2024-01-25 19:00:06
No one would say it but a tiny, big-headed ant is challenging the king of the jungle himself. This is the ant lion (Pheidole megacephala), a voracious invasive species that is altering the vegetation cover of the African savannah, making it difficult for lions to hunt zebras, their favorite prey.
Despite its harmless appearance, this ant is included in the ranking of the 100 most harmful invasive alien species in the world, a list prepared by the International Union for Conservation of Nature (IUCN). So it is already registered by scientists who monitor the havoc caused by the arrival of these voracious species in areas where they did not previously live, as is the case of East Africa.
As ecologist Todd Palmer, professor of Biology at the University of Florida and author of this research, recalls, about 15 years ago they began to detect the impacts of the ant lion, known in English as the big-headed ant, although it had already been colonizing new ones for some time. territories: “Previously, none of us were aware of their presence because They are not aggressive towards large animals, including people. Now we see that they are transforming landscapes in very subtle ways but with devastating effects,” he warns.
The study that this Thursday reveals in Science magazine how it is complicating the life of Africa’s most emblematic hunter is the result of three decades of observations and a good example of how complex and fragile an ecosystem is, as it illustrates the network of interactions that There are ants, trees, lions, zebras, buffalos and elephants. “These small invaders are pulling at the ties that bind an African ecosystem, determining who gets eaten and where,” Palmer says.
Dos leonesTodd Palmer
To carry out the research, they combined in situ observations with technologies such as camera traps, collars placed on the lions to follow their steps via satellite, or statistical models. Thus, the researchers discovered that the invasion of big-headed ants in the Ol Pejeta Conservancy, a wildlife area located in central Kenya, has indirectly made lions less effective at killing zebras, their main prey.
This is because these invasive insects kill the native ants that protect the acacias, preventing their leaves from being devoured by elephants and other herbivores that live in that region, a protective role that has been known since the beginning of the century: “For our surprise, we discovered that These small ants act as effective defenders of the trees, stabilize the tree cover of these landscapes and make it possible for acacias to survive in an area where large herbivorous mammals live,” says Palmer.
Comparison of acacias invaded by this ant species and those not affected Todd Palmer
But the arrival of the big-headed ant upset that balance. Without the protection of native ants, whose colonies are devoured by the invasive species, elephants and other animals have no obstacles to eating the leaves of these trees, that little by little they become naked or semi-naked. With less tree cover to hide in, lions have a harder time ambushing zebras.
The lions, which are the kings of the jungle for a reason, are adapting to the new situation and according to Palmer, They begin to pay more attention to African buffaloes faced with the difficulties of hunting zebras.
Thus, the scientists determined that the killing of zebras in places where the big-headed ant had not reached was 2.87 times higher than in places invaded by this invasive species. From 2003 to 2020, the proportion of zebras killed by lions fell from 67% to 42%, while the proportion of buffalo killed rose from 0% to 42%.
“They are transforming landscapes in very subtle ways but with devastating effects”
Therefore, the good news is that since the invasion of the big-headed ant was detected, the lion population has not been reduced, at least for the moment, according to the authors.
“Nature is intelligent and creatures like lions tend to find solutions to the problems they face, But we still do not know what could result from this profound change in the lions’ hunting strategy. We are very interested in following this story,” admits the ecologist.
The African savannah is not the only ecosystem that the big-headed ant is altering, since according to Palmer, it has already spread to many places: “They are everywhere, especially in tropical and subtropical areas. “You can find them in your yard in Florida, and it’s people who move them from one place to another.”
An elephant walks through a landscape invaded by the ant lion Brandon Hays
The ant lion is a pest of some crops of coffee, cocoa and fruit trees, but at the same time it is used to control some pests that affect other crops or the expansion of some species of tick that affects livestock.
According to Palmer, they are working with land managers to investigate interventions, including temporary fencing of large herbivores to minimize the impact of invasive ants on tree populations.”
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