Biological invasions are one of the main causes of species extinction in the world (and in Belgium) after the loss of natural habitats. Organisms can be intentionally or unintentionally introduced by humans outside their natural range. These include viruses, bacteria, fungi, algae, mosses, ferns, flowering plants, invertebrates and vertebrates. Not all exotic species are harmful, but Invasive Alien Species (IAS) can cause significant damage to nature and the economy. Many invasive alien species also promote the emergence and spread of infectious diseases, posing a threat to humans and animals.

IAS have a negative impact on native species and can have a profoundly negative effect on ecosystem functioning. On the economic front, they can negatively affect crop yields and clog waterways, among other things. In terms of public and animal health, they can cause serious problems because they can transmit parasites and diseases or produce allergens and toxins. They often entail significant management costs to limit their development, mitigate their damage or restore ecosystems. According to the Summary for Decision-Makers of the Thematic Assessment of Invasive Alien Species and Their Control (IPBES, 2023), preventing the introduction of invasive alien species is the most cost-effective management option. Coordinated strategies and action plans at the national level are essential to successfully manage biological invasions as part of a context-specific integrated governance approach.

At EU level, the Invasive Alien Species Regulation comprises a set of measures to be taken across the EU. The core of the regulation is the "Union list" or list of invasive alien species of Union interest. This is a dynamic list that is regularly updated and reviewed at least every six years. Species on this list are subject to restrictions and Member States must :

- act on pathways of unintended release (i.e. prevention).

- take measures for early detection and rapid eradication of these species.

- manage species that are already widespread in their area.

A cooperation agreement was drawn up in 2019 between the Federal State, Communities and Regions on for the prevention and control of the introduction and spread of invasive alien species in Belgium. This agreement ensures a coordinated implementation of the EU regulation on invasive alien species and facilitates the crucial exchange of information between the parties involved. As a result, three new national bodies dealing with invasive alien species were established: the National Scientific Secretariat, the National Scientific Council and the National Committee.

The Belgian action plan on priority pathways for the unintentional introduction and spread of EU-listed invasive alien species in Belgium was adopted in 2022 and aims to combat the unintentional introduction and spread of invasive alien species. The plan, prepared by the National Scientific Secretariat on IAS in cooperation with the competent authorities, meets the requirements of Article 13(2) of the EU IAS Regulation. It contains three thematic action plans: (1) on the introduction and spread of IAS through keeping for private or public purposes, (2) on the introduction and spread of IAS through recreational and professional activities in freshwater environments, and (3) on the introduction and spread of IAS through transportation of habitat materials, culture substrate and machinery.

Additional efforts and financial and human resources will be needed to combat biological invasions in Belgium and to achieve the EU Biodiversity Strategy 2030 target of "managing established invasive alien species and reducing by 50% the number of red-listed species threatened by them" and the K-M GBF to "reduce by at least 50% the rate of introduction and establishment of other known or potential invasive alien species by 2030". To achieve this, the EU IAS regulation must be fully implemented and the EU list must be continuously updated with IAS of particular importance to the European Union. The Thematic Assessment of IAS and its Control, adopted at the 10th Plenary Session of IPBES (2023), is an important source of recommendations for improving strategies to address IAS challenges.

In recent years, a considerable amount of work and awareness-raising initiatives for different target groups have been undertaken in Belgium at different levels of government (e.g. workshop for policy-makers, training for inspectors, production of identification brochures and videos, national surveys and citizen awareness campaigns). 

The threat posed by IAS is directly addressed by operational objective 2.5, but also by operational objective 2.2, which deals with internal and external trade.