World is home to at least 20 trillion ants, study finds
Determining how many ants inhabit the globe is important in order to be able to measure the consequences that changes in their habitat can have.
At least 20 million billion ants exist on Earth, according to a new study providing a probably still largely underestimated estimate of the world population of these insects, key to their ecosystem.
Determining how many ants inhabit the globe is important in order to be able to measure the consequences that changes to their habitat – including climate change – may cause.
Ants play a significant role wherever they are present, serving both as a means of dispersal for plant seeds, as a host for certain organisms and even as predators or prey for other animals.
Some studies had already attempted a count starting from an estimate of the overall population of insects and had ended up with a number of ants much lower.
Solenopsis richteri on a leaf.
For this new attempt, published Monday in the journal scientific Proceedings of the National Academy of Sciences (PNAS), the researchers analyzed the results of 465 studies that measured locally, in the field, the number of ants.
These hundreds of studies have used two standardized techniques: setting traps that capture passing individuals for a certain period of time, or analyzing the number of ants present on a given plot of foliage on the ground.
Ants (Linepithema humile) move across a bridge.
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 20% of that of humans.
While surveys have been carried out on all continents, some large regions presented very little or no data, especially in Central Africa or Central Asia.
This is why the true abundance of ants is likely considerably higher, the study warns. It is of the utmost importance that these gaps be filled, in order to provide a complete picture.
Ants Nylanderia fulva devour a spider.
There are more than 15,700 species or subspecies of ants, and probably as many yet to be described, according to the study. Amazingly, they are found everywhere on the planet.
But nearly two-thirds of ants are found in just two types of ecosystems: tropical forests and savannahs, conclude this work.
In the future, the researchers plan to study the environmental factors influencing the density of ant populations.