Harm from invasive alien species 'costs billions every year', French study shows

French scientists estimate that invasive species – alien species introduced by humans to a new environment –have cost a staggering 1.3 trillion dollars in damage over the past five decades.

A new report published in the journal Nature assessed the economic harm being done by all kinds of species –mosquitoes, rodents, insects and even domestic cats – that were either wittingly or unwittingly brought to their new habitats.

It warned that damage to forests, crop yields, human health and national infrastructure – costing $26.8 billion per year – would continue unless decisive action is taken to protect and control biodiversity.

The research project, which took five years, was led by a team from the Ecology, Systematics and Evolution Laboratory, a collaboration including the French National Scientific Research Centre (CNRS), the University of Paris-Saclay, and others.

“This trillion-dollar bill doesn't show any sign of slowing down, with a consistent threefold increase per decade,” warned lead author Dr Christophe Diagne, from University Paris-Saclay.

'Massive' burden
Diagne said the worldwide costs of invasive alien species were so massive that his team spent months verifying their models to ensure they were not exaggerating.

“Our annual global estimates signify the huge economic burden, with the average cost exceeding the gross domestic product of 50 countries on the African continent in 2017, and it's more than 20 times higher than the total funds available for the World Health Organization and UN combined,” Diagne said.

When species as seemingly benign as plants, reptiles, birds, fish or even micro-organisms are introduced to habitats, they can fail to thrive, or they can threaten their new environment.

Examples include Australia's feral European rabbit populations, the Asian long-horned beetle that is devastating American forests and the brown tree snake that has wiped out native birds in Guam.

Increasing global trade brings increases in the number of invasive species.