Invasive alien species pose significant threats to biodiversity and ecosystem health, simultaneously impacting human and social well-being. They are species accidentally or intentionally introduced by humans to biogeographic regions where they lack an evolutionary history, often for commercial or recreational reasons. They are characterized by their ability to spread aggressively, thereby becoming invasive and in many cases severely impacting both natural and social environments.

Recent comprehensive efforts to document and synthesize reported monetary costs across all ecosystems and taxa globally have revealed staggering figures. Over the past fifty years, the cumulative cost has escalated to an alarming $1.288 trillion worldwide, with Europe incurring expenses of $140.20 billion and the Nordic countries facing costs of $8.35 billion (Diagne et al., 2021; Haubrock et al., 2021; Kourantidou et al., 2022). These figures are likely conservative and understated, representing only the documented minimum of the monetary costs incurred.

Our study focused on invasive species in urban areas revealed a reported cost of US$ 326.7 billion between 1965 and 2021. The study, which found 61 invasive species across 24 countries, challenges our understanding of the true scale of the economic consequences of biological invasions in urban environments. The documented costs in urban areas represent approximately 15% of the total global economic impact of invasive species, estimated to be at least US$ 2.2 trillion. Urban areas, covering only between 0.6% and 3% of the Earth’s surface, contribute significantly to the overall monetary impact associated with biological invasions.

The study also reveals relevant gaps in our understanding of the economic impact in urban areas. Most costs are strongly driven by a few species, such as Formosan subterranean termite, emerald ash borer, red imported fire ant, Mediterranean fruit fly, and feral pigeon. Other species probably have their costs underestimated, for example, Aedes mosquitoes. Moreover, most costs are concentrated in the United States of America, China, and Austria (respectively, US$ 261.5 billion, 518 million, and 169 million). 73 countries with occurrences of costly species in urban areas lack reported costs in the literature, implying a substantial underestimation of the global monetary impact.

The management of invasive species in urban areas presents complex challenges, with costs frequently caused by damage rather than proactive management. The study underscores the importance of proactive measures to reduce and prevent future impacts associated with biological invasion in urban areas.

These species can damage buildings, monuments, and public infrastructure, while also affecting stored food, causing allergies, and transmitting diseases. The impacts are particularly severe in densely populated areas where they affect a large number of people swiftly. Therefore, it is crucial to implement measures to prevent the introduction of invasive species and to detect and control them promptly. The study calls for stronger engagement with stakeholders, and more focused efforts to assess and report the costs related to the biological invasions in urban areas. Recognizing the financial drain caused by invasive species in urban environments enhances public and political awareness, fostering a collective effort to address this urgent global issue.

Dr. Kourantidou extends her gratitude to all co-authors of the study, with special thanks to Dr. Gustavo Heringer for leading the research and Dr. Franck Courchamp for pioneering the InvaCost project, which generated the database from which the numbers and estimates cited in the text are derived.

This post is based on the study published in:

Economic costs of invasive non-native species in urban areas: An underexplored financial drain. Gustavo Heringer, Romina D. Fernandez, Alok Bang, et al. Science of the Total Environment, January 2024. DOI: https://doi.org/10.1016/j.scitotenv.2024.170336 

Other references cited in the text include the following:

Diagne, C., Leroy, B., Vaissière, A.-C., Gozlan, R. E., Roiz, D., Jarić, I., Salles, J.-M., Bradshaw, C. J. A., & Courchamp, F. (2021). High and rising economic costs of biological invasions worldwide. Nature, 592(7855), 571–576.

Haubrock, P. J., Turbelin, A., Cuthbert, R. N., Novoa, A., Angulo, E., Mejia, L. B., Bodey, T., Capinha, C., Diagne, C., Essl, F., Golivets, M., Kirichenko, N., Kourantidou, M., Leroy, B., Renault, D., Taylor, N., Verbrugge, L., & Courchamp, F. (2021). Economic costs of invasive alien species across Europe. NeoBiota, 67, 153–190.

Kourantidou, M., Verbrugge, L. N., Haubrock, P. J., Cuthbert, R. N., Angulo, E., Ahonen, I., … & Courchamp, F. (2022). The economic costs, management and regulation of biological invasions in the Nordic countries. Journal of Environmental Management, 324, 116374.

Image credit: AI image created by author with DALL-E