Trail Patterns and Movement of Workers Among Nests in the Ant Formica Obscuripes (Hymenoptera: Formicidae)

In ants of the genus Formica, intraspecific interactions among workers from different nest mounds vary from mutual tolerance to aggression and territoriality. For example, workers of Formica opaciventris and F. ulkei commonly visited nearby nests without evoking agonistic responses (Scherba, 1964; Talbot, 1961). On the other hand, in a study of a British population of F. rufa, workers engaged in aggressive territorial contests with workers from nearby mounds (Skinner, 1980). Both aggressive and non-aggressive interactions have been observed within populations of F. rufa in Russia (Marikovsky, 1962) and F. polyctena (Mabelis, 1979a, b). This is not surprising, since Formica populations may consist of separate colonies, some of which have multiple nests (i.e. polydomous colonies; Pamilo et al., 1978; Wilson, 1971). The elucidation of patterns of interactions among workers from different nest mounds is essential for an understanding of the genetic organization of populations (Pamilo, 1981, 1982; Pamilo et al., 1978), the social structure and spatial dispersion of colonies, and the proximate factors influencing the form of intraspecific interactions among ants. Such interactions are apparently influenced by the recent history of nest founding and