Integration of science and group decision making to derive exotic species priorities

Non-native plant pests and pathogens enter the United States at an alarming rate. Pathways for entry are varied, and, while only a small percentage of exotic species prove to be invasive, early detection of successful invaders is critical to minimizing the impact of these species on agricultural and natural resources. Early detection surveys require a significant amount of resources and must therefore be directed at species that are considered high priority. Selection of exotic species for survey is a complex decision, which involves careful consideration of biology, potential for introduction and spread, and anticipated negative impacts resulting from a successful introduction. A set of criteria encompassing the aforementioned factors was developed and arranged into a logical hierarchy. 139 exotic plant pests and pathogens were evaluated against the criteria set and prioritized using the analytic hierarchy process. The resulting pest rank was not sensitive to moderate changes in the weights of the criteria. High-ranking species were selected as targets for early detection surveys implemented on a national level. The analytic hierarchy process provided the structure and transparency necessary for group decision making in the public sector and increased the efficacy of early detection by using threat level to prioritize exotic plant pathogens and pests.