Meeting Abstract
Ant colonies are distributed systems that are regulated in a non-hierarchical manner. Without a central authority, individuals inform their behavioral decisions by comparing information in local cues to a set of inherent behavioral rules. Collectively, many individual behavioral decisions lead to changes in colony behavior including the decision to be aggressive with neighboring colonies. Pavement ants (Tetramorium caespitum ) form conspicuous wars with neighboring colonies in which thousands of ants participate. Wars last for many hours and few workers die in the process as because fighting is ritualized. A worker is likely to decide to fight if 1) it has had a recent history of interactions with nestmates and 2) detects a mismatch in nestmate recognition cues, coded in cuticular hydrocarbon profiles, on the cuticle of a non-nestmate ant. We present evidence showing how tactile and chemical cues and social context – isolation, nestmate interaction, or fighting non-nestmates – affect levels of the brain monoamines serotonin (5-HT), octopamine (OA), and dopamine (DA) in pavement ant brains. Interactions with nestmate ants prior to meeting a non-nestmate opponent elevate 5-HT and octopamine levels in a worker’s brain. Levels of 5-HT and octopamine above a threshold when an ant detects non-nestmate chemical cues, it is likely to fight the opponent. Dopamine levels are elevated during fighting. We have additional evidence that 5-HT and OA also play a role in the assessment of food quality.
