Meeting Abstract

49.2  Saturday, Jan. 5  The organization of “wars” by pavement ants GREENE, MJ; University of Colorado Denver michael.greene@ucdenver.edu

The pavement ant (Tetramorium caespitum) is a tramp species commonly associated with human habitation in northern temperate regions. The species is well known for its ant “wars” in which thousands of workers from two colonies fight in a large group. Fighting appears to be ritualized; ants engage in fights 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. Few ants die during the battle. What are the rules that influence organization of these “wars”? I report that workers discriminate nestmates and non-nestmates by detecting cues coded in the mixture of cuticular hydrocarbons on the cuticle of ants they antennate. Nestmate recognition cues are coded in the relative abundance of methyl-alkane and alkene hydrocarbons. However, detection of cues on the cuticle of non-nestmate ants is not sufficient to stimulate fighting. Patterns of recent interactions with nestmate ants and the size of the group of ants fighting influence an ant’s decision to fight. Workers respond to interactions with heterospecific ants using a different set of rules that do not depend on group size.