Background/Question/Methods The potato tuberworm (PTW) Phthorimaea operculella (Zeller) is one of the most important constraints to potato productivity worldwide. It was first detected in northeastern Oregon in 2002. Due to increased PTW population densities, economic losses have increased substantially in the Columbia Basin from 2004 to 2005. We collected samples from several locations, including Washington, Idaho, California, Virginia, and Georgia in order to compare samples obtained from Oregon. Using molecular markers (AFLP), and cluster analyses (neighbor joining), the present study assessed the population structure of PTW in the Columbia Basin.

Results/Conclusions We found that in the US PTW populations seem to be divided in a western and eastern fashion. The Appalachian Mountains could partially be acting as a geographic barrier for this insect isolating eastern and western populations. Western populations seem to subdivide in two sub-groups: One northern and one southern. The Rocky Mountains could act as an effective geographic barrier isolating these two sub-populations.