This special issue will comprise a selection of scholarly papers deriving from the research carried out within the Horizon 2020 project HOMED "Holistic management of emerging forest pests and diseases" (https://homed-project.eu). The articles concern various aspects of the ecology and management of invasive forest insect and fungal pathogen species in Europe. The special issue includes (but is not limited to) the following topics:

1. Stakeholder awareness of alien forest pests and diseases
2. Mechanistic models for predicting the risk of establishment and spread of invasive forest species at the continental scale
3. The relevance of the sentinel planting approach to identify potentially invasive species in forests
4. Coupling DNA-based in situ detection methods and next-generation sequencing pipeline to trace the origin of forest invading pests and pathogens
5. Deployment of multilure traps in port areas for early detection of alien forest insect arrivals
6. Use of the aerobiological monitoring network (allergenic pollen traps) to detect pathogenic fungal spores and monitor disease spread on a continental scale
7. Detection by drone of infestations by emerging or alien species at the tree level
8. Analysis of satellite data by artificial intelligence to delimit invaded areas
9. Associational resistance of mixed species forest to alien insect pests

In the last decades, a large number of non-native species (NNS) has been identified in several invaded areas worldwide. However, in both the European Union and other developed countries, despite existing measures for prevention and control, extant NNS are still expanding their distributional range and new NNS are being recorded. Whereas in developing countries, legislation for the successful management and control of (invasive) NNS is increasingly needed. Further, the invasiveness potential of NNS in several taxonomic groups remains unknown due to the lack of supporting risk screening studies, which are of crucial importance especially in those geographical areas acting as biodiversity hotspots. For the above reasons, there is room for improvement in risk screening studies to fill out these knowledge gaps.

Risk analysis studies provide crucial information for environmental managers and policy makers to prioritise decisions in view of appropriate management and conservation measures for both aquatic and terrestrial biodiversity. Furthermore, quantifying the invasiveness potential of NNS can contribute important knowledge towards invasive species biology. In this context, the first step in risk analysis studies is screening (i.e. hazard identification), which aims to identify the NNS that are likely to pose an elevated threat to native species and ecosystems in the risk assessment area and, therefore, warrant more comprehensive (i.e. full) risk assessment. This examines in detail the risks of:

• introduction (entry);
• establishment (of one or more self-sustaining populations);
• dispersal (more widely within the risk assessment area, i.e. so-called secondary spread or introductions); and
• impacts (to native biodiversity, ecosystem function and services, and the introduction and transmission of diseases).

Previously published papers on risk screening of aquatic NNS, and especially those using the most widely-employed ‘-ISK’ decision-support toolkits (see https://doi.org/10.1016/j.envsoft.2020.104900), have attracted mounting interest from the wider scientific community and have been extensively cited (see https://doi.org/10.1007/s11160-019-09562-2; https://doi.org/10.1016/j.scitotenv.2021.147868). However, despite these numerous applications, there remain several knowledge gaps in NNS risk screening with special relevance to the following topics:

• the relative dearth of information on the invasiveness of aquatic NNS in taxonomic groups other than fishes and invertebrates;
• the paucity of risk screening studies focusing on biodiversity hotspots and/or tropical areas;
• the requirement for updated information on species invasiveness within a dynamic risk screening and comparative perspective; and
• the need for a taxon-generic decision-support toolkit for the screening of terrestrial animals and related applications.