The red fire ant (Solenopsis invicta) is considered one of the most dangerous ants in the world, not only because of the environmental damage it is causing as an invasive species but also because the bites of this small insect equipped with a sting and venom are very painful. and can cause skin pustules and serious (even fatal) reactions.
This species, also known in Argentina as red ant, is native to South America but has become a pest in the southern United States (where it accidentally arrived in 1930), Australia, Taiwan, the Philippines, and the southern Chinese province of Guangdong.
Monitoring the expansion of this ant has become a topic of international scientific interest and now a study led by experts from the Institute of Evolutionary Biology (IBE), a joint center of the Higher Council for Scientific Research (CSIC) and the Pompeu Fabra University (UPF) , has documented for the first time the existence of nests of this species in Europe.
Specifically, as detailed in an article published this week in the journal Current Biology, 88 nests of the red fire ant (Solenopsis invicta) have been identified spread over about 5 hectares near the city of Syracuse, in Sicily, Italy. These are invasive colonies that could come, according to the genetic analyzes of the study, from China or the United States, where it is also an invasive species.
The research has been led by Roger Vila, a scientist at the IBE, while the first signatory of the article is Mattia Menchetti, INPhINIT 'la Caixa' predoctoral researcher at the IBE; in addition to the participation of researchers from CREAF, the University of Parma Studies (Italy) and the University of Catania.
The ecological models carried out by the study show alarming predictions about the colonization of this ant in Europe and its possible expansion across the continent, which could be facilitated by climate change.
Solenopsis invicta is a species that is causing, as an invasive species, "a great impact on ecosystems, agriculture and human health," highlights the IBE. "Its bite is painful and irritating and can generate pustules and allergic reactions, potentially producing anaphylactic shock," recalls this research center based in Barcelona.
In less than a century, this ant has established itself in much of the United States, Mexico, the Caribbean, China, Taiwan, and Australia, and has only been eradicated in New Zealand. Its presence in the United States causes an estimated loss of close to six billion euros a year, while countries like Australia allocate millions to its eradication, still without success.
Prior to this study, specimens of S. invicta had occasionally been intercepted in imported products in Spain, Finland and the Netherlands, but its establishment in Europe had never been confirmed.
Through genetic analysis, the study concludes that the population detected in Sicily probably comes from China or the United States, but the route of entry is unknown. The colonies are located in a suburban area of the city of Syracuse made up of an estuary and a natural park. It is an isolated area, so it is considered unlikely that it was the first entry point to the island. The team concludes that the entry point must have been a transit area with human activity, such as the commercial port of the city of Syracuse.
Analysis of wind direction indicates, in this sense, that some flying queen ants could have arrived from the northwest, where the port of Syracuse is located and where the team recommends monitoring this invasive species.
Using distribution models developed in collaboration with CREAF, based on current environmental conditions, the study concludes that this invasive species could establish itself in approximately 7% of the European continent.
The conclusions reveal that half of the urban areas in Europe would be suitable for its establishment due to their environmental conditions. Large cities such as Barcelona, Rome, London or Paris could see their activity altered by this invasive species, which can affect people's lifestyles due to its abundance and aggressiveness.
Mediterranean coastal cities, highly connected by seaports, are the most suitable for S. invicta, which would favor its spread. If climate change predictions are considered, the scenario worsens seriously because more of Europe would become suitable for the species.
“Coordinated efforts for early detection and rapid action in the region are key to successfully managing this new threat, before it spreads uncontrollably,” warns Roger Vila, principal researcher at the IBE in the Diversity and Evolution group. of butterflies, who led the study.
“Citizen science can play a key role in detecting S. invicta, given that it is frequently found in urban and peri-urban areas. It is possible to detect these ants due to their painful bites and the characteristic mounds of their nests, although confirmation from an expert is essential,” explains Mattia Menchetti.
Given the dispersal capacity of this invasive species and the presumed existence of an unknown first point of introduction, the team recommends that monitoring be extended to a larger geographic scale.
Reference article: Menchetti M., Schifani E., Alicata A., Cardador L., Sbrega E., Toro-Delgado E., Vila R. (2023). The fire ant Solenopsis invicta is established in Europe. Current Biology. DOI: https://doi.org/10.1016/j.cub.2023.07.036.
This research has received support from the 'la Caixa' Foundation, among others.
