Differential sunlight exposure affects settling behaviour of hemlock woolly adelgid crawlers

Download
(PDF; 787.0 KB)
Cite
Feedback
  • Authors: Mayfield, Albert E.; Jetton, Robert M.
  • Publication Year: 2020
  • Publication Series: Scientific Journal (JRNL)
  • Source: Agricultural and Forest Entomology
  • DOI: 10.1111/afe.12382

Abstract

1 Previous research demonstrated that elevated sunlight improves carbon balance and growth of eastern hemlock (Tsuga canadensis (L.) Carrière) seedlings infested with the invasive hemlock woolly adelgid (Adelges tsugae Annand).
2 This study examined the hypothesis that elevated visible and ultraviolet sunlight directly affects the settling behaviour of A. tsugae crawlers.
3 Hemlock seedlings were manually infested with equal densities of A. tsugae and placedintoartificialshadetreatments(0%,40%and80%shade).Thedensityofsettled nymphsoftheensuinggenerationonshadedseedlingswasthreetimeshigherthanthe density on unshaded seedlings.
4 Adelges tsugae ovisacs were also attached to hydrated hemlock branches placed beneath acrylic filter treatments that selectively allowed transmission of various sunlightwavelengths.Theproportionofadelgidcrawlersthatsettledonthebranch(vs. dropping from it) was higher beneath filters that blocked the widest spectrum of solar radiation (opaque and amber filters) than beneath full sun. In the March-April trial, exposure to full sun and the full visible spectrum only (clear-UV filter) significantly increased the proportion of crawlers that settled on the bottom (vs. top) side of the branch.
5 Our results suggest that A. tsugae crawlers are negatively phototactic and/or thermotactic, with behaviour influenced more by visible light than ultraviolet light.

  • Citation: Mayfield, Albert E.; Jetton, Robert M. 2020. Differential sunlight exposure affects settling behaviour of hemlock woolly adelgid crawlers. Agricultural and Forest Entomology. 56: 59-. https://doi.org/10.1111/afe.12382.
  • Keywords: Adelges tsugae, eastern hemlock, forest insects, invasive species, negative phototaxis, shade, Tsuga canadensis, ultraviolet light, visible light.
  • Posted Date: May 27, 2020
  • Modified Date: June 1, 2020

    • 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.