This article is based upon work from the COST Action TD1209: Alien Challenge. COST (European Cooperation in Science and Technology) is a pan-European intergovernmental framework. The mission of COST is to enable scientific and technological developments leading to new concepts and products and thereby contribute to strengthening Europe’s research and innovation capacities. PGM was supported by the CABI Development Fund (with contributions from ACIAR (Australia) and Dfid (UK) and by Darwin plus, DPLUS074 ‘Improving biosecurity in the SAUKOTs through Pest Risk Assessments’. MV by Belmont Forum-Biodiversa project InvasiBES (PCI2018-092939). CP by Sciex-NMSch 12.108. JMJ and WCS by BiodivERsA (FFII project; DFG grant JE 288/7-1). JMJ by DFG project JE 288/9-1,9-2. CR and MB by Fundação para a Ciência e a Tecnologia grants SFRH/BPD/91357/2012 and SFRH/ BPD/86215/2012, respectively. PS by MESTD of Serbia, grant #173025. JP by RVO 67985939 and 17-19025S. JCC was supported by a starting grant in the framework of the 2014 FCT Investigator Programme (IF/01606/2014/CP1230/CT0001).