Addressing the economic costs of invasive alien species: some methodological and empirical issues

The impact of invasive alien species (IAS) is evaluated by calculating the damages to the use and non-use values of ecosystem services caused by alien species, using estimates provided by a recent study undertaken for the Republic of Ireland and the Province of Northern Ireland. Large discrepancies are revealed between the scale of these damages and current outlays on prevention and control measures. This prompts an examination of the reasons why most high-income economies under-invest in biosecurity. A combination of environmental and economic factors related to the public good characteristics of biosecurity is shown to frustrate efforts to address this major global threat to biodiversity and well-being. Some proposals for overcoming the constraints on biosecurity spending created by the public good nature of its provision are reviewed.