Meeting Abstract
Social insect colonies are regulated as non-hierarchical, distributed systems in which ants must make individual decisions that are informed by local information cues. Changes in colony behavior occur collectively because of the many decisions of individuals. We report how brain monoamines affect the decisions of individual ants after detecting chemical cues during interactions with nestmate ants, fighting with non-nestmate ants, or exposure to nestmate and non-nestmate chemical cues during the self-organization of warfare by pavement ant (Tetramorium caespitum) colonies. Wars are hostile conflicts in which members of one society coordinate their efforts to kill or injure members or disrupt the normal functioning of another. The pavement ant is a tramp species well known for its ant wars in which thousands of workers from two colonies fight. Fighting is ritualized; ants fight by grabbing another ant’s mandibles with its own and pairs undergo what can be described as a “push-of-war” while other ants recruit more workers to the battle and few, if any, ants die during the battle. What are the rules that influence the collective-organization of these “wars” and how are cooperative and agonistic behaviors modulated in individuals by brain monoamines? We report that serotonin (5-HT) levels were higher in ant brains after interactions with nestmate ants or their chemical cues. Dopamine levels were elevated only after interactions with live nestmate or non-nestmate ants. Brain octopamine levels were elevated in ants that fought non-nestmates. Increasing octopamine levels increased the probability that an ant will fight a non-nestmate ant.
