1. University of Padova, DAFNAE; Agripolis, Viale dell'Università, 16, 35020 Legnaro, PD Italy
2. INRA; Unité de Recherche de Zoologie Forestière, 2163, Avenue de la pomme de pin-Ardon CS 40001; 45075 Orléans France
3. Department of Zoology; Stockholm University; Svante Arrheniusväg 18 B, SE-106 91 Stockholm Sweden