EPPO Global Database

EPPO Reporting Service no. 03 - 2013 Num. article: 2013/074

Top 20 environmental weeds for classical biological control in Europe


Classical biological control remains the only tool available for permanent ecological and economical management of invasive alien species that are able to become invasive because their co-evolved natural enemies are absent. Many successful classical biological control programmes abound around the world, despite disproportionate attention being given to occasional and predictable non-target impacts. More than 130 case studies are known in Europe against insect pests, no exotic classical biological control agent has been released in the EU against an alien invasive plant.
Widespread alien plants invading non-cropping ecosystems in Europe was reviewed for their potential as targets for classical biological control from an ecological, social and economic perspective. The available scientific literature listing and prioritizing alien plants was cross-referenced. An aggregated list of over 200 species considered to be the most invasive alien plants in temperate and Mediterranean climates in Europe was then assessed against the following criteria:
  • Historical success of biological control against target invasive alien plant, ecological homologues and related species;
  • Taxonomic isolation of the species from European native flora (as a measure of risk of non-target damage);
  • Likelihood of suitable natural enemies being available as potential agents;
  • Target species value to agriculture, horticulture and forestry (potential conflicts of interest);
  • History of invasion outside of Europe (opportunities for international collaboration).
Following this assessment, 20 alien plants were prioritized as potential biological control target species for Europe, categorized into 3 groups of decreasing priority (species have a similar priority within each group). These species are listed below, with their area of origin, their climatic conditions and some of the criteria used to hierarchize them:

Group
Species
Area of origin
EU Climatic distribution
Genus native to Europe
Conflict of interest
Existing biocontrol programs

1
Buddleia davidii (Scrophulariaceae, EPPO List of Invasive alien plants)
As.
Temperate
No
Ornamen-tal plant
Yes
Fallopia japonica (Polygonaceae, EPPO List of IAP)
As.
Temperate
Yes
No
Yes








2
Acacia dealbata (Fabaceae, EPPO List of IAP)
Austr.
Medit.
No
Ornamen-tal plant
Yes, at least partial success
Azolla filiculoides (Salviniaceae, EPPO Observation list of IAP)
N-Am.
Temperate/
Medit.
No
No
Yes, at least partial success
Ailanthus altissma (Simaroubaceae), EPPO List of IAP)
As.
Temperate/
Medit.
No
No
Yes
Impatiens glandulifera (Balsaminaceae, EPPO List of IAP)
India
Temperate
Yes
Ornamen-tal plant
No
Rhododendron ponticum (Ericaceae, EPPO Observation list of IAP)
S-Eur.
Temperate/
Medit.
Yes
Ornamen-tal plant
Yes
Robinia pseudoacacia (Fabaceae)
N-Am.
Temperate
No
Forestry plant
No
Senecio inaequidens (Asteraceae, EPPO List of IAP)
S-Af.
Temperate/
Medit.
Yes
No
Yes













3
Ambrosia artemisiifolia (Asteraceae, EPPO List of IAP)
N-Am.
Temperate/
Medit.
Yes
No
Yes, at least partial success
Carpobrotus edulis (Aizoaceae, EPPO List of IAP)
S-Af.
Temperate/
Medit.
No
No
No
Heracleum mantegazzianum (Apiaceae, EPPO List of IAP)
Caucas
Temperate
Yes
No
Yes
Solanum elaeagnifolium (Solanaceae, EPPO A2 List)
Am.
Temperate/
Medit.
Yes
No
Yes, at least partial success
Baccharis halimifolia (Asteraceae, EPPO List of IAP)
N-Am.
Medit.
No
No
Yes, at least partial success
Hydrocotyle ranunculoides (Apiaceae, EPPO A2 List)
N-Am.
Temperate/
Medit.
Yes
No
Yes
Ludwigia grandiflora (Onagraceae, EPPO A2 List)
S-Am.
Temperate/
Medit.
Yes
No
Yes
Crassula helmsii (Crassulaceae, EPPO A2 List)
Australasia
Temperate
Yes
No
No
Elodea canadensis (Hydrocharitaceae)
N-Am.
Temperate
No
No
No
Myriophyllum aquaticum (Haloragaceae)
S-Am.
Temperate/
Medit.
Yes
No
Yes
Solidago canadensis (Asteraceae)
N-Am.
Temperate
Yes
No
No

Furthermore, the authors identify three constraints likely to be an obstacle adoption of classical biological control of invasive alien plants in Europe: (i) public perception, (ii) funding reliability and (iii) legislative and regulatory issues.


Sources

Sheppard AW, Shaw RH ; Sforza R (2006) Top 20 environmental weeds for classical biological control in Europe: a review of opportunities, regulations and other barriers to adoption. Weed Research 46, 93–117.