Establishment of classical biological control targeting emerald ash borer is facilitated by use of insecticides, with little effect on native arthropod communities

William Davidson, Lynne K. Rieske

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Emerald ash borer, Agrilus planipennis (Coleoptera: Buprestidae), is rapidly invading North America and has inflicted extensive ash, Fraxinus spp., mortality in affected areas, altering composition and structure of wildland and urban forests. Insecticides can effectively protect ash on a small scale and classical biological control efforts have been implemented. In the U.S. emerald ash borer kills native ash so quickly, and populations are so mobile, that establishing an effective biological control program is challenging. Consequently, we assessed the compatibility of using reduced rates of the insecticide imidacloprid applied as a soil drench coupled with releases of three species of parasitic wasps. In this way we hope to slow the process of ash decline and prolong the window of opportunity to allow biological control agents to become established. We compared the efficacy and effects of i) full strength imidacloprid applications, ii) reduced rates of imidacloprid coupled with classical biological control, iii) classical biological control alone, and iv) untreated controls. We monitored emerald ash borer adult activity through trapping and destructive sampling for larvae, evaluated larval parasitization rates, and also assessed the native hymenopteran communities. Chemical treatments were not adequate to prevent ash canopy decline, but they also did not impede parasitization of emerald ash borer eggs or larvae. Two of the three classical biological control agents, Oobius agrili and Tetrastichus planipennisi, were recovered from trees treated with imidacloprid, demonstrating that they were successfully reproducing and indicating the compatibility of the two management strategies. Non-target hymenopterans appeared unaffected by the insecticide applications. Importantly we found no negative effects of the imidacloprid applications on native pollinators. Collectively these data suggest that judicious use of insecticides coupled with classical biological control may be an effective and potentially sustainable approach to managing invading populations of emerald ash borer.

Original languageEnglish
Pages (from-to)78-86
Number of pages9
JournalBiological Control
StatePublished - Oct 1 2016

Bibliographical note

Funding Information:
We thank Luke Dodd, Ignazio Graziosi, Zac Helton, Jon Johnson, Adrienne Kinney, Abe Nielsen, Matthew Savage, Chris Strohm, and Lee Townsend for providing assistance with field and laboratory work. Michael Sharkey and Eric Chapman assisted with parasitoid identification, Sarah Witt and Edward Roualdes with statistical analysis. John Obrycki, Lee Townsend, Dave Smitley, and three anonymous reviewers provided helpful comments to earlier drafts. We also thank Lee Crawfort, Bonnie Cecil, Taylorsville Lake State Park, Shelby County Parks and Rec., and Lexington-Fayette Urban County Government for providing access to land for this research. Parasitoids were provided by the USDA-APHIS-PPQ Biocontrol Rearing Facility in Brighton, MI. Funding was provided by the USDA Forest Service Special Technology Development Program , and McIntire Stennis Funds from the Kentucky Agricultural Experiment Station . This is Kentucky Agricultural Experiment Station number 16-08-020 and is published with the approval of the director.

Publisher Copyright:
© 2016 Elsevier Inc.


  • Agrilus planipennis
  • Imidacloprid
  • Invasive
  • Non-targets
  • Parasitoids
  • Pollinators
  • Sustainable

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Insect Science


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