Gironde is experimenting with the reintroduction of insects that had disappeared for 60 years

The dung beetle disappeared in the 1960s from the Cousseau pond nature reserve, in Gironde. After a first wave in 2023, new beetles were released at the beginning of May.

It’s a unique experience in France. In front of the lenses of around ten cameras, Cyril Forchelet, scientific manager of the reserve, is preparing to release the dung beetles, locked in a wooden box: “Like the boxes we use for big cats when we reintroduce them. Obviously, ours are much less ferocious.” They are even a little lazy when opening the miniature cage. “They don’t have much motivationnotes Cyril Forchelet. I think the weather makes it a little difficult for them to get out. We’re going to put them directly on the dung and scatter them directly on the clearing.”

Eighty of these Scarabaeus laticollis – their scientific name – are thus released, 60 years after the disappearance of the species due to dewormers administered to livestock. “The dung actually becomes sterile, and the dung beetle cannot find its way there because it cannot lay eggs in the dung. So obviously, it is not an environment that suits it”explains the scientific manager of the reserve.

A complement more than a solution

From now on, the cows in the reserve are no longer treated: the beetles should be able to play their role by recycling the dung, and flourish. But to be sure, it will take time. “This is the first reintroduction of insects in Franceindicates Cyril Forchelet. We wipe off the casts a little. We will probably only have the first results in a few years, to say whether it worked or not.”

The only indication for the moment: of the sixty dung beetles already released in 2023, some are still there, identified thanks to the small marks written on their shell. The results will in all cases be closely monitored by entomologists, including Julien Touroult from the National Museum of Natural History, who is very interested in this extremely rare attempt. “I found a scientific publication that lists 74 experiences around the world. These were considered positive in 52% of cases”he explains.

But the scientist warns, these reintroductions will not be enough to stop the collapse of insect populations: “In France, we have 40,000 species of insects. Let’s say that 10% of them are threatened with extinction. We will never have the means to treat all the threatened species one by one through reintroductions. So this is not the solution at all.” But only a complement to actions already known: reducing pesticides, pollution and land artificialization.