Published on : 05/17/2020 – 00:05Modified : 05/17/2020 – 02:05
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It was with it that it all started: the bat, which hosted the new coronavirus, before transmitting it to humans, directly or indirectly. A true reservoir of viruses, the bat is, however, also an ally of man.
Night is falling on the Bois de Vincennes in Paris. And we hear little clicks. These are ultrasound, which the human ear would be incapable of hearing, emitted by bats, and amplified by the case that Jean-François Julien, a professional chiropterologist, specialist in bats, connected to his smartphone, at the CNRS and the Museum of Natural History in Paris. The ultrasound of the bat also appears on its screen, in the form of spectra. After having “observed” a first pipistrelle (the most common species of bat in France), Jean-François Julien exclaims: ” Ah! Another species has arrived, the murine from Daubenton, which hunts flush with the water. “
The bat, the only mammal capable of flying, finds itself every night around a body of water, to drink there and to track insects. ” At night, they have much less competition from birds, explains Jean-François Julien. The darkness also shelters them from predators. It is to locate itself in space, and to locate its meal, that the bat uses ultrasound, which it emits and which it echoes in its large ears. This is the technique of echolocation. ” It cries ten times per second, but when it approaches an insect, it accelerates the rhythm of the calls which can go up to 200 calls per second, to have a maximum of information at the time of the capture. “
Bad reputation
A fleeting shadow has just passed. The wind rustles the branches of the trees. Night has just fallen, the bats are out. The setting for a horror film is set … A genre in itself, the film with bloodthirsty bats. The bat in the West has a bad reputation. ” Apparently, they are not very friendly, recognizes Jean-François Jullien. They also suffered from the confusion between the myth of vampires in Europe and the discovery in tropical America of species aptly nicknamed vampires, which feed on blood (but very exceptionally human blood). It didn’t help improve their reputation! “While in Asia, the bat brings good luck. Habitually. ” In China, notes Jean-François Julien, she is even supposed to treat asthma, which is a little paradoxical when we think that she passed on to us indirectly or directly a respiratory virus! “
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AIDS, Ebola, the first outbreak of SARS, and today SARS-Cov2… The bat has an impressive track record. One of the main reservoirs of viruses and zoonoses, diseases transmitted to humans by animals. Because of a mysterious immune system and an impressive diversity: the large family of bats counts 1,400 species, and we have just discovered four others in East Africa. Second animal order after rodents, the bat represents a quarter of all mammal species listed on the planet. ” The more species, the more risk there is of carrying a virus that can pass into humans, explains the chiropterologist. In the colonies, which can number several thousand individuals, bats form real swarms, they are touch-to-touch, which allows the virus to pass from one species to another, to diversify further. “
An animal useful to humans
It is also the same species of bat, the horseshoe bat, which is at the origin of the epidemic of Sras in 2003 and of the new coronavirus today, present in the Chinese province. from Yunnan. ” A region which has not undergone major upheavals “Says Jean-François Julien, who judges” abusive the shortcut that is made today between ecological disturbance and pandemic. For him, the development of transport is more responsible for the pandemic than the demographic pressure on ecosystems.
► Also listen: Bats, essential for the environment
Potentially dangerous, not an easy physique, the bat is nevertheless very useful for humans, first by hunting harmful insects. ” In the United States, we even calculated what it could bring or save to agriculture: between 4 and 50 billion dollars per year. The bat also plays a vital role in the regeneration of tropical forests, thanks to the seeds they disperse. Their droppings also make an excellent fertilizer, guano. It’s hard to believe in the days of the coronavirus, but the bat is also a friend of man.
The question of the week
“Can we kiss a tree without his consent?” “
Yes, for the tree we can, even if we don’t really know what he thinks about it … We call it silvotherapy, tree therapy, which was born in Japan. Hugging a tree, giving it a big hug, it soothes, it’s good for your health. Scientific studies have shown this. A patient with a view of nature is more likely to heal faster. In general, contact with nature, greenery, it feels good! Because that’s where we come from. The confined city dwellers realized this. And today doctors are demanding, in the name of mental health, the reopening of parks in Paris. Because city life in human history is very recent. The man descends from the monkey, and the monkey descends from the tree … So we hope this column will do you good every week!
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