Social immunity in a supercolonial invasive ant: Nest structure confers immune function

Area of Science:

• Ecology
• Behavioral Ecology
• Social Insects

Background:

• Group living in animals increases pathogen exposure.
• Social immune behaviors in kin groups, especially eusocial insects, mitigate these costs.
• Organizational immunity within nests modifies interactions to protect the colony core.

Purpose of the Study:

• Investigate how nest structure influences social immunity in the tawny crazy ant (Nylanderia fulva).
• Examine the interaction between Nylanderia fulva and its specialist pathogen, Myrmecomorba nylanderiae.
• Determine the role of nest architecture in preventing disease transmission.

Main Methods:

• Manipulated nest structure to assess its impact on social immunity.
• Confirmed spatial and behavioral segregation of workers in ant nests.
• Tracked the movement of infected and uninfected ants within different nest structures.

Main Results:

• A multi-chambered nest was required to prevent pathogen transmission to the colony core.
• Simplified nest structures resulted in complete disease transmission and loss of social immune function.
• Infected ants moved to the colony periphery, and uninfected ants could detect infection status.
• Infected ants shifted tasks, prioritizing corpse removal over foraging and brood care.

Conclusions:

• Nest structure is a critical determinant of social immune efficacy in ants.
• Spatial segregation within nests is a key mechanism for organizational immunity.
• Social immune behaviors against this specialist pathogen are conserved and generalized, similar to responses against generalist fungi.