Invasive species cost the US $21 billion per year, study finds

Invasive species are increasing worldwide due to mounting global trade, and a new study has found that these mammals, bugs and bacteria cost the US economy more than $21 billion per year, with agriculture the sector most affected.

"The biggest proportion of these costs are actual damages,” said Drew Kramer, a biologist at the University of South Florida and co-author of the study in the journal Science of the Total Environment.

Researchers used a global database called InvaCost to assess only “observed, highly reliable costs related to invasive species,” from 1960 to 2020, according to the study.

Data showed that in the 1960s, annual costs of invasive species were $2 billion. By 2010 to 2020, these costs were $21.08 billion per year.

Just what costs so much? Invasive species can destroy crops, the environment, and kill off native animals.

The majority of the costs (73%) were “related to resource damages and losses,” said the study.

The top three most expensive invasive species in the southeastern United States are feral pigs, citrus canker, and fire ants.

"One of the most interesting things we found to me is how much more of the cost is damages versus money spent, to try to prevent those damages," Kramer said.

Since invasive species can't ever be kept out -- in a global economy like ours -- Kramer said policymakers could prevent some economic losses by spending on better management.

One example: a program in place to contain the Mediterranean fruit fly by releasing sterile males, which cut down on the population.

"That costs on the order of $10 million a year, but it has been successful in preventing any establishment since 2011," he said.

Kramer, an assistant professor in the Integrative Biology Department at USF, says spending that $10 million probably saves farmers hundreds of millions.

The same goes for citrus canker, which is caused by a bacterium common in Asia.

“Something like citrus canker in Florida destroys part of the crop and that's going to cost farmers millions of dollars whether it's replacing trees, or fruit they can't sell," added Kramer.

That's why researchers say spending more on programs that prevent plants, bugs and critters from getting established in new places is more important than ever.

Find the full study here.

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