Two ants of the species Temnothorax nylanderi: The lighter colored ant is infected with larvae of the tapeworm Anomotaenia brevis (bottom right) and thus has a different cuticle color as well as, more importantly, a considerably longer lifespan.
Photo: © Susanne Foitzik
A beautiful example of how the mindless, undirected process of evolution can produce parasites that turn their hosts into zombies, because that suits the survival interests of their offspring, was published a couple of years ago in Royal Society Open Science.
And more bad news for creationists because it makes their beloved designer god look even more malevolent.
The study was conducted by a team of researchers led by Professor Susanne Foitzik of Johannes Gutenberg University Mainz (JGU).
Why an intelligent designer would design something like this is something for creationists to explain because the designer of such a system can only be described as malevolent and planning to increase the suffering in the world, or full of hate for the ants it supposedly also designed.
The study showed that worker ants of the species Temnothorax nylanderi can live several times longer than normal workers of the same species when infected by a parasitic tapeworm, Anomotaenia brevis.
The ants are the intermediate hosts of the tapeworm, the primary host of which is a woodpecker. The longer an infected ant lives, the greater its chances of being eaten by a woodpecker, so it is in the interests of the tapeworm genes to keep the ant alive as long as possible.
The research is explained in a press release from JGU:
Parasites as fountains of youth: Study finds infected ants live much longer.
Life expectancy of tapeworm-infected worker ants is significantly higher than that of their uninfected nest-mates and resembles that of ant queens.
Ant workers that are infected with a tapeworm live much longer than their uninfected nest-mates. Parasitic infections are usually harmful to their hosts, but there are some exceptions. According to the results of a multi-year scientific study, ants of the species Temnothorax nylanderi show exceptionally high survival rates when infected with a tapeworm. "The lifespan of the infected ants is significantly prolonged. According to our observations, such workers have a survival rate similar to that of queens," said Professor Susanne Foitzik of Johannes Gutenberg University Mainz (JGU), leader of the study. Queens of this species can live for up to 20 years, while female workers rarely reach the age of two. Among possible explanations for this extended lifespan are the change in the physiology of infected ants caused by the parasites and the fact that infected workers are better supplied with food.
Social care in the nest linked to longer life.
In the case of ants, there is a stark divergence in lifespan between female castes. Many ant queens can survive for several decades. They spend almost all their lives safely in the nest where they are cared for by the workers, their daughters. In contrast, ant workers live for only a few weeks or months or, in rare cases, a few years. The infertile workers carry out all tasks in the nest, starting in brood care and progressing to riskier activities outside the colony as they grow older, such as foraging for food. The high life expectancy of queens is due to their low mortality rate, which is attributable to the high levels of social care they receive, their safe environment, and the activation of physiological repair mechanisms.
These factors may also contribute to the extremely high survival rates of Temnothorax-nylanderi workers infected with a tapeworm. This species of ant is common in Central Europe and forms small colonies on the forest floor, inside acorns or wooden branches. The insects are relatively small, with a body length of just two to three millimeters. They serve as an intermediate host for the tapeworm Anomotaenia brevis, whereby a single ant can be infected by up to 70 parasitic larvae. The parasites survive in the hemolymph, the body fluid of insects. Their complex life cycle is completed once they have been ingested by a woodpecker that feeds on the ants.
The research team led by Professor Susanne Foitzik looked at the long-term consequences of the parasitic infection by collecting ant colonies from forests around Mainz and observing them in the laboratory.
Infected workers differ in appearance, behavior, and physiologyWe tracked the survival rate of the workers and queens in both infected and uninfected ant colonies over three years, until more than 95 percent of the uninfected workers had died. [At that point, over half of the infected workers were still alive – exhibiting a survival rate practically identical to that of the long-lived queens.]
It is quite extraordinary that a parasite can trigger such a positive change in its host. This lifespan extension is very unusual.
Professor Susanne Foitzik, project leader
Institute of Organismic and Molecular Evolution
Johannes Gutenberg University, Mainz, Germany>
The infected ants are easily distinguished from their brown nest-mates due to their lighter, yellow color, an effect that results from their cuticle being less pigmented. They are also less active and receive enhanced care from other workers in the nest.
The tests also revealed that infected ants have metabolic rates and lipid levels similar to those of younger ants. It would seem that these ants remain in a permanent juvenile stage as a result of the infection. This is likely down to both the tapeworm larvae altering the expression of ant genes that affect aging and to the parasites' release of proteins containing antioxidants into the ants' hemolymph.The infected insects get more attention and are fed, cleaned, and looked after better. They even benefit from slightly more care than the nest's queen.
The infected insects live a life of luxury, but the fact that they receive more social care cannot alone account for their prolonged lifespan.
Professor Susanne Foitzik.
Even though the mystery of their long life has not yet been fully resolved, the behavior of the infected ants themselves does not seem to be the decisive factor. The research team, which included scientists from the Max Planck Institute for Biology of Ageing and Tel Aviv University, found no evidence that the insects actively beg for better care. However, chemical signals on the cuticle of infected ants were found to elicit more attention of their nest-mates. The scientists will undertake further research in order to identify the factors, particularly on the molecular and epigenetic level, behind the infected workers death-defying attributes.
Technical details of the study can be found in the published paper:
AbstractThe usual invitation then to creationists to explain why this is not an example of design, the designer of which can only be described as malevolent, or why they would prefer us to think of their designer god as a malevolent force, seeking to increase suffering in the world, than have us believe this sort of thing can come from a mindless, undirected natural process.
Social insects are hosts of diverse parasites, but the influence of these parasites on phenotypic host traits is not yet well understood. Here, we tracked the survival of tapeworm-infected ant workers, their uninfected nest-mates and of ants from unparasitized colonies. Our multi-year study on the ant Temnothorax nylanderi, the intermediate host of the tapeworm Anomotaenia brevis, revealed a prolonged lifespan of infected workers compared with their uninfected peers. Intriguingly, their survival over 3 years did not differ from those of (uninfected) queens, whose lifespan can reach two decades. By contrast, uninfected workers from parasitized colonies suffered from increased mortality compared with uninfected workers from unparasitized colonies. Infected workers exhibited a metabolic rate and lipid content similar to young workers in this species, and they received more social care than uninfected workers and queens in their colonies. This increased attention could be mediated by their deviant chemical profile, which we determined to elicit more interest from uninfected nest-mates in a separate experiment. In conclusion, our study demonstrates an extreme lifespan extension in a social host following tapeworm infection, which appears to enable host workers to retain traits typical for young workers.
Beros, Sara; Lenhart, Anna; Scharf, Inon; Negroni, Matteo Antoine; Menzel, Florian; and Foitzik, Susanne. (2021)
Extreme lifespan extension in tapeworm-infected ant workers
R. Soc. open sci. 8202118202118. DOI: 10.1098/rsos.202118
Copyright: © 2023 The authors.
Published by The Royal Society. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
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