Exposure to non-nestmate odors changes the odorant receptor profile in Acromyrmex echinatior leaf-cutting ants

Social insects recognize their nestmates by colony-specific olfactory labels stored as neural templates in the memory. The template is often considered a product of learning in higher brain centers. However, some evidence suggests that the template may be stored in the neural periphery, i.e., the antennae or antennal lobes. We investigated a potential mechanism for peripheral nestmate recognition templates: the composition and plasticity of the antennal odorant receptor (OR) profile. We found that OR gene expression in leaf-cutting ants is colony-specific, mirroring the colony-specific recognition labels. After exposure to non-nestmate odors, the ants exhibited reduced aggression toward the non-nestmate label, indicating habituation. When we exposed two different colonies to the same non-nestmate odor, their OR profiles converged. These results suggest that the olfactory system can adapt to the current nest-specific olfactory environment and may explain how habituation plays a role in nestmate recognition.