Defensive behavior is linked to altered surface chemistry following infection in a termite society
Résumé
The care-kill response determines whether a sick individual will be treated or eliminated from an insect society, but little is known about the underpinnings of this process. We exploited the stepwise infection dynamics of an entomopathogenic fungus in a termite to explore how care-kill transitions occur, and identify the chemical cues behind these shifts. We found collective responses towards pathogen-injected individuals to vary according to severity and timing of pathogen challenge, with elimination (via cannibalism) occurring sooner in response to a severe active infection. However, injection with inactivated fungal blastospores also resulted in increased albeit delayed cannibalism, even though injection did not universally cause host death. This indicates that the decision to eliminate an individual is triggered before pathogen viability or even terminal disease status is known. We then compared the surface chemistry of differently challenged individuals, finding increased amounts of long-chained methyl-branched alkanes with similar branching patterns in individuals injected with both dead or viable fungal blastospores, with the latter showing the largest increase. This coincided with the highest amounts of observed cannibalism as well as signs of severe moribundity. Our study provides new mechanistic insight into the emergent collective behaviours involved in the disease defence of a termite society.
Domaines
Biodiversité et Ecologie| Origine | Fichiers produits par l'(les) auteur(s) |
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