Social insects like ants face heightened pathogen exposure due to dense colonies and varied worker roles. We examined immune activity in Myrmica scabrinodis ant workers infected with the non-lethal fungus Rickia wasmannii. Infection by R. wasmannii altered the ant workers’ immune response, notably elevating levels of active phenoloxidase (PO) compared to uninfected counterparts. Interestingly, while age affected total PO levels (reflecting both active and inactive forms), it didn’t influence infection impact.
Contrary to the typical age-related decline in immune function observed in many species, our study suggests increased immune activity in older ant workers exposed to long-term fungal infection. This phenomenon underscores the complex interplay between age, pathogen pressure, and immune response in social insect populations, offering insights into the consequences of prolonged parasitic interaction on individual immune profiles.