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Published on: October 12, 2018
Non-lethal fungal infection could reduce aggression towards strangers in ants
Enikő Csata1,2, Luca Pietro Casacci3, Joachim Ruther4
1Institute for Zoology, University of Regensburg, Universitätsstraße 31, D-93040, Regensburg, Germany. Eniko.Csata@biologie.uni-regensburg.de.
Abstract:
Many parasites interfere with the behaviour of their hosts. In social animals, such as ants, parasitic interference can cause changes on the level of the individual and also on the level of the society. The ant-parasitic fungus Rickia wasmannii influences the behaviour of Myrmica ants by expanding the host's nestmate recognition template, thereby increasing the chance of the colony accepting infected non-nestmates. Infected ants consistently show an increase of the alkane tricosane (n-C23) in their cuticular hydrocarbon profiles. Although experimental application of single compounds often elicits aggression towards manipulated ants, we hypothesized that the increase of n-C23 might underlie the facilitated acceptance of infected non-nestmates. To test this, we mimicked fungal infection in M. scabrinodis by applying synthetic n-C23 to fresh ant corpses and observed the reaction of infected and uninfected workers to control and manipulated corpses. Infected ants appeared to be more peaceful towards infected but not uninfected non-nestmates. Adding n-C23 to uninfected corpses resulted in reduced aggression in uninfected ants. This supports the hypothesis that n-C23 acts as a 'pacifying' signal. Our study indicates that parasitic interference with the nestmate discrimination of host ants might eventually change colony structure by increasing genetic heterogeneity in infected colonies.
Insights
Parasitic fungus Rickia wasmannii alters ant behavior by increasing cuticular hydrocarbon n-C23. This chemical signal reduces aggression, facilitating acceptance of infected non-nestmates and potentially altering colony structure.
Area of Science:
- Behavioral ecology
- Chemical ecology
- Myrmecology
Background:
- Parasites often manipulate host behavior to enhance transmission.
- Social insects like ants are susceptible to parasitic manipulation, affecting both individuals and colony dynamics.
- The fungus Rickia wasmannii infects Myrmica ants, altering their nestmate recognition.
Purpose of the Study:
- To investigate the role of the cuticular hydrocarbon tricosane (n-C23) in mediating the acceptance of infected ants.
- To test the hypothesis that increased n-C23 on infected ants acts as a pacifying signal.
- To understand how parasitic manipulation of social behavior impacts colony structure.
Main Methods:
- Experimental application of synthetic n-C23 to ant corpses.
- Observation of aggression levels of infected and uninfected Myrmica scabrinodis workers towards control and manipulated corpses.
- Analysis of cuticular hydrocarbon profiles in infected ants.
Main Results:
- Infected ants showed reduced aggression towards infected non-nestmates.
- Application of n-C23 to uninfected corpses decreased aggression from uninfected workers.
- The cuticular hydrocarbon n-C23 appears to function as a 'pacifying' signal in Myrmica ants.
Conclusions:
- Increased n-C23 is a key mechanism by which Rickia wasmannii facilitates the acceptance of infected individuals.
- Parasite-induced changes in chemical communication can alter social interactions and potentially increase genetic diversity within ant colonies.
- This study highlights the sophisticated manipulation strategies employed by parasites in social systems.
