BIOCONTROL TO PROTECT APPLE AND PEAR FLOWERS AGAINST FIRE BLIGHT USING BUMBLEBEES

摘要

Current control of fire blight caused by Erwinia amylovora in apple and pear orchards relies on two strategies. The first strategy requires regular monitoring for symptoms and removing the infected parts by cutting them back into the healthy tissues.The second strategy involves preventive sprayings with plant defense enhancer (PDE) molecules like fosethyl aluminium (Aliette*) and laminarin (Vacciplant*) as well as heavy metals (Cu and Mn) to reduce the plant susceptibility for the inoculum. However,during bloom when flower stigma and hypanthium are sensitive to fire blight infections some of these PDE molecules cannot be applied due to phytotoxicity problems. Developing an alternative strategy using biocontrol organisms (BCOs) to protect apple andpear flowers against fire blight infections is the main goal of this research project. Our approach also includes the continuous distribution of BCOs throughout blooming via bumblebee [Bombus terrestris) flower visits (entomovectoring). Several specificobjectives, from the assessment of the risk of fire blight dispersal by the bumblebees, over the acquisition of BCOs by bumblebees and the attractiveness of the nectar to entice pollinators, to the potential of the tested BCOs for blight control were tackled.