Invasive species are spread around the world as people, animals, cargo, and ships travel from place to place. The changing climate is increasing the spread of invasives. With temperature changes in both air and water, species are shifting locations to find their preferable environments. Some species are more flexible to various habitats and diets, which allows them to adjust to new environments more readily. Unfortunately, this can negatively impact native species that are more sensitive to variations.

Invasive species, by definition, cause significant environmental, social or economic damages. The economic toll of these invasions is steep. In Ontario alone, municipalities and conservation authorities are estimated to spend $50.8 million per year on invasive species. For example, the Emerald Ash Borer, the most costly invasive species in Ontario, has devastated North American ash tree populations. In the United States, it is estimated that around 17 million trees will need to be removed in the coming decade at a total cost of 10.7 billion USD or more.

Biological invasions also have significant economic impacts on the Canadian Forest Sector. The CFIA estimates Canada’s annual timber losses due to invasive species at 61 million cubic metres (m³), equivalent to $720 million in losses. Several invasive species are having negative impacts on Canadian forests including Mountain Pine Beetle (MPB), Beech Bark Disease, and dog-strangling vine.

Globally, the cost of insect invasion alone is estimated at around 70 billion USD per year (Bradshaw et al., 2016).

Despite the enormous global damages of biological invasions, economically, socially and environmentally, lack of clear public understanding of the outcomes associated with these invasions creates barriers to effective management and mitigation. A clear and synthesized collection of current knowledge on the global economic costs of invasive species could provide a better public understanding of these costs and facilitate action and policy.

What is Invacost?

Analyzing the impacts created by invasives can aid in the creation of management protocols and policies to help with education and the reduction of negative effects. Invacost is a global, online database created to harmonize data on the cost of worldwide biological invasions. This living, publicly available database uses a systematic, standardized methodology to collect information from peer-reviewed articles and grey literature. As a living database, updates are continuously released, allowing for up-to-date information. This database provides an information base for global research, management efforts and data-driven policymaking.

Neobiota, the open-access online journal, has published a special issue on the economic costs of biological invasions around the world. The official report, intended for the French government, was aimed to raise awareness about the necessity to limit the multidimensional impacts from biological invasions in our societies, as well as provide general and specific recommendations about the findings. After 8 years of work, the issue, titled InvaCost, contains 19 studies with 61 co-authors.

The original team of researchers searched and sorted through over 1,800 articles from grey and peer-reviewed literature to collate and depict economic cost estimates. Explicit estimations of costs and expenditures associated with invasive species were extracted and given descriptors seen in table 1 including country, taxonomy and cost-type. These categories facilitate the search of the database for analysis of factors such as cost based on taxonomic group, geographical area or impacted sectors. Invacost currently contains over 13,500 cost entries representing at least 970 invasive species and 176 countries worldwide. Currently, there are 64 descriptive fields that can be divided into 4 major groups: references, taxonomy study information, and cost typology. This database can be found on the figshare website here. In 2021, an R package was introduced specifically tailored to analyze the Invacost database.

Data Gaps

The original methodological paper on Invacost identified data gaps to be addressed in the future. The first is the lack of non-digital and non-English sources. This gap was addressed in 2020 with the addition of 11 new languages, however, data biases still exist and some regions such as the United States are still more extensively covered than others. The second gap was information on the status of the species in the collected data. Were these species still established or eradicated after management efforts? The authors suggested establishing a connection between Invacost and other databases such as the GRIIS that provides verified information on the continued presence of introduced and invasive species for most countries. A third data gap they identified was information on “non-market values” such as the value lost through impacts on native species. Certain values, like ecosystem function, are difficult to put a dollar value to and so can be underestimated.

What has been found?

Analysis of the Invacost database has expanded our understanding of the economic costs of biological invasions. The report uncovers data from the last 50 years to assess the amount of money spent on damages caused by invasive species. The estimated cost of invasive species is astronomically high, with a total global expenditure of 1.288 trillion USD since 1970 with 162 billion spent in 2017 alone. In North America, the amount spent between 1960 and 2017 totals $1.26 trillion US, and has increased from $2 billion per year in the 1960’s, to $10 billion per year in the 2010’s.

These costs are constantly increasing, doubling every 6 years. They also found that the costs of biological invasions increase at a steeper rate than the costs of management. In 2017, the economic costs of damages were 10x higher than management costs. The results also suggest that these costs have likely been underestimated.

The North American Study revealed that the most economically impacted habitat in North America was terrestrial with invasive species categorized as impacting semi-aquatic determined to be the second most damaging. The most heavily impacted sector was the Agricultural Sector, incurring a total reported cost of US$ 527.07 billion. The study also revealed that damage costs far outweighed either management costs or mixed costs within North America. The Global Study revealed that societies worldwide have been paying much more for the post-introduction management of alien species investing relatively very little in the prevention of biological invasions.

Up to date information on the economic costs by taxa or region can be found in the Invacost living figure. Discussing this issue in terms of monetary value creates an approach that researchers and other practitioners can use to help with assessing and communicating impacts. This is one of many tools that can be used to support these assessments.

Having evaluations such as InvaCost allows economists to become aware of the burden created by global trade. This awareness can lead to more conversations about the cost versus benefit of this trading system, as well as how international travel and tourism impacts biodiversity.