Spatiotemporal evolution of the trail network in Lasius fuliginosus (Hymenoptera, Formicidae).

In Lasius fuliginosus, the existence of a permanent trail system, stable during a season and practically unchanged from one year to the next, was confirmed. These trails radiate from the nest and lead the foragers to trees and shrubs colonized by aphids where they collect honeydew. These aphid sites are also stable during a season and from one year to the next. Other kinds of trails were observed: temporary honeydew collecting trails, temporary hunting trails and ephemeral recruitment trails. These trails, always connected to permanent trails, lead foragers respectively to temporarily exploited aphid sites, to large areas explored by ants and to large prey. Unlike permanent trails, they have a short life-time (several weeks for the temporary trails, some hours for the ephemeral trails) and they are not found in the same position from one year to the next. The temporarily exploited aphid sites are each year new ones originating, at least for a part of them, from the colonization of new sites by winged migrating aphids. They are thus spatially and temporally unpredictable food sources, like prey.