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dc.contributor.authorMausel, Dave L.en_US
dc.date.accessioned2014-03-14T20:19:20Z
dc.date.available2014-03-14T20:19:20Z
dc.date.issued2007-11-15en_US
dc.identifier.otheretd-11292007-091928en_US
dc.identifier.urihttp://hdl.handle.net/10919/29785
dc.description.abstractDifferent Laricobius nigrinus Fender release locations, numbers of predators, and timing of release were evaluated for biological control of the hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae). It established at 59% of the sites and location was the most important factor related with establishment and abundance, HWA density, and hemlock vigor index. Cold locations had poor establishment or low abundance, declines in HWA density, and increases in hemlock vigor over time. Paired release and control sites detected a predator impact on HWA density, but densities remained high and tree vigor declined. The phenology of L. nigrinus, L. rubidus LeConte, and HWA were studied at a field insectary and the species were highly synchronized. A cage exclusion study showed that HWA survival and density were lower and ovisac disturbance was higher when exposed to predation. To improve L. nigrinus monitoring, we compared beat sheets for adults or branch clipping for immatures, and the host searching behavior of L. nigrinus was studied to understand how it locates a tree and HWA. In the Appalachians, beat sheet sampling resulted in false negatives as larvae were collected by branch clipping. Adults orientated to a tree visually, fed when prey were present and flew when absent, and showed different search patterns on infested versus uninfested trees. In Seattle, both sampling methods detected L. nigrinus because the predator was common. Predator : prey ratios were high at heavily infested sites in Seattle and low in the eastern US, where is has been released recently. Partial life tables were constructed for HWA sistentes at four sites for 2 yr in Seattle. Unspecified causes of nymph and adult mortality were high and L. nigrinus was the dominant predator of ovisacs. Adult L. nigrinus abundance was positively related to HWA density and immature abundance was related to ovisac density, indicating an aggregation and numerical response to its prey. Laricobius nigrinus has not demonstrated complete biological control of HWA to date, but it may do so in the future and continued release is justified.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartMausel_ETD.pdfen_US
dc.rightsI 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, dissertation, 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 Virginia Tech 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.en_US
dc.subjectsamplingen_US
dc.subjectlife tableen_US
dc.subjectobject orientationen_US
dc.subjecthost searching behavioren_US
dc.subjectAdelges tsugaeen_US
dc.subjectimpacten_US
dc.subjectsynchronyen_US
dc.subjectfield insectaryen_US
dc.subjectRelease methodologyen_US
dc.titleRelease and monitoring of Laricobius nigrinus (Coleoptera: Derodontidae) for biological control of the hemlock woolly adelgid in the eastern USen_US
dc.typeDissertationen_US
dc.contributor.departmentEntomologyen_US
dc.description.degreePh. D.en_US
thesis.degree.namePh. D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineEntomologyen_US
dc.contributor.committeememberOnken, Bradley P.en_US
dc.contributor.committeememberMcDonald, Richard C.en_US
dc.contributor.committeememberKuhar, Thomas P.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-11292007-091928/en_US
dc.contributor.committeecochairKok, Loke T.en_US
dc.contributor.committeecochairSalom, Scott M.en_US
dc.date.sdate2007-11-29en_US
dc.date.rdate2007-12-10
dc.date.adate2007-12-10en_US


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