SPATIAL SPECIALIZATION OF THE FORAGERS AND FORAGING STRATEGY IN LASIUS-FULIGINOSUS (LATREILLE) (HYMENOPTERA, FORMICIDAE)

The spatial specialization in Lasius fuliginosus was investigated in t he field by a mass-marking of foragers with colors. In the spring, sum mer and autumn, foragers exhibit a high degree of persistence, with co efficients of fidelity between 83 and 96%, in using a particular forag ing trail, in visiting a particular tree or shrub housing aphid coloni es, and even micro-sites like a particular branch. A high degree of fi delity to particular temporary hunting ground areas has also been show n. Trail and aphid site fidelity persist for at least 1 to 3 months an d are preserved through the hibernation period (about 5 months). Howev er, in early spring, a period during which food sources are scarce, tr ail fidelity is lower (coefficient of fidelity: 57%). Spatial speciali zation develops quickly in foragers recruited to a new permanent food source. Once acquired, the specialization is not rigid since specializ ed honeydew collectors can shift from a no more rewarding aphid site t o other aphid sites of the same trail on which they develop a secondar y specialization. The ecological and behavioral aspects of the spatial specialization in L. fuliginosus are discussed with reference to the resource structure of the habitat.