A new trait in a well-studied ant: low aggression between workers from Lasius niger (Hymenoptera, Formicidae) nest complexes

Abstract

The formicine ant Lasius niger is one of the most abundant and most intensively studied Palaearctic ant species and was believed so far to form exclusively monogynous colonies, to spread via single-queen dispersal and to found claustrally. Two closely neighboring nest complexes of Lasius niger were observed in an abandoned field near Kyiv / Ukraine in 2017-2020. Nest complex A includes 14650 mounds on an area of 11.8 ha and nest complex B 15600 mounds on 13.3 ha. The nests within the nest complexes are connected via a developed trail network. Aggression tests revealed a low level of aggression between workers from different zones of the same nest complex but increased aggression in confrontations of nest complex workers with workers from a remote monodomous population. Reduced aggression between workers facilitate the integrity of the nest complex and its rapid growth.