Its name is as disturbing as the havoc it causes. The red fire ant (Solenopsis invicta) is one of the most invasive exotic species and the fifth most expensive to combat worldwide.. And to the chagrin of scientists, this dangerous and voracious insect whose painful bite is capable of causing anaphylactic shock in people and killing some animals has already settled in Europe.. This has just been confirmed by research led by the scientist from the Institute of Evolutionary Biology (IBE/CSIC-UPF) Roger Vila, who does not hide his concern about the possibility that it will also settle in Spain.
The proof that this urban ant – it is very comfortable in cities – and very resistant is already in Europe are the 88 colonies that have been found in Sicily, specifically, near the city of Syracuse, in an area of five hectares .
As Roger Vila explains in a telephone interview, the alarm was raised by the residents of the area colonized by this species: “At that point in Syracuse there is a recreational boat dock, it is next to a river and is quite frequented.. The Italian authorities sent some technicians, who took photos and sent them to us. “We were shocked because it looked like it was a red fire ant, so we organized an on-site expedition to study the case and collect specimens.”
Taking advantage of the fact that one of the team members, Enrico Schifani, is Sicilian, he was chosen for that field work: “The local people explained to us that the bites had started at least in 2019, and taking into account how widespread they were already the 88 nests that Enrico has found, at least they have been there since that date. Later, by sequencing its DNA in the laboratory, we have been able to confirm both that it is this dangerous species and determine its possible origin.”
One of the nests located in the Syracuse area
It is not the first time that this insect has been detected in Europe, but it is the first time that its establishment on the continent has been confirmed.. Previously, specimens had been found in imported products in Spain, Finland and Holland.
Based on this analysis and as detailed this Monday in a study published in the journal Current Biology, these ants originally from South America would have arrived on our continent from China or the United States, where they are widely established, as well as in areas of Australia, where were detected at the beginning of this century and, according to Vila, they are threatening the celebration of barbecues, a widespread custom there.. “One of the problems of this ant is that it lives very well in urban and anthropized environments: it loves gardens, the grass of swimming pools or homes.. And it has an enormous density of nests that, in addition, are very large since one can only have tens of thousands of ants, while the nests of other species tend to be smaller.. And it's not usually an isolated bite, before you can run away, 10 or 15 ants have climbed up your leg.”
The biologist remembers that a similar problem has occurred with the tiger mosquito, another invasive species that has spread throughout our country: “It happens to me in my own garden, in Cardedeu, near Barcelona.. Before, during the day you could go out because there were no mosquitoes to bite you, and now you have to put on insect repellent all the time, it's a hassle and you end up not going out, especially in the afternoon. And the red ant is even heavier than the tiger mosquito,” he points out.
A sting similar to that of the Asian wasp
The sting of the red fire ant, Vila compares, is equivalent to that of the Asian wasp in its effects: “It is very painful and irritating. This ant injects substances called alkaloids, but depending on the person, they cause a greater or lesser reaction.. The normal thing is that you get a rash and it ends up going away after a few days, but in a low percentage of the population it causes anaphylactic shock, it is something that has happened. If you go quickly to the hospital and they inject you with cortisone or adrenaline, the reaction stops, but if not, it could cause death.. But I don't want to cause panic, because serious reactions are very occasional,” says the biologist.
A bite from this ant
In Spain, he explains, we also have some ants that sting, “but they are practically not found in cities, they are usually in natural spaces and they can sting if you put your foot near a nest, but this is something that does not usually happen.”
Their analysis also concludes that the European continent has a good chance of becoming a comfortable home for S. Among the most suitable cities, Barcelona and Madrid stand out, but also Rome, Paris and London: “We have done climate models to determine its possible expansion, and it seems that it could be distributed mainly throughout a good part of the urban areas of southern Europe and northern Europe. of Europe where it is not extremely cold, basically the main coastal cities of the Mediterranean and other large cities that have large parks and not extreme cold. Barcelona is perfect for expansion but almost all urban areas are suitable, and with climate change, the area in which it could expand increases a lot.”
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For this reason, he explains, “in the countries that it has invaded, people end up spending a lot of money to try to eradicate it from their cities and their gardens, and it is complicated because they are very large colonies and you have to kill the queen, who never leaves the nest. , so in many cases you have to pay a service to eliminate it. The best method is to use poisoned baits so that the worker ants take them into the nest, feed them to the queens and they die,” he says.
But an added problem is that this species has two types of colonies: with a single queen or with many queens, like those that have arrived in Italy, “so to eradicate these nests you have to kill them all, and also, having many queens, they are bigger nests.
Cities are not the only habitat in which it makes its home. It also likes to live in natural environments, in humid areas, and it is precisely in these ecosystems where it displays one of the abilities that makes it so resistant: “As they usually live in flood-prone areas, they hook each other with their bodies, forming a raft. of hundreds or thousands of individuals that float, with the queen ants on top, so that when there is a flood, many species of ants drown but they survive.
A floating island of red ants, which join together to form a raft to survive floods
How did they get to Sicily? Roger Vila admits that they are not sure: “What had happened on other occasions was that it had been detected in ports, airports and places of commerce, in material arriving from other countries.. Then it is eliminated, which is very important because it has to be done conscientiously, although even so there are many invasive species that escape us and end up establishing themselves,” reviews the biologist, who affirms that one of the main forms of dispersion is the pots of the floors.
“With this red ant, we believe that they did not reach the affected area directly because there is no trade. Most likely they come from the port of Syracuse, which is a few kilometers away and, furthermore, the wind usually comes from there. It is likely that when the queens went out to fly they founded those colonies, so we believe it is likely that there are other colonies closer to that port but we have to go out and look for them,” he points out.
The red fire ant that is colonizing the world started from northern Argentina. From there it arrived in the United States a century ago, and little by little it has been spreading through Taiwan, China, the Caribbean, Australia and New Zealand: “In New Zealand they have managed to eradicate it three times, the last time was in 2009, when it was detected. a single mature nest, with thousands of workers. They drew a 2 km radius around it and it took them 3 years to eradicate a single nest, baiting it with poison.. “It is the only place where they have achieved it because they have great control of their customs.”
In addition to the indirect damage to biodiversity caused by the use of poison intended to kill the red ant, this species causes serious direct damage to ecosystems: “It is very aggressive, it stings a lot and displaces other ants, it has even swept away the Argentine ant, which we thought was impossible to move,” says. “We are concerned because it also affects vertebrates. Just as it stings people, it stings animals. It is a problem for ground-nesting birds, such as partridges, because they eat the chicks.. In South America, since they live in flood-prone areas with caimans, they even eat the caiman babies.. And it has been shown that they were capable of eating fawns, which are quite helpless at birth and take a long time to stand up.. If you are unlucky enough that there is an ant nest nearby, they can cover it, chop it and eat it because they really like to cut up meat,” he reviews.
Various ants in Sicily
Could it have been installed in Spain and not been detected? “The possibility exists but most likely it is not yet. What happens, and that's where the alarm comes from, is that it is capable of expanding very quickly due to human action and the wind.. In China it was discovered that it had established itself in 2004 and in 20 years it has colonized the entire south of the country, which is very large.”. In Spain, he adds, “there is no specific prevention plan because it has not been detected yet, but what is very important and is more or less done is the monitoring of all the products that arrive, and any invasive species is reported. to be detected, to act and put resources in place quickly because then it cannot be eradicated, only controlled, and that means spending money year after year, like the tiger mosquito or the Asian wasp,” says the leader of the study in which they have also Pompeu Fabra University and the Center for Ecological Research and Forest Applications (CREAF) participated, and it has received funding from the La Caixa Foundation.
Just last week, a comprehensive report from the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) estimated the global economic cost of the approximately 37,000 invasive alien species that are causing problems around the world at $423 billion annually.