Any farmer can give you an earful on the exorbitant costs of dealing with invasive species. An international team of researchers has finally tallied the costs, with total invasion management and damages estimated at around $1.3 trillion over the last five decades, according to new research published in scientific journal Nature. The researchers say the estimate is likely a huge underestimate and warn that the problem is probably going to get worse.
An invasive exotic species is one deliberately or unwittingly introduced by humans into a new habitat, where it becomes an environmental menace. As the globe has become ever more connected, these organisms have gained more opportunities to be transported to foreign lands where they often don’t have natural predators. They bring with them crop destruction, disease, waterway contamination, and building damage. What’s more, they are the second leading cause of species destruction the world over.
The international team of researchers found that from 1970 to 2017, managing invasions cost around $66 billion while the cleaning bill for the damages caused by these invaders was almost 13 times higher at $892 billion. And while these damages yielded an annual average of $26.8 billion, the annual bill actually tripled every decade, hitting $162.7 billion in 2017. Costs were highest in the U.S., India, China, and Brazil, but the researchers say this likely reflects where the problems have been most reported. There is little or no data in many other parts of the world.
To put those numbers in perspective, the damages exceeded the gross domestic product of 50 countries on the African continent in 2017, and is more than 20 times higher than the total funds available to the World Health Organization and United Nations combined, the researchers said. And the researchers say they were intentionally very conservative with their estimates but still spent months double and triple-checking their results because they were blown away by the “staggering sums.”
Keep in mind, those cost estimates can only account for what was reported, hence why the researchers believe the true damages are significantly higher. Corey Bradshaw, of Flinders University in Australia, who was part of the study, points out that there are also many unquantifiables from the monetary perspective, such as ecosystem damage and lost productivity, “so it’s still the tip of the iceberg.” He thinks the true costs could be as much as 10 times higher than what they estimate.
The researchers also point out that the problem isn’t well known by the public or policy makers but they hope by shining a light on the “profound” impacts, they hope to raise awareness of the issue and identify the most costly species. Lead author Christophe Diagne of Université Paris-Saclay says the costs are expected to continue increasing as the continued expansion of international commerce and transport generally brings with it more invasive species. Not surprisingly, the problem is also expected to be exacerbated by climate change.
Most of the top offenders are insects, with mosquitoes topping the list, followed by rats, cats, termites, and fire ants. However, the researchers also note that there are big gaps in the data – plants for instance – that have likely skewed the results to some degree. Early detection, better data and preventative measures could reduce costs considerably, the study said. The full study is HERE. Below is a little more info on the top invasive species and their estimated cost.
1. Aedes mosquitoes: approximately $149 billion – The Asian tiger mosquito (A. albopictus) arrived in the United States in the mid-1980s, by way of hitchhiking in used tires shipped from its native Asia. First detected in Houston, it rapidly spread to 40 states. It’s also invaded parts of Europe, South America, Africa and Australia. A. aegypti, or the yellow fever mosquito, is native to sub-Saharan Africa and spread around the world by similar methods. Together, these two mosquitoes cause significant damage to public health by transmitting a range of diseases like Zika, chikungunya, yellow fever and dengue, which accounts for the bulk of their cost.
2. Rattus (rats): approximately $67 billion – These rodents’ worldwide occupation stems from about 3,000 years of hitchhiking on human boats. Once they arrive in a new location, rats often outcompete other small mammals, but can also harm birds and aquatic species. On islands around the world, rats have driven many species to extinction. For example, the Pacific rat, native to mainland southeast Asia, has snuffed out at least 1,000 species of island birds. Rats’ high cost stems from these biodiversity losses, but the rodents also can damage crops, destroy property and transmit disease (like the bubonic plague).
3. Felis catus (cats): approximately $52 billion – Native to Europe and the Middle East, our feline friends have established themselves on all nonfrozen continents. Cats are excellent predators, and can make a quick meal from a variety of prey, from insects to birds. By some estimates, cats kill a billion birds each year in the United States alone (SN: 1/29/13). The bulk of the economic damage inflicted by cats cataloged in Leroy’s analysis comes from their impact on native biodiversity and resulting losses in spending on birdwatching and hunting birds like ducks, pheasants and grouse.
4. Coptotermes formosanus (termites): approximately $19 billion – These subterranean termites native to East Asia have spread around the globe via trade. Termites can thrive wherever there is cellulose (like wood) and moisture, which has helped them quickly establish colonies upon being introduced to a new region. Their appetite for wood can wreak havoc on all kinds of structures, from homes to bridges. While they can also damage crops and tree farms, their high cost in this analysis boils down to their impact on infrastructure.
5. Solenopsis invicta (fire ants): approximately $17 billion – Fire ants usually become the dominant ant species when introduced to a new region, due to their aggressive foraging tactics, which include potent stings and bites. Native to South America, these ants arrived in the United States in the 1930s by boat, most likely carried in soil from the region. They’ve also spread to Australia, New Zealand, China and around the Caribbean. Fire ant colonies have wide-ranging impacts; they can feed on a variety of seedlings, from citrus to soybeans, reduce the size of grazing lands for livestock and bite and sting farm animals and humans. (Sources: SceienceNews, The Guardian, EcoWatch)