1:45 PM - 2:00 PM [7-18-02] Insights into the critical periods and molecular mechanisms underlying nutritional polyphenism in the cherry-oat aphid Rhopalosiphum padi *Aurelie Etier1, Rituparna Ghosh1, Théo Vericel1, Sylvain Guillot1, Maïwenn Le Floch1, Romuald Cloteau1, Nathalie Prunier-Leterme1, Stéphanie Robin1, Fabrice Legeai1, Gaël Le-Trionnaire1, Jean-Christophe Simon1 (1. UMR- 1349 IGEPP, INRAE, 35650 Le Rheu (France))