Effects of fertilizer and low rates of Imidacloprid on Adelges tsugae (Hemiptera: Adelgidae).

  • Authors: Joseph, S. V.; Hanula, James; Braman, S. K.; Byrne, F. J.
  • Publication Year: 2011
  • Publication Series: Scientific Journal (JRNL)
  • Source: J. Econ. Entomol. 104(3):868-878

Abstract

Healthy hemlock trees, Tsuga canadensis (L.) Carriere, and hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), populations should favor retention and population growth of adelgid predators such as Laricobius nigrinus Fender (Coleoptera: Derodontidae) and Sasajiscymnus tsugae (Sasaji&McClure) (Coleoptera: Coccinellidae). Eastern hemlock trees between 15 and 38 cm diameter at breast height (dbh) were treated with 0, 10, or 25% of 1.5 g imidacloprid (Merit 75 WP) per 2.5 cm dbh and were either fertilized or not, in a 3 by 2 factorial design. After 2 yr, imidacloprid reduced the numbers of ovisacs and eggs found on trees in a dosage-dependent manner, while enhancing tree growth parameters such as new shoots or needles and the length of new shoots. Fertilized trees had greater adelgid fecundity, which was positively correlated with total foliar N in both winter generations. In February 2009 (27 mo after imidacloprid treatment), higher imidacloprid dosages to unfertilized trees resulted in reduced adelgid fecundity. Concentrations of N, P, and K were higher in the foliage of trees treated with insecticide, whereas foliar aluminum concentrations were consistently lower in trees with higher insecticide dosages. Trees treated with low rates of imidacloprid were healthier than untreated trees, but only trees treated with the 0.1 x dosage had suffcient adelgids to possibly sustain predators over extended periods.

  • Citation: Joseph, S.V.; Hanula, J.L.; Braman, S.K.; Byrne, F.J. 2011. Effects of fertilizer and low rates of Imidacloprid on Adelges tsugae (Hemiptera: Adelgidae). J. Econ. Entomol. 104(3):868-878.
  • Keywords: hemlock woolly adelgid, eastern hemlock, predators, imidacloprid, fertilizer
  • Posted Date: June 3, 2011
  • Modified Date: July 15, 2011
  • 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.