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One Gifford Pinchot Drive
Madison, WI 53726
(608) 231-9318
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Emerald Ash Borer

Overcoming Obstacles to Interspecies Hybridization of Ash

Research Issue

[photo:]  Fraxinus spaethiana accession from University of Tokyo Botanical Gardens, Japan.In contrast to the high levels of devastation observed on North American ash species infested with emerald ash borer (Agrilus planipennis, EAB), reports from Asia indicate that EAB-induced destruction of Asian ash species is limited to stressed trees.  Thus Asian ash species have co-evolved resistance or at least a high degree of tolerance to this insect. We are investigating whether inter-species hybrids of Asian and North American ash species can be used to introgress EAB resistance into native ash species.

 Our Research

We have identified five pressing research needs plus a sixth long-term goal; these are to: 

  1. Access and replicate Asian ash trees
  2. Confirm species identity, clonal ID, and relatedness of Asian ash accessions
  3. Determine ploidy level of all species and individual trees where ploidy varies within species
  4. Develop methods to overcome obstacles to hybridization such as species differences in pollination system and phenology
  5. Determine which Asian ash species are resistant and the level of variability within species
  6. Identify resistance to EAB in exotic ash species and/or select North American individuals ("lingering ash") for use in establishing a breeding program.   The use of exotic ash species to generate F1 hybrids may have immediate value to the nursery industry as street trees.  F1 progeny as well as subsequent generations will also be valuable genetic resources for determining the heritability and molecular mechanisms of resistance through the use of genomics, transcriptomics, proteomics, and metabolomics.  Backcross generations created through careful selection of parents for both North American characteristics and EAB resistance may someday provide the resources needed to re-establish EAB-resistant North American ash species in our forests.  Gene conservation involving North American ash species is a critical component of such a breeding program so that genetic diversity across the native range is preserved for use in later generations of breeding.

Expected Outcomes

  • Obtain Asian ash species and establish them at the U.S. Forest Service Northern Research Station facility in Delaware, Ohio
  • Confirm species identification of all ash species, especially Asian species
  • Determine if Asian ash species are resistant to EAB
  • Generate novel EAB-resistant ash hybrids

Research Results

Koch, Jennifer L.; Carey, David W.; Mason, Mary E. 2008. Development of novel ash hybrids to introgress resistance to emerald ash borer into North American ash species In: Mastro, Victor; Lance, David; Reardon, Richard; Parra, Gregory, comps. Emerald ash borer research and development meeting; 2007 October 23-24; Pittsburgh, PA. FHTET 2008-07. Morgantown, WV: U.S. Department of Agriculture, Forest Service, Forest Health Technology Enterprise Team: 36-37.

Koch, Jennifer L.; Carey, David W.; Larson, Richard. 2007. Host resistance to emerald ash borer: development of novel ash hybrids In: Gottschalk, Kurt W., ed. Proceedings, 17th U.S. Department of Agriculture Interagency Research Forum on Gypsy Moth and Other Invasive Species, 2006. Gen. Tech. Rep. NRS-P-10. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 58.

Research Participants

Principal Investigators

  • Jennifer Koch, Research Biologist, U.S. Forest Service, Northern Research Station

Research Partners

  • Therese Poland, Research Entomologist, U.S. Forest Service, Northern Research Station
  • Dan Herms, Professor and Associate Chairperson, The Ohio State University, Department of Entomology, Ohio Agricultural Research and Development Center
  • Nurul Faridi, Research Geneticist, U.S. Forest Service, Southern Research Station

Last Modified: 12/07/2017

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