Potato virus Y (PVY) and Potato leafroll virus (PLRV) are the most important aphid-transmitted viruses in potato. Historically, control of virus spread has been through the use of pesticides to control vectors. However, insecticides are of inconsistent benefit in preventing virus spread, especially for nonpersistently transmitted viruses like PVY. A goal of the Minnesota Potato Breeding Program has been to discover resistance to green peach aphid, Myzus persicae (Sulzer) and potato aphid, Macrosiphum euphorbiae (Thomas), and to use marker assisted selection to advance cultivar breeding. Over the past seven years, we subjected 174 advanced potato lines to intensive selection for resistance to these pests. One line that has consistently expressed resistance to both aphids was crossed with cv Chieftain to produce an F₁ population. Aphids were tested for survivorship, development, reproduction and adult longevity on 30 F₁ progeny. Life tables were constructed and intrinsic rates of increase (r_m) were calculated. For green peach aphid, r_m ranged from 0.042 to 0.311. For potato aphid, r_m ranged from -0.077 to 0.161. We are currently screening resistant and susceptible plants using a bulked segregant analysis approach with AFLP and SSR markers which will be used to guide aphid resistance integration into current potato cultivars. In addition, we are using electrical penetration graphs to record feeding behavior on resistant and susceptible plants. With these techniques, we expect to ascertain whether the resistance(s) expressed in our potato lines are due to antixenosis or antibiosis.