Weed biological control in the European Union: from serendipity to strategy

Abstract

Biological control of weeds is a globally recognised approach to the management of some of the most troublesome invasive plants in the world.

Estimating economic benefits of biological control of Ambrosia artemisiifolia by Ophraella communa in southeastern France

“…Classical biological control aims to reduce the IAPS' abundance below an economic or ecological threshold and/or slow down its spread by the introduction of one or a few specialist natural enemies from the weed's native range (Müller-Schärer & Schaffner 2008). Usually, the introduction of specialist biological control agents is based on a decision process by competent authorities after careful evaluation of pre-release studies assessing the likelihood of non-target effects and impact of the agent, but in times of increased biological invasions (Seebens et al 2017), more and more potential biological control agents are also accidentally introduced into regions where IAPS cause problems (Shaw et al 2018) There is growing evidence that classical biological control, if successful, can play a major role in the sustainable IAPS management (Seastedt 2014) and that it is highly costeffective compared to other methods (Page & Lacey 2006;De Lange & van Wilgen 2010;van Wilgen et al 2012). Most of this evidence comes from retrospective studies, or ex-post studies, that compared actual data on the costs of implementing the program, the impact of the IAPS as well as the reduction in impact due to classical biological control, and therefore tend to provide relatively accurate estimates of the cost-effectiveness of this approach (Culliney 2005).…”

“…As a consequence of globalization, biological invasions have greatly increased over the past decades, and there is no evidence for a slowing down of new introductions (Seebens et al 2017). In this process, an increase of accidentally introduced natural enemies of IAPS has been reported, including species that are used or considered for use as biological control agents elsewhere (Shaw et al 2018). In general, the handling and relocation of an accidentally introduced exotic organism, be it a biocontrol agent or not, requires permission from national competent authorities, but such organisms usually lack a rigorous risk analysis for the target region.…”

Constraints in weed biological control: contrasting responses by implementing nations

“…Our impression, however, is that a nadir has been reached and that the precedents of the highly successful programs in New Zealand and South Africa, and early signs of rejuvenation of the discipline in Australia, lead to optimism. This confidence is given considerable added weight by the recent, intentional implementation of weed biocontrol in England and Portugal (Shaw et al 2018)-an involvement which took a decade to gain approval from the European Union authorities, but it is undoubtedly a major step forward. It is also most encouraging that Argentina and Brazil, that have long been crucially-important source nations for weed biocontrol agents, have now become the first countries in South America to commit to the implementation of weed biological control in their homelands (e.g.…”

Can Niche Dynamics and Distribution Modeling Predict the Success of Invasive Species Management Using Biocontrol? Insights From Acacia longifolia in Portugal

“…Biological control (hereafter biocontrol) has a long history (over a century) as a safe and effective strategy for the control of invasive plant species (Clewley et al, 2012) in several regions of the world, such as South Africa, Australia, or United States. Yet, the biocontrol of invasive plants was only recently (less than a decade ago) initiated in Europe (Shaw et al, 2018). Classical biocontrol consists on the deliberate introduction of a natural enemy of the target invasive species into a new region invaded by the latter with the objective of mitigating its competitive advantage.…”