Les séminaires de l'ISYEB accueillent Christophe Diagne, Anne-Charlotte Vaissière et Juliette Baron du Laboratoire Écologie, Systématique, Évolution de l'Université Paris-Sud.

Biological invasions are responsible of tremendous impacts globally, including biodiversity loss, which are associated with huge financial losses and management expenditures. Struggle efficiently against this major component of global change necessarily needs to improve public and policy awareness about these substantial impacts on our socio-ecosystems. One option to reach this objective would be to go through a large-scale assessment of the costs linked to these impacts. Up to now, a reliable cost synthesis of invasions has never been done at a global scale. We will introduce INVACOST, the most up-to-date, comprehensive, harmonised and robust compilation and description of economic cost estimates associated with invasive alien species worldwide. We developed a systematic, standardised methodology to collect information from peer-reviewed articles and grey literature, while ensuring data validity and method repeatability for constructing this living database, which currently contains about 2300 cost estimates depicted by several descriptors (e.g. taxonomy, spatial range, temporal coverage, estimation methodology). During the first part of our presentation, we will (i) present the rationale for this study, (ii) describe the multi-step process leading up to the current database, and (iii) provide opportunities and prospects for using INVACOST as an essential tool for worldwide research, management objectives and data-based policymaking. The second part of this presentation will be devoted to show how using INVACOST has allowed to implement a specific study at the interface between economics and ecology. Focusing on invasive alien mammals worldwide, we found that the conservative sum of the annual economic costs (for the 1945-2018 period) is of the order of US$ 16 billion (2017 US Dollars) annually and appears to be due to damage in high-income countries. The cost estimates analysed concerned - both directly and indirectly (e.g. physical damage, control operations, loss of income) - several sectors in our socio-ecosystems. Alarmingly, these costs are likely to be grossly underestimated for a number of reasons that will be discussed. Furthermore, preliminary statistics based on data at hand has also shown a robust structuring effect of the type of cost (damage/loss vs management expenditures) and the taxonomic gender on the distribution of the cost data. Finally, this work provides avenues for further research on this topic, and more generally on the investigation of economic impacts associated to invasive alien species at relevant scales.