Dispersal of the biocontrol agent Aureobasidium pullans for fire blight control using honey-bees (Apis mellifera carnica)

摘要

The effectiveness of using honey-bees to disperse mixture of two strains of Aureobasidium pullulansCF10 and CF40, active ingredients of Blossom Protect from hive-mounted dispenser to apple trees incontrolled greenhouse experiments as well as to apple and pear trees in two orchards in Vorarlberg andUpper Austria was evaluated during spring 2005. In addition, in greenhouse trials on plant-to-planttransport of Erwinia amylovora and the potential of dispersed A. pullulans strains to reduce fire blightincidence was studied. Samples of freshly stored nectar and honey were collected from hives in twoorchards and were tested for the presence of distributed strains. In greenhouse experiments, beehiveswith approx. 1500 bees and in orchard experiments commercial honey bee colonies were used. All hiveswere equipped with dispensers. Populations of A. pullulans-like colonies on flowers collected fromhoney-bee-delivered treatment in greenhouse trials were higher than those on flowers collected fromcontrol treatment. E. amylovora was detected on the majority of control flowers, which indicated a hightransfer rate from inoculated to control trees by honey-bees. Dispersed antagonistic strains showedsignificant potential to reduce the incidence of fire blight. After dispersal of A. pullulans CF10 and CF40in orchard trials from both locations, none of these strains could be re-isolated. Only a few viableantagonists were re-isolated from freshly stored nectar and honey. Our data demonstrate that thedispersal of the antagonistic fungi A. pullulans CF10 and CF40 using honey-bees in greenhouseexperiments represents a promising alternative to control fire blight. For an effective use of honey-beesin dispersal of antagonistic microorganisms in orchards, some improvements have to be made ondispenser construction and formulation of antagonistic material. Specific primers for the rapididentification of A. pullulans CF10 and CF40 should be developed.