These “exotic” species that humans have taken, voluntarily or not, from their original ecosystems create problems in their new habitats and tackling them has cost at least $ 1.28 trail since 1970, according to this report published in the journal Nature, which analyzed thousands of data included in the public database InvaCost.
Plants, insects, birds, fish, mollusks, microorganisms, mammals … Man faces these invasive species, fighting against their proliferation, but, above all, against the damage they cause on terrestrial and maritime surfaces.
These degradations affect all ecosystems: from the American forests attacked by the Asian strata to Australian agriculture, pressured by the rabbit. Without forgetting the infrastructures threatened by termites, the ducts obstructed by the zebra mussel and even the real estate devaluation in Hava due to the coqui frog, whose corner can reach 100 decibis.
According to InvaCost data, incomplete, among the species that cause the most damage are rats, the hairy lizard, – a lepidopteran native to Asia that attacks trees throughout the northern hemisphere -, fire ants and, above all, all mosquitoes, due to the medical treatment required by the diseases transmitted by these insects.
The tiger mosquito originating in Southeast Asia, for example, is one of the worst invasive species in the world, having spread mainly across Europe, carrying chikungunya, dengue and zika.
In addition to the “phenomenal” cost, “worrying about its constant growth, with an annual average that doubles every six years and triples every decade,” says the study’s lead author, Christophe Diagne, from the French Ecologie laboratory, Systmatique et Evolution.
– Exponential increase –
This increase is partly due to “an exponential increase in invasive species”, explains the director of the laboratory, Franck Courchamp.
Invasive alien species are among the top five causes of nature destruction, according to the 2019 report by the UN biodiversity experts (IPBES), which indicates 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 make these species more and more established” in the territories, adds Courchamp.
The study’s authors advocate preventive measures to limit its damage and costs. Among them is early detection.
In the meantime, they ask to complete the InvaCost database, with the most recent invasions, such as the cartridge caterpillar, from the American continent, which devastated African plantations before settling in Asia and Australia.
“This species is likely to be more costly than the ten we classify,” adds Courchamp.
Among those already mentioned, there is the domestic cat, which “accompanied the navigators when they explored the planet”.
Although it is a “particular” case, the cat is still an “invader on almost every island in the world”, according to Courchamp, who describes him as a fearful predator of birds and reptiles.
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