Invasive amphibian and reptile species cost world $17bn in three decades, study finds

Scientists call for better measures to limit global transport of invasive species and to enable early detection of invasions

Invasive amphibian and reptile species have cost the global economy at least $17bn (£14bn) in the period between 1986 and 2020, according to a new study.

The findings, published in the journal Scientific Reports, highlights the need for better policies to limit the spread of such species which spread beyond the regions they are native to.

Studies have shown that species invasions can lead to damage including the displacement or extinction of native species, the spread of diseases, as well as crop losses.

Scientists including Ismael Soto from the University of South Bohemia in the Czech Republic examined the worldwide costs due to invasion by amphibians and reptiles – herpetofauna – using data from the InvaCost database, which compiles estimates of the economic costs of species invasions.

The data used in the study was taken from peer-reviewed articles, documents on governmental, academic as well as non-governmental organisation webpages and documents retrieved from biological invasion experts.

Scientists found that between 1986 and 2020 the total cost of reptile and amphibian invasions exceeded $17bn.

Of this, amphibian invasions alone cost $6.3bn and reptile invasions separately cost $10.4bn.

Invasions involving both amphibians and reptiles cost $0.3bn, the study noted.

Over 96 per cent ($6bn) of costs due to amphibians were due to a single species, the American bullfrog (Lithobates catesbeianus), while 99 per cent ($10.3bn) of costs attributed to reptiles were solely caused by the brown tree snake (Boiga irregularis), researchers say.

In the Pacific Islands, scientists say the brown tree snake has generated “significant economic costs through island-wide power outages, resulting in a loss of $4.5m per year as well as ecological impacts through the extirpation of most endemic birds via depredation.”

They say about 99 per cent ($6.3bn) of costs due to amphibians were associated with managing invasions, for example by eradicating invasive species.

And over 96 per cent ($10bn) of costs due to reptiles were associated with damages caused by invasions, such as crop yield losses.

For amphibian invasions, they say 96 per cent, or $6bn, of the economic costs were incurred by European countries while 99.6 per cent – $10.4bn – of costs due to reptile invasions were incurred by Oceania and Pacific Island countries.

Scientists call for a reduction in the economic costs of amphibian and reptile invasions by investing in measures to limit global transport of invasive species and to enable the early detection of invasions.

They say this could reduce the need for long-term management of species invasions and the scale of damage incurred.

“A greater effort in studying the costs of invasive herpetofauna is necessary for a more complete understanding of invasion impacts of these species. We emphasise the need for greater control and prevention policies concerning the spread of current and future invasive herpetofauna,” scientists wrote in the study.