Many of us think of eternal youth as one of those wishes that we would like to launch or ask for and have it fulfilled. But, as in the stories with the genie in the lamp, there is always a catch . Scientists have discovered a similar version of this story that takes place in ant nests where the guarantors of eternal youth are parasites that dramatically extend the lifespan of worker ants (but at what cost).
Did you know that worker ants only live for a few weeks or months, and in rare cases, a few years? Queens can survive for several decades. They spend most of their lives safely in the nest where they are cared for by the workers. The high life expectancy of queens is due to their low mortality rate, attributable to the high levels of social care they receive, their safe environment and the activation of physiological mechanisms of repair. Unless a parasite with special gifts appears.
The ‘elixir of eternal youth’
A team of researchers from Johannes Gutenberg University in Mainz, Germany, observed 58 colonies of Temnothorax ants over three years, some infected with Anomotaenia brevis and others without it, and inspected them every 10 days. The parasite, the tapeworm Anomotaenia brevis, is capable of extending the life span of a Temnothorax nylanderi ant by up to a decade or two, approaching the age of a queen ant. These parasites survive in hemolymph, the body fluid of insects.
By the end of the experiment, all the original uninfected worker ants had died, but in the colonies where Anomotaenia brevis had made an appearance, half of the infected queens and workers were still alive.
“It is quite extraordinary that a parasite can trigger such a positive change in its host. This extension of the lifespan is very unusual,” explains evolutionary biologist Susanne Foitzik, co-author of the work.
The parasite-laden ants – they could hold up to 70 tapeworms inside them – didn’t just outlive their sisters, the team found. They were pampered in the process. They spent their days resting in their nest, not performing any of the tasks expected of the workers. They were fed and carried by their sisters, often receiving more attention than even the queen, something unheard of in a typical ant society. Without giving the others absolutely nothing in return.
What is hidden under this apparent perfection?
Uninfected ants in parasitized colonies, the researchers observed, were working much harder and neglecting even caring for their queen. They died sooner than they could have if the colonies had remained parasite-free. In addition, they showed signs of stress.
And the “gift” was not altruistic either: apart from keeping them young and healthy longer, it also makes them more lazy and docile so that their host in question does not escape when a woodpecker approaches the colony . It is all part of a more ambitious plan. Their complex life cycle is complete once they have been ingested by a woodpecker that feeds on ants. Thus, the end of the game is that these parasites reproduce within the entrails of the bird. These then defecate the tapeworm eggs, where the foraging ants will stumble upon them and feed them to their young in the nest, starting the cycle of life anew.
Referencia: Sara Beros, Anna Lenhart, Inon Scharf, Matteo Antoine Negroni, Florian Menzel, Susanne Foitzik. Extreme lifespan extension in tapeworm-infected ant workers. Royal Society Open Science, 2021; 8 (5): 202118 DOI: 10.1098/rsos.202118
