An Introduction to the invasive alien species of Union concern presents a brief, non-technical overview of the 47 animals and 41 plants currently listed as invasive alien species (IAS) of Union concern. The summaries include dedicated descriptions of the main biological and ecological features, along with information on their origin, present distribution in the EU and pathways of introduction into the EU. The summaries also present how each species threaten European native biodiversity, and which management measures are currently available to mitigate their impacts.

Some of these species are well-known uninvited guests in European cities and rural areas, for example the racoon (Procyon lotor) and the grey squirrel (Sciurus carolinensis). Others, such as the Asian hornet (Vespa velutina nigrithorax) or common milkweed (Asclepias syriaca) are smaller and less recognisable by the public, but nevertheless act as altering agents in European ecosystems. The common trait shared by all 88 species is their ability to tamper with local biodiversity and environmental balance, triggering a wide range of negative ecological impacts. They do so by reproducing and dispersing rapidly, feeding on native species or out-competing them for habitat and resources. On occasion they can also carry parasites and diseases that are lethal to native wildlife or dangerous to human health.

The overview provided in the Introduction to the Regulation on Invasive Alien Species includes examples of invasive alien species present in Europe, their pathways of entry, and impacts in the region. It further outlines appropriate management actions, awareness-raising campaigns, and an overview over key resources such as those held on the European Alien Species Information Network.

‘If IAS establish in one EU Member State, they may easily spread across borders to neighbouring countries. It is therefore strategic to tackle the problem at an EU level, as a coordinated response will have more effect than individual actions at Member State level.’ (Introduction to the Regulation on Invasive Alien Species, 2023)

To address the threats posed by invasive alien species to European ecosystems, the European Union has implemented ‘Regulation 1143/2014 on Invasive Alien Species’ in EU Member States. With the IAS Regulation, an EU-wide framework has been established to prevent, minimise and mitigate the impacts of IAS on European ecosystems and biodiversity. The list of Invasive Alien Species of Union concern is at the core of the EU IAS Regulation. The first Union list entered into force in August 2016, and was last updated to include 88 species in 2022.

The IAS Regulation features key elements to be considered for the effective control of IAS, specifically prevention, early detection, rapid eradication, and management. It is highly recommended to prevent the introduction of IAS in the first place, as the sooner action is taken, the less costly it is to address impacts related to IAS. In situations where introductions are not prevented, it is still less costly to eradicate new invasions than to control established IAS populations.

IUCN and its partners work with the European Commission to provide technical and scientific support for the implementation of the Regulation. These two brochures are the result of this collaboration. You can read about the scientific evidence and risk assessments of the invasive alien species of Union concern on the Commission’s official IAS webpage.