Invasive species such as mosquitoes, rodents and even domestic cats cost humanity dearly: about $ 26.8 billion annually, according to a study published Wednesday that warns that the amount will continue to rise.

These “exotic” species that man voluntarily or not removed from their original ecosystems create problems in their new habitats and coping with them has cost at least 1.28 billion dollars since 1970, according to this report published in the journal Nature that analyzed thousands of data included in the public database InvaCost.

Plants, insects, birds, fish, mollusks, microorganisms, mammals … Man faces these invasive species by fighting against their proliferation, but above all against the damage they cause either on land or sea surfaces.

These degradations affect all ecosystems, from American forests attacked by the Asian longicorn to Australian agriculture, weighed down by the rabbit. Not forgetting the infrastructures threatened by termites, the pipes blocked by the zebra mussel and even the depreciation of real estate in Hawaii due to the coqui frog, whose song can reach 100 decibels.

According to incomplete InvaCost data, among the most expensive species are rats, the hairy lizard, – a lepidopteran native to Asia that attacks trees throughout the Northern Hemisphere -, fire ants and above. all mosquitoes, due to the medical treatment required by the diseases they transmit.

For example, the tiger mosquito native to Southeast Asia is one of the worst invasive species in the world, which spread mainly in Europe carrying chikungunya, dengue and Zika.

In addition to the “phenomenal” cost, “its constant growth is worrying, with an annual average doubling every six years and tripling every decade,” according to the study’s lead author, Christophe Diagne, from the French laboratory Ecologie, Systématique et Evolution.

– Exponential increase –

An increase that is due in part to “an exponential increase in invasive species”, according to Franck Courchamp, director of the laboratory.

Invasive alien species are among the five main causes of destruction of nature, according to the 2019 report of the UN experts on biodiversity (IPBES), which accounts for a 70% increase in their number since 1970 in the 21 countries examined.

“International trade will cause more and more species to be introduced and climate change will cause them to establish more and more” in the territories, according to Courchamp.

The study authors advocate limiting harm and costs with preventive measures, such as early detection.

Meanwhile, they defend the completion of the InvaCost database, with more recent invasions such as the fall armyworm, from the American continent, which massively destroyed African crops before settling in Asia and Australia.

“This species is likely to turn out to be more expensive than the ten we classified,” according to Courchamp.

Among the animals mentioned is the domestic cat, which “followed the navigators when they explored the planet.”

Although it is a “particular” case, the cat is still an “invader in almost all the islands of the world”, according to Courchamp, who describes it as a fearsome predator of birds and reptiles.

abd / app / mb

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