An experimental study of behavioral mechanisms of relationships between red wood ants and ground beetles

Abstract

Behavioral mechanisms regulating the competitive relations between the red wood ant Formica aquilonia and the ground beetles Carabus regalis, Pterostichus melanarius, P. magus, P. oblongopunctatus, Harpalus smaragdinus, and Amara nitida were studied by artificially initiated collisions between living insects as well as with the use of imitation models. Members of different functional groups within an ant family (aphid-milkers, hunters, and guards) behaved differently towards beetles. Active ants were shown to respond selectively to different features of the possible competitors, such as coloration, the presence of “appendages” (legs, antennae), body symmetry, rate of movement, and scent. Field and laboratory experiments demonstrated the ability of beetles to avoid collisions with active ants. The scent of anthill material attracted ground beetles, which consumed dead ants. The gained individual experience may allow the beetles to use supplementary forage resources in the territories controlled by ants. The flexible tactical patterns facilitate spatial segregation of ground beetles and ants in the same territory and result in a more complete utilization of food resources.