian honeybees in the Solomon Islands

This project addresses a decline in honey production and loss of European honeybee colonies (Apis mellifera) in the Solomon Islands since the arrival of the Asian honeybee (Apis cerana). Research is aimed at reversing these declines by developing methods that, when implemented, will suppress the Asian honeybee populations. This, in turn, will increase the foraging competitiveness of the European honeybees and restore hive numbers. Other project research will develop and implement surveillance systems for Asian honeybees on islands currently free of the bee and determine the pest and disease status of both Asian and European honeybees throughout the Solomon Islands.
Since their initial detection in the Solomon Islands in 2003, Asian honeybees have spread to approximately half of the large Islands. Sea shipping and commercial logging operations have facilitated this spread. In some cases swarms of bees have been able to fly between islands that are close together. The arrival of the bees on Guadalcanal has resulted in a decline of hived European honeybee colonies from approximately 2000 hives in 2000 to five in 2008. This decline appears to have been a result of the newly arrived bees out-competing the European honeybees for floral resources, as well as robbing. Extension activities carried out in this project over the past year have led to the introduction of surveillance for Asian honeybees on Malaita Island, one of the last large beekeeping islands still free of the bees.
Trials aimed at suppressing Asian honeybees are now being conducted on Savo Island, as it contains no European honeybees. Approval to conduct the trials was obtained from leaders of the local community. Initially, different lures are being tested for their ability to attract forager Asian honeybees to bait stations containing a sugar reward. Once a suitable lure is identified and optimised, an insecticide will be added to it that the foraging bees will carry back to their parent colonies. The effectiveness of the insecticide in suppressing the island population of Asian honeybees will then be gauged. During the past year, 4 different lures were tested for their ability to attract forager Asian honeybees. The most effective and cheapest lure tested was a flat open dish, that initially contained fresh honey and honeycomb collected from a feral Asian honeybee colony, but which was subsequently replaced with 60% sugar syrup. When offered during early morning (before 9.00am) this lure attracted no non-target insects. The addition of an Asian honeybee swarming pheromone to the lure did not improve its attractiveness. However, early results indicate that low concentrations of eicosanol (0.1mg or less) may improve the attractiveness of the lure, as may the addition of an A. cerana footprint pheromone and odors extracted from coconut flower.
As part of activities aimed at determining the health status of honeybees in the Solomon Islands, two viruses were isolated from samples of dead adult Asian honeybees. Isolates of varroa mites, collected from both A. cerana and A. mellifera brood throughout the Solomons, were also identified by DNA finger-printing as the Java strain of Varroa jacobsoni. Reproduction by these mites was only observed on drone brood of A. cerana.