Harmonia + and Pandora +: risk screening tools for potentially invasive plants, animals and their pathogens

Given the large number of alien species that may potentially develop into invasives, there is a clear need for robust schemes that allow to screen species for such risks. The Harmonia (+) framework presented here brings together 30 questions that refer to distinct components of invasion. Together, they cover the stages of introduction, establishment, spread, and multiple kinds of impacts, viz. referring to the health of the environment (including wild species), cultivated plants, domesticated animals and man. In a complete assessment, input is provided by choosing among predefined ordinal answers and by supplementing these with textual clarification. Uncertainty is covered by indicating levels of confidence. By converting answers into scores, which are then condensed into summary statistics, Harmonia (+) allows for quantitative output on stage-specific and general risks. Test assessments on five species emerging in Belgium showed the perceived environmental risks of Procambarus clarkii to be highest (0.72), and that of Threskiornis aethiopicus to be lowest (0.13). Given the considerable parallels that exist between invasive alien species and emerging infectious diseases, we additionally created Pandora, which is a risk analysis scheme for pathogens and parasites. It consists of 13 key questions and has the same structure as Harmonia (+). Since diseases play a paramount role in biological invasions, results of Pandora assessments may feed into Harmonia (+) through a slightly adapted, host-specific version named Pandora (+). Harmonia (+), Pandora and Pandora (+) may be used both for prioritization purposes and for underpinning detailed risk analyses, and can be consulted online through http://ias.biodiversity.be.