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.