A review of ranking systems for new plant threats in EU Member States and Third Countries: concepts and applications

A review of existing ranking systems for plant threats developed by EU Member States and Third Countries is presented in this report. The analysis of these ranking systems is done according to six main topics: 1) purpose of the ranking, 2) characteristics of pests, 3) patterns and features of the systems, 4) structure of the systems in terms of point scales and score aggregation, 5) treatment of missing data, expression of uncertainty and validation of the system via comparison with expert ranking or judgments, and 6) possibility of running several scenarios and application of different weightings. Common features between these systems as well as their main differences are highlighted. General recommendations are put forward, especially with a view to the development of a future ranking system for new non‐regulated pests.