Systemically Applied Insecticides for Treatment of Erythrina Gall Wasp, Quadrastichus erythrinae Kim (Hymenoptera: Eulophidae)

  • Authors: Doccola, Joseph J.; Smith, Sheri L.; Strom, Brian L.; Medeiros, Arthur C.; von Allmen, Erica.
  • Publication Year: 2009
  • Publication Series: Miscellaneous Publication
  • Source: Arboriculture & Urban Forestry, Vol. 35(4): 173-181

Abstract

The erythrina gall wasp (EGW), believed native to Africa, is a recently described species and now serious invasive pest of Erythrina (coral trees) in tropical and subtropical locales. Erythrina are favored ornamental and landscape trees, as well as native members of threatened ecosystems. The EGW is a tiny, highly mobile, highly invasive wasp that deforms (galls) host trees causing severe defoliation and tree death. The first detection of EGW in the United States was in O´ahu, Hawai´i in April 2005. It quickly spread through the Hawai`ian island chain (U.S.) killing ornamental and native Erythrina in as little as two years. At risk are endemic populations of Erythrina as well as ornamental landscape species in the same genus, the latter of which have already been killed and removed from O´ahu at a cost of more than USD $1 million. Because EGW are so small and spread so quickly, host injury is usually detected before adult wasps are observed, making prophylactic treatments less likely than therapeutic ones. This study evaluates two stem-injected insecticides, imidacloprid (IMA-jet®) and emamectin benzoate, delivered through Arborjet Tree I.V.® equipment, for their ability to affect E. sandwicensis (wiliwili) canopy demise under severe EGW exposure. IMA-jet, applied at a rate of 0.16 g AI/cm basal diameter (0.4 g AI/in. dia.), was the only effective treatment for maintaining canopy condition of wiliwili trees. Emamectin benzoate, applied at a rate of ~0.1 g AI/cm basal diameter (~0.25 g AI/in. dia.), was not effective in this application, although it was intermediate in effect between IMA-jet and untreated trees. The relatively high concentrations of imidacloprid in leaves, and its durability for at least 13 months in native wiliwili growing on a natural, dryland site, suggest that treatment applications against EGW can impact canopy recovery even under suboptimal site and tree conditions.

  • Citation: Doccola, Joseph J.; Smith, Sheri L.; Strom, Brian L.; Medeiros, Arthur C.; von Allmen, Erica. 2009. Systemically Applied Insecticides for Treatment of Erythrina Gall Wasp, Quadrastichus erythrinae Kim (Hymenoptera: Eulophidae). Arboriculture & Urban Forestry, Vol. 35(4): 173-181
  • Keywords: Coral Trees, Emamectin Benzoate, Erythrina sandwicensis, Imidacloprid, Tree Injection, Wiliwili
  • Posted Date: August 5, 2009
  • Modified Date: August 5, 2009
  • Print Publications Are No Longer Available

    In an ongoing effort to be fiscally responsible, the Southern Research Station (SRS) will no longer produce and distribute hard copies of our publications. Many SRS publications are available at cost via the Government Printing Office (GPO). Electronic versions of publications may be downloaded, printed, and distributed.

    Publication Notes

    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
    • Our online publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact the SRS webmaster if you notice any errors which make this publication unusable.
    • To view this article, download the latest version of Adobe Acrobat Reader.