title: Impact of the goldspotted oak borer, Agrilus auroguttatus, on the health of coast live oak before and after treatment with two systemic insecticides.
abstract: BACKGROUND
  The invasive goldspotted oak borer, Agrilus auroguttatus, is threatening the health and survival of oak trees in San Diego County, California. From two sites in the core area of the infestation, we report a 2.5 year investigation of the impact of A. auroguttatus on coast live oak, Quercus agrifolia, before and after treatment with two systemic insecticides, emamectin benzoate (EB) and imidacloprid (IC).
  
  
  RESULTS
  None of the 446 survey trees died during the study. The crown dieback rating of most trees at both study sites remained unchanged, regardless of insecticide treatment. A higher cumulative increase in the number of A. auroguttatus emergence holes was observed on trees that were previously infested and on trees with larger diameters. Over the 2.5 year period, the new infestation rates of initially uninfested trees across the untreated and treated groups were 50% (EB) and 32% (IC), and neither EB nor IC treatment affected cumulative increases in the number of emergence holes. EB-injected trees did not have significant annual increases in the number of A. auroguttatus emergence holes at either 1.5 or 2.5 years compared with that at 0.5 years, whereas untreated trees had significant annual increases. Although IC-injected trees had a significantly greater annual increment in the number of emergence holes than untreated trees during the last year of the study, treated trees had significant reductions in annual increases in emergence holes at both 1.5 and 2.5 years compared with that at 0.5 years. Untreated trees had no significant reduction in the annual increase in emergence holes at 1.5 and 2.5 years.
  
  
  CONCLUSIONS
  A. auroguttatus preferentially attacked previously infested and larger (diameter at breast height > 15-30 cm) oak trees, but the attacks led to very gradual changes in the health of the trees. Both EB and IC provided minor suppressive effects on A. auroguttatus emergence. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
authors.affiliation: Department of Entomology and Nematology, University of California, Davis, CA, USA.
authors.forename: Yigen
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Entomology and Nematology, University of California, Davis, CA, USA.
authors.forename: Mary L
authors.initials: ML
authors.lastname: Flint
authors.affiliation: USDA Forest Service, Forest Health Protection, San Bernardino, CA, USA.
authors.forename: Tom W
authors.initials: TW
authors.lastname: Coleman
authors.affiliation: Arborjet Inc., Woburn, MA, USA.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Doccola
authors.affiliation: Arborjet Inc., Woburn, MA, USA.
authors.forename: Donald M
authors.initials: DM
authors.lastname: Grosman
authors.affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Wood
authors.affiliation: USDA Forest Service, Pacific Southwest Research Station, Davis, CA, USA.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Seybold
mesh_terms: D000818:Animals; D002140:California; D001517:Coleoptera; D007093:Imidazoles; D007300:Insect Control / Q000379:methods; D007306:Insecticides; D058865:Introduced Species; D007559:Ivermectin / Q000031:analogs & derivatives*; D000073943:Neonicotinoids; D009574:Nitro Compounds; D029963:Quercus / Q000469:parasitology*
chemical_list: D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; C082359:imidacloprid; D007559:Ivermectin; C108024:emamectin benzoate
keywords: Buprestidae; Coleoptera; Quercus agrifolia; emamectin benzoate; imidacloprid; invasive species