The Tapinoma Magnum, a “very invasive ant that makes everyday life difficult”

In recent years, ants of a new type have ruined the lives of around 200 houses in a district of the city of Saumur (Maine-et-Loire). This invasive alien species, called Tapinoma Magnum, will also proliferate this summer, thanks to the high temperatures. Who are these insects and can we overcome them? The point with a specialist, Loïc Bidault, elected in ecology, sustainable development and energy transition at the city of Saumur who also holds the position of vice president of the Conservatory of natural spaces of the Pays-de-la-Loire.

Loïc Bidault, elected to ecology in the city of Saumur and vice-president of the Conservatory of natural spaces of the Pays-de-la-Loire. – Loic Bidault

You can show us the Tapinoma Magmo ?

It is a Mediterranean species, more precisely Corsican, which then arrived in the south of France. He is now with us, in Saumur, for three to six years, but we really identified him last year, following the protests of the inhabitants and with the help of scientists from the Research Institute on Insect Biology (Irbi) of Tours. It is thought to have arrived through the transport of ornamental plants, often surrounded by clods of earth, perhaps in the fashion of olive trees or palm trees that come from all over the Mediterranean. Scientists also make the connection with global warming because they find environments with us that are welcoming. It is a species with a very particular behavior, very invasive, and which brings strong discomfort.

Meaning what ?

The ant Tapinoma Magnum lives in super colonies. They spread particularly quickly, without any competition with other anthills. We can recognize them with the naked eye because they are very small and have an extremely gregarious, hyperactive behavior. They are found mainly on degraded soils, cuttings. But they are also there in large numbers in the gardens: it swarms everywhere and if you go out, they climb on you. A lady told me that this is why her grandchildren no longer came to her house in the summer! They don’t bite but have a very invasive side. Another peculiarity, when they are crushed they give off a smell of rancid butter …

And they do damage too …

Yes, especially in the vegetable gardens, we have seen fully attached zucchini or young tree seedlings. Indeed, these species that do not have predators create a vacuum around them: in the areas where the Tapinoma Magnum thrives, our classic ant is in danger of disappearing in the next few years. Thanks to the pipes, the cables, they are also introduced into the houses… We had electric meters that jumped in some inhabitants! This makes daily life difficult for some of those affected. Last year it took on a considerable size, people were completely defenseless, so we had to come up with a scientific and structured approach, with a lot of education.

What can we do with these ants?

As soon as the species is identified, it must be treated immediately. What we couldn’t do fast enough here, with now an 18-hectare district in question, and the appearance of these ants in two cemeteries as well. Scientists tell us that we will not be able to eradicate it so we contain, we limit as much as possible. We have voted for financial aid in three years to carry out three treatments per year in the people concerned. As for public spaces, we treat every 15 days from March to September with a spinosad-based product that can be used organically. The results are quite positive.

The Tapinoma Magnum seems to be gaining ground in France, especially in the West …

Saumur acts as a laboratory for the whole of France and the municipalities regularly call me to ask how we are proceeding. It is therefore clear that we will talk about this ant again, here but also elsewhere, and in particular in the Loire Valley or in the Loire-Atlantique, where it has been identified for example in Ancenis. We will see how the species evolves, there may be some surprises. Near Pau, there is a village where the ant disappeared in one summer, for no reason … Fingers crossed what happens to us! There is also the possibility that another invasive species will come and move this one. Meanwhile, the drop in temperatures should offer us a period of calm, until March.

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