Modern classical biological control (or importation biological control) of invasive non-native weeds aims to mitigate their negative impacts on biodiversity, ecosystem services and human well-being. It implies the deliberate release of specialist natural enemies from the weed’s native range to reduce the densities or the spread of a weed in its introduced range. Assessing the likelihood of non-target effects by a potential biological control agent is one of the fundamental challenges of pre-release studies in biological control projects. The long history of pre-release studies in biological weed control has significantly contributed to the development of environmental risk assessment procedures. Yet despite its wide application across the world, discussions about the risks involved in classical biological weed control are often dominated by misunderstandings and misconceptions. By addressing some of these misconceptions, I will elaborate key questions that should be raised in public and scientific debates on the potential risks and benefits of releasing exotic organisms to control exotic invasive weeds. Finally, I will propose a path forward to further increase efficacy and safety in future projects and conclude by advocating to do classical biological control of weeds more rigorously and more often.

Speaker: Urs Schaffner. Urs Schaffner is Head of the ‘Ecosystems Management’ section at the CABI Switzerland Centre and affiliate assistant professor at the University of Idaho, USA. His research focuses on soil-plant-herbivore interactions, with particular emphasis on biological invasions, biological control of weeds and grassland restoration. He has 25 years of experience in weed biological control and has worked on aspects such as the ecology and evolutionary ecology of host-specificity of weed biological control agents, pre-release impact assessment, demographic modelling of biological control agents and post-release impact evaluation. Currently he leads a multi-partner project on assessing the environmental and socio-economic effects of invasive trees in Eastern Africa and implementing integrated management strategies, including biological control, that mitigate their negative impacts.

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