This is probably a question that children have already asked themselves.
How many ants are there on Earth?
An answer can now be provided: according to a new study published on Monday, there are at least 20 million billion ants on Earth.
A probably largely underestimated estimate of the world population of these insects, key to their ecosystem.
Ants play a significant role wherever they are present, serving both as a means of dispersal for plant seeds, as hosts for certain organisms and as predators or prey for other animals.
Determining their global population is therefore important in order to be able to measure the consequences that modifications to their habitat - including climate change - may have.
Some studies had already attempted a count based on an estimate of the overall insect population and had resulted in a much lower number of ants.
For this new attempt, published on Monday in the scientific journal Proceedings of the National Academy of Sciences (PNAS), the researchers analyzed the results of 465 studies having measured locally, in the field, the number of ants.
Large regions without data
These hundreds of studies have used two standardized techniques: the setting of traps capturing individuals passing by for a certain period of time, or the analysis of the number of ants present on a given plot of foliage on the ground.
The total biomass of ants on Earth (measured in dry matter) is thus estimated at 12 million tonnes.
This is more than the biomass of wild birds and mammals combined, and it is 20% of that of humans.
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While surveys have been carried out on all continents, some major regions presented very little or no data, particularly in Central Africa or Central Asia.
This is why "the true abundance of ants is probably considerably higher", warns the study.
“It is of the utmost importance that these gaps are filled, in order to provide a complete picture.
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There are more than 15,700 species or subspecies of ants, and probably as many not yet described, according to the study.
Amazingly, they are present everywhere on the planet.
But nearly two-thirds of ants are found in only two types of ecosystems: forests and tropical savannahs, conclude this work.
In the future, the researchers plan to study the environmental factors influencing the density of ant populations.