Variability of immune gene expression among different groups within ant colonies shows a multifaceted response to infection by a non-lethal ectoparasitic fungus
Variability of immune gene expression among different groups within ant colonies shows a multifaceted response to infection by a non-lethal ectoparasitic fungus
Orban-Bakk, K.; Schultner, E.; Heinze, J.; Marko, B.; Csata, E.
AbstractSocial insect colonies are known to be targeted by a wide variety of different parasites and pathogens because of their high host abundance. However, within a colony, the level of risk to exposure could vary among individuals depending on their role. Unlike many known parasites, which mostly target specific groups of individuals, e.g. foragers, the myrmecoparasitic fungus Rickia wasmannii infects entire ant colonies, being linked to subtle changes in physiology, morphology and behaviour. We investigated how different groups within the colonies respond to being exposed to the fungus by measuring the expression of the genes defensin 1 and prophenoloxidase, both vital components of ant immunity. We found that workers, queens and broods varied in their immune response. Workers displayed diverse profiles, with variable responses to infection: in same-age workers, both prophenoloxidase and defensin 1 levels exhibited increases in correlation with pathogen loads. Queens exhibited a more pronounced immune response. Highly infected queens had a heightened immune response. Larvae did not show a discernible response. Morphological and physiological characteristics had limited effects on gene expression, except in the case of queens, where larger individuals displayed higher defensin 1 expression. Our study shows that these divergent responses likely stem from the differing physiological needs and priorities of various groups within the colony.