Biological control, host resistance, and vegetative propagation were evaluated as management strategies for the exotic pest hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae) in the southeastern U.S. Biological control studies focused on the adelgid predator Sasajiscymnus tsugae Sasaji and McClure. In the laboratory, the suitability of an alternative prey species balsam woolly adelgid (BWA), Adelges piceae Ratz., for predator feeding, oviposition, immature development, and long-term survival was compared to the primary prey HWA. The BWA was found to be a suitable host to support predator feeding and development but was found to negatively influence S. tsugae survival. Field studies of S. tsugae tested the utility of multi-point, low-density, confined releases in mesh sleeve cages as an alternative to a routinely utilized single-point, high-density, free release for introducing the predator to forest and ornamental sites in Western North Carolina. The studies found that S. tsugae will reproduce inside sleeve cages and can survive for up to one month in confinement, but field establishment of the predator could not be confirmed. In the greenhouse a method for artificially inoculating hemlock seedlings with HWA and comparing levels of host resistance among hemlock species was tested. Using this method, initial infestation rates and fecundity of HWA were compared among three species of hemlock native to North America: eastern hemlock (Tsuga canadensis), Carolina hemlock (T. caroliniana), and western hemlock (T. heterophylla). Infestations were significantly and four-fold higher on eastern hemlock compare to those on Carolina and western hemlock that did not differ. A second greenhouse trial assessed the rooting ability of softwood stem cuttings from mature specimens of eastern and Carolina hemlock. The study found that eastern hemlock cuttings rooted best with no hormone applications and at higher rates than Carolina hemlock which required very low concentrations of auxin.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-08252008-094603 |
| Date | 04 September 2008 |
| Creators | Jetton, Robert Miller |
| Contributors | David Orr, John Frampton, John Monahan, Fred Hain, Dan Robison |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-08252008-094603/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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