Population Structure of Phthorimaea Operculella (Lepidoptera: Gelechiidae): Origins of the Columbia Basic Populations

NON-TECHNICAL SUMMARY: The potato tuberworm has recently been detected for the first time in Oregon (in 2002), Washington (in 2005) and Idaho (in 2005). This project provides insights into the origin of Oregon, Washington and Idaho potato tuberworm populations. This information will help reduce further spread or introductions into new areas.

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APPROACH: The present project will allow us to infer if the Potato tuberworm (PTW) populations found in the lower Columbia Basin (Oregon and Washington) and Idaho are part of a pre-established population that is expanding its range or if populations are migrating from close or distant reproductively isolated populations. In 2006, PTW adults will be collected from potato fields in Oregon, Washington and Idaho and from potato fields in major potato production areas in neighboring states (i.e. California, Arizona, New Mexico and Utah). Samples from other U.S. production areas (i.e. Maryland, Virginia, and Florida) and from South America and New Zealand will also be collected to be used as comparison groups. Samples from the Northwestern Uinted States, including the Columbia basin, will be collected by an already extended PTW working group headed by Oregon State University and Washington State researchers and stakeholders. All specimens will be sent to Dr. Medina for molecular analyses. Adult moths will be collected, killed and shipped in 70-100% alcohol. Molecular markers (i.e., AFLP), will be used to infer the origin of PTW in the lower Columbia Basin and Idaho using cluster analysis (i.e., Neighbor joining). Population structure will be corroborated using Fst values. If PTW individuals in the lower Columbia Basin and Idaho are migrating from neighboring structured populations, we will be able to pinpoint their origin by looking at their clustering pattern. In contrast, if PTW populations neighboring the lower Columbia Basin and Idaho are not structured, the absence of genetic differences between Oregon, Washington and Idaho populations and their neighbors will indicate range expansion of an adjacent large population. Upon completion of the present project, our findings will be made available as base information via presentations, web information, and fact sheets. Disseminating this information in a timely manner is critical to the industry. Dr. Rondon is responsible of coordinating the extension activities in Oregon and Washington. Idaho will be included in this tri-State effort. We will: 1) Publish relevant articles in Potato Progress (research and extension newsletter of the Washington State Potato Commission (WSPC)), trade magazines, and on the Oregon State University-Hermiston Agricultural Research and Extension Center (HAREC)and WSPC websites (www.oregonstate.edu/Dpt/hermiston and www. potatoes.com) ; 2) Present research results and information throughout the year in English and Spanish through briefings at commodity/industry meetings.
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PROGRESS: 2006/07 TO 2008/06 <BR>
OUTPUTS: This project has provided information on the population structure of the potato tuber worm in the United States. The relatively high number of potato tuberworms observed in 2004 and 2005 in the Columbia Basin naturally declined in 2006 and 2007. Thus we could not obtain as many samples as we were planning to obtain. However, the number of samples we gathered was enough to describe the population structure of the potato tuberworm across the US. Results from this research will be disseminated in a newsletter, a publication in a peer reviewed journal and in a poster at the Ecological Society of America meeting in Milwaukee. <BR> PARTICIPANTS: Raul F. Medina, Texas A&M University (PI) Silvia Rondon, Oregon State University (Co-PI) Francis Dimtri, Texas A&M University (undergraduate assistant) The current grant allowed us to train an undergraduate student in molecular methods and analyses. TARGET <BR> AUDIENCES: The target audiences for this project include the scientific community working on population distribution and population substructure and the applied community worried about potato tuber worm introductions in the Columbia Basin. The relatively high population numbers of potato tuber worm observed in Oregon and Idaho in 2004 and 2005 generated interest on the potential origin of this pest on those areas. <BR> <BR>
IMPACT: 2006/07 TO 2008/06<BR>
This study has described the population substructure of the potato tuber worm in the United States. A western and an eastern independent population have been found. The western population has been further subdivided into a northern and southern population. The apalachian and rocky mountains may be acting as geographical barriers for the potato tuber worm in the United States. Potato tuber worm populations in Idaho and Oregon appeared to have originated within the west coast. Future studies centering on the western populations only are needed to further pinpoint the origin of the Columbia Basin potato tuber worms. The present study allowed us to trained an undergraduate student in molecular techniques. This undergraduate student will be presenting our results from this project in a poster at the Ecological Society of America annual meeting in Milwaukee this August (2008).