Fortress Europe has fallen: One of the world’s worst invasive species – the red fire ant – has established pioneer colonies in Sicily, researchers have found. From there, the rabid crawlers could now spread further across the continent, as there is considerable potential for this. As in their previous areas of conquest around the world, the insects could then cause enormous ecological and economic damage to us and threaten people with their poison. Only through consistent control measures could the invasion be thwarted, say the researchers.
Its scientific name became the program: Solenopsis invicta means “The Undefeated Fire Ant”. The species, which originally came from South America, was able to conquer numerous new habitats after being introduced by humans. The successful triumph of the red fire ants is based on their aggressive behavior, which they show both towards other ants and towards humans: Anyone who irritates the crawlers will feel their powerful claws and a stinger with strong poison that burns like fire. This can not only be very painful, but can also lead to allergic reactions and even shock.
Over the last hundred years, the red fire ant initially spread widely in North America and then finally reached China and Australia. Experience shows that they displace native ant species in the areas they conquer, threaten many other animals with their feeding pressure and harass people. The associated damage is also enormous economically. The fire ant is therefore considered one of the worst invasive species in the world.
Now Europe has also been hit
Surprisingly, however, Europe had so far been spared from the invasion. But that has now changed. “Scientists have feared that this would happen for decades,” says lead author Mattia Menchetti from the Institute for Evolutionary Biology in Barcelona. The possible “bridgehead” of the fire ant invasion in Europe is now the Italian island of Sicily. After seeing suspicious ant photos from there, researchers visited the region to determine the species’ identity and collect samples.
This turned out to be Solenopsis invicta. The scientists found a total of 88 red fire ant nests in a 4.7 hectare area near a suburb of the city of Syracuse. Conversations with locals provided information about how long the invaders have been established there: “They had noticed strange bites since at least 2019 – so the ants have probably been there for a while. And the actual extent of the affected area is probably significantly larger than previously known,” says Menchetti. How and from where the animals got to the site remains unclear. However, they may have reached the island via the port of Syracuse. A genetic study of the queen ants points to an origin from either the USA or China.
In order to gain clues as to how the invaders could now spread further, the scientists analyzed the local wind patterns in Sicily. It is known that the wind plays an important role in the distribution of the winged sexual animals of ants. They also created a comprehensive model to determine how suitable the rest of Europe and the Mediterranean might be for the species – and whether climate change will play a role.
Lots of potential for spread in Europe
The results showed that Sicily could actually become the nucleus of further expansion. The researchers say that the favorable living conditions for S. invicta in urban areas are particularly alarming: 50 percent of European cities offer good conditions for the invaders. “What is also worrying is that many cities, including London, Amsterdam and Rome, have large seaports, which could once again enable the ants to spread rapidly,” says senior author Roger Vila from the Institute for Evolutionary Biology in Barcelona.
But what can be done to get the threat under control? “We need a coordinated approach, and we need it now,” says Menchetti. First, the extent of the infestation must be determined more precisely. Measures should then be carried out to eradicate the nests. After that, the sites need to continue to be monitored to ensure there is no recurrence, the scientists say. Corresponding approaches have already shown success in New Zealand. “Citizens can also play a very important role in this,” says Menchetti. The team is therefore planning to organize citizen science programs in which people specifically look out for S. invicta and report finds along with photos. “More awareness needs to be created about this problem, which has now reached Europe,” said Menchetti.
Source: Cell Press, Spanish National Research Council (CSIC), specialist article: Current Biology, doi: 10.1016/j.cub.2023.07.036