Top 20 environmental weeds for classical biological control in Europe: a review of opportunities, regulations and other barriers to adoption

Abstract

Summary Classical biological control remains the only tool available for permanent ecological and economic management of invasive alien species that flourish through absence of their co‐evolved natural enemies. As such, this approach is recognized as a key tool for alien species management by the Convention on Biological Diversity (CBD), the European and Mediterranean Plant Protection Organization (EPPO) and the European Strategy on Invasive Alien Species (ESIAS). Successful classical biological control programmes abound around the world, despite disproportionate attention being given to occasional and predictable non‐target impacts. Despite more than 130 case histories in Europe against insect pests, no exotic classical biological control agent has been released in the EU against an alien invasive weed. This dearth has occurred in the face of increasing numbers of exotic invasive plants being imported and taking over National Parks, forests and amenity areas in this region, as well as a global increase in the use of classical biological control around the world. This paper reviews potential European weed targets for classical biological control from ecological and socioeconomic perspectives using the criteria of historical biological control success, taxonomic isolation from European native flora, likely availability of biological control agents, invasiveness outside Europe and value to primary industry and horticulture (potential for conflicts of interest). We also review why classical biological control of European exotic plants remains untested, considering problems of funding and public perception. Finally, we consider the regulatory framework that surrounds such biological control activities within constituent countries of the EU to suggest how this approach may be adopted in the future for managing invasive exotic weeds in Europe.

The biology of invasive alien plants in Canada. 9. Impatiens glandulifera Royle

“…In British Columbia, it is spreading rapidly through the greater Vancouver area (Graham 2003; Clements unpublished observations), which features many sensitive riparian habitats important for rearing salmon. When thick patches of I. glandulifera die off in the fall, the stalks quickly rot exposing large areas of river banks and making them increasingly susceptible to erosion from high winter flows (Roblin 1994;Graham 2003;Sheppard et al 2006). Even during the growing season, the plants offer little protection against soil erosion due to their extremely shallow root systems.…”

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

“…More non-native species are being regulated than ever before and the regulatory pathways for the licensing of exotic weed biological control agents have been made clear by recent projects that have culminated in the release of agents from multiple taxa within the EU. There is no shortage of target weeds and ten of the species highlighted in the reviews by Gassmann et al (2006) and Sheppard et al (2006) are included as species of European concern in the recent EU Regulation on Invasive Species and more are likely to be added at each revision of the list. In the section of the regulation covering the management of invasive species that are widely spread, there is a requirement for Member States to have in place effective management measures within 18 months of their inclusion on the list, and that these measures should be proportionate and prioritised based on a risk evaluation and their cost effectiveness.…”

“…This is surprising considering the extensive use of biological control agents (BCAs) in glasshouses (Minks et al 1998;Eilenberg et al 2000), for which Europe is a leading region and the use of at least 176 species of exotic arthropods that have not been confined in glasshouses but released, against pests of agriculture, across Europe (Gerber et al 2016). The reasons for this are manifold and have been discussed by Sheppard et al (2006) and Shaw et al (2011) but a prime issue appears to remain the general ignorance of the potential of classical biological control of weeds amongst policy makers, which is exacerbated by their risk aversion mind-set. The purpose of this account is to document selected examples of weed biological control to illustrate the long history of its inadvertent practice in Europe and then to highlight its recent (since 2010) intentional and successful implementation.…”

“…Biological control of weeds is a recognised and widely applied tool in several regions of the world (Clewley et al 2012;Suckling and Sforza 2014), but the European Union (EU) is a noticeable exception (Sheppard et al 2006). This is surprising considering the extensive use of biological control agents (BCAs) in glasshouses (Minks et al 1998;Eilenberg et al 2000), for which Europe is a leading region and the use of at least 176 species of exotic arthropods that have not been confined in glasshouses but released, against pests of agriculture, across Europe (Gerber et al 2016).…”

Impacts of Solidago Gigantea, Prunus Serotina, Heracleum Mantegazzianum and Fallopia Japonica Invasions on Ecosystems

“…(Child and Wade, 2000). F. japonica was introduced into Europe as an ornamental plant in the 1820s and spread exponentially throughout Europe during the 1900s on disturbed areas, roadsides, and river banks via accidental transport of rhizome fragments (Sheppard et al, 2005).…”