The red fire ant, native to South America, spreads “alarmingly quickly”, earning it the top spot among the world’s invasive animal species, said researchers, including Mattia Menchetti from the Institute of Evolutionary Biology in Spain.
Their study warns that the species, known for its painful sting, could soon spread all over the continent.
Although it originated in South America, the red ant, scientifically known as Solenopsis invicta has quickly established itself in most parts of the globe, flying into wind streams to travel farther on the local level.
“There are a vast number of alien ant species currently establishing in Europe, and the absence of this species was kind of a relief,” Dr Menchetti said. “Finding this species in Italy was a big surprise, but we knew this day would come,” he said.
Previous research has described how humans have helped the ant species named after its most infamous characteristic – its stings – spread via the maritime trade industry and by shipping plant products.
Such activities have helped the species establish itself in Australia, China, the Caribbean, Mexico and throughout the US in less than a century.
However, Europe has evaded them for longer than expected – until now.
“For decades, scientists have feared that it would arrive. We could not believe our eyes when we saw it,” said Dr Menchetti, one of the authors of the new study, documenting the first discovery of the ant in the continent.
In the research, the results of which were published recently in the journal Current Biology, scientists took a trip to Sicily to confirm the ants’ identity and collect samples after seeing photos taken of the species in the region.
They found 88 ant nests during their survey in total in a 4.7-hectare area next to a river.
Some of these nests housed thousands of worker ants.
Researchers learned from local people in the region that many had been getting stung – frequently – by the ants for several years.
“The locals have been experiencing these painful things since at least 2019, so the ants have probably been there for a while,” Dr Menchetti said, adding that the “real extension” of the invasion is likely larger.
Comparing the DNA of the Sicilian red ant queens with those of ants from other parts of the world, researchers said the particular population of the invasive species in Sicily likely came from either the US or China.
Scientists also modelled how the species is likely to spread to other parts of Europe based on local wind patterns in Sicily and by analysing how suitable the rest of the continent and the Mediterranean area will be for the ants.
They deemed about 7 per cent of Europe to be suitable for S invicta under current environmental conditions.
However, they warned that the climate crisis can expedite their spread further, with urban areas particularly at risk.
Based on the new study, scientists said half of Europe’s cities are vulnerable to the stinging ant’s invasion.
“This is especially concerning because many of the cities, including London, Amsterdam, and Rome, have large seaports, which could allow the ants to spread rapidly to more countries and continents,” explained study senior author Roger Vila.