Monday, December 10, 2007 - 9:41 AM

When trouble comes a knock’n: Why the “capadoccian ants” Stenamma alas and S. expolitum close the door

Michael G. Branstetter,, University of California, Davis, Entomology, One Shields Ave, Davis, CA, Manuel Solís Vargas,, Instituto Nacional de Biodiversidad, Entomología, P.O. Box 22-3100, Santo Domingo, Heredia, Costa Rica, and John T. Longino,, The Evergreen State College, 2700 Evergreen Parkway, Olympia, WA.

The “capadoccian ants” Stenamma alas and S. expolitum are two Neotropical ants with a remarkable suite of behaviors that is unprecedented among ants. Both species nest in clay banks, construct architecturally complex nests, maintain multiple unconnected nests per colony, and use a small “door pebble” to close the nest entrance when disturbed. Previous work hypothesized that these behaviors are adaptations to avoid army ant predation. We investigated the door closing behavior to determine the species specificity of the response and its proximate causes. By performing a series of presentation trials, we discovered that door closure is a chemically mediated response to ant predation generally and that the percentage of positive responses varies greatly among ant species. The significance of these results is discussed in the context of chemical communication and competition among ants.

Species 1: Hymenoptera Formicidae Stenamma alas (capadoccian ant)
Species 2: Hymenoptera Formicidae Stenamma expolitum (capadoccian ant)