Trying to introduce a successful biological control agent to control an invasive plant in Portugal: the case studyof the Australian bud-galling wasp (Trichilogaster acaciaelongifoliae) and Sydney golden wattle (Acacia longifolia)


Abstract: Acacia longifolia is one of the worst invasive plants in Portugal. Mechanical andchemical control methods in use are very expensive and frequently unsuccessful, due to thepersistent, long-lived seedbank accumulated in the soil. The biocontrol agent Trichilogasteracaciaelongifoliae targets reduction of A. longifolia seeds and has been successfully used inSouth Africa. This agent presents a potentially good alternative option for the control of A.longifolia in Portugal. Specificity tests, using 40 non-target plant species, indicated that T.acaciaelongifoliae would be a safe biocontrol agent. Oviposition in non-choice tests wasdetected in three non-target species but subsequent trials involving potted plants and surveysin the field (in Australia and South Africa) showed that galls only developed on A. longifolia.These promising results encouraged an application for its release in the wild in Portugal, backin 2011, and the process has come a long way since then. The Portuguese Authoritiesinformed European Commission/Standing Committee on Plant Health about the proposal andthe decision was taken to send it to EFSA for pest risk assessment. The technical advice fromEFSA resulted in a permit to release this agent in July 2015.

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