Pest plants and animals leave a $1.7 trillion bill

Credit: Shutterstock

They are one of the most harmful environmental forces on earth. They have colonized just about every place humans have set foot on the planet. Yet you may not even know they exist.

We are talking about exotic species. Not little green aliens, but invasive plants and animals not native to an ecosystem that become pests. These can be plants from South America, starfish from Africa, insects from Europe or birds from Asia.

These species can threaten the health of plants and animals, including humans. And they cause enormous economic damage. Our researchrecently published in the journal Nature, puts a number on this damage. We found that globally, invasive species cost US$1.3 trillion (AUD$1.7 trillion) in money lost or spent between 1970 and 2017.

The cost increases exponentially over time. And, disturbingly, most of the costs are related to damage and loss caused by invasive species. Meanwhile, much cheaper control and prevention measures are often overlooked.

An expansive toll

Invasive species have been invading foreign territories for centuries. They come from habitats as diverse as tropical forests, dry savannahs, temperate lakes and cold oceans.

They arrived because we brought them – as pets, ornamental plants or as stowaways on our holidays or through trade.

The problems they cause can be:

Attack of alien invaders: Pest plants and animals leave a chilling $1.7 trillion bill

Yellow crazy ants, like those attacking a gecko, are among thousands of invasive species causing ecological and economic havoc. Credit: Dinakarr, CC0, Wikimedia Commons

  • Ecological, such as causing the extinction of native species.
  • Related to human health, such as causing allergies and spreading disease.
  • Economic, such as reduced crop yields or destruction of man-made infrastructure.

In Australia, invasive species are one of our the most serious environmental problems and the main cause of extinctions.

Wild animals such as rabbits, goats, cattle, pigs and horses can degrade grazing areas and compact the soil, affecting agricultural production. Wild rabbits invade the burrows of native animals, while wild cats and foxes hunt and kill native animals.

Introduced insects, such as yellow crazy ants on Christmas Island, pose a serious threat to a native species. across Australia, wild bees compete with native animals for nectar, pollen and habitat.

invasive fish compete with native species, disturb aquatic vegetation and introduce disease. Some, like plague minnowsfeed on frog eggs and tadpoles and attack native fish.

Environmental weeds and invasive fungi and parasites also cause great damage.

Of course, the problem is global and examples abound. In Lake Victoria in Africa, the huge carnivore Nile perch—introduced to stimulate fishing—destroyed over 200 of the 300 known species of cichlid fish— prized by aquarists worldwide.

And in the Florida Everglades thousands five feet long burmese pythons swallowed up small native mammals at an alarming rate.

Attack of alien invaders: Pest plants and animals leave a chilling $1.7 trillion bill

Northern Territory wetlands damaged by the invasive swamp buffalo (Bubalus bubalis). Credit: Warren White

money talks

Despite the serious threat posed by biological invasions, the problem receives little political, media or public attention.

Our research aimed to reframe the problem of invasive species in terms of economic cost. But it was not an easy task.

The costs are diverse and difficult to compare. Our analysis looked at thousands of cost estimates, compiled and analyzed over several years in our still growing InvaCost database. Economists and environmentalists helped refine the data.

The results were staggering. We found that invasive species cost the world US$1.3 trillion (AUD$1.7 trillion) lost or spent between 1970 and 2017. The cost largely involves damage and loss; the cost of preventing or controlling invasions was ten to 100 times lower.

Obviously, mastering control and prevention would have avoided the massive damage bill.

Average costs have increased exponentially over time, tripling every decade since 1970. In 2017 alone, the estimated cost of invasive species was over US$163 billion. This is more than 20 times more than the combined budgets of World Health Organization and the The United Nations in the same year.

Perhaps more alarmingly, this massive cost is a conservative estimate and likely just the tip of the iceberg, for several reasons:

  • We only analyzed the strongest data available; if we had included all published data, the cost would have been 33 times higher for the 2017 estimate.
  • Some damage caused by invasive species cannot be measured in dollars, such as carbon uptake and loss of ecosystem services like pollination.
  • More impacts were not correctly estimated
  • most countries have little or no relevant data.
Attack of alien invaders: Pest plants and animals leave a chilling $1.7 trillion bill

In Africa, many beautiful cichlids have been decimated by the Nile perch. Credit: Shutterstock

Prevention is better than cure

National regulations to control invasive species are clearly insufficient. And because alien species do not respect borders, the problem also requires a global approach.

International cooperation should include financial assistance to developing countries where invasions are expected to increase significantly over the next few decades and where regulation and management are who misses the most.

Proactive measures to prevent invasion must become a priority. As the old saying goes, prevention is better than cure. And it has to happen early – if we miss the start of an invasion, control in many cases is impossible.

More and better research on the economic costs of biological invasions is essential. Our current knowledge is fragmented, hampering our understanding of patterns and trends, and our ability to effectively manage the problem.

We hope that quantifying the economic impacts of invasive species will mean that political leaders will start to take notice. Certainly, the confirmation of a AUD 1.7 trillion bill should be enough to get the ball rolling.

Aquatic invasive species cause billions of dollars in damage

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