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dc.contributor.authorZilahi-Balogh, Gabriella M. G.en_US
dc.date.accessioned2014-03-14T20:19:12Z
dc.date.available2014-03-14T20:19:12Z
dc.date.issued2001-11-09en_US
dc.identifier.otheretd-11252001-154726en_US
dc.identifier.urihttp://hdl.handle.net/10919/29737
dc.description.abstractThe biology of Laricobius nigrinus Fender (Coleoptera: Derodontidae) and its potential for control of hemlock woolly adelgid (HWA), Adelges tsugae Annand (Homoptera: Adelgidae) in the eastern United States were investigated. Laricobius nigrinus completed development on HWA in laboratory studies. There are four larval instars. Mean larval consumption was 225.9 and 252.3 HWA eggs at 12 and 18 ° C, respectively. Post-aestivation activity period was 36.6 and 30.8 weeks for males and females at 13 ° C, respectively. Mean lifetime fecundity was 100.8 eggs over a mean ovipositional period of 13.2 weeks. Laricobius nigrinus is host specific. In paired-choice and no-choice oviposition tests, L. nigrinus laid more eggs in HWA ovisacs than other test species. Laricobius nigrinus consumed more eggs of HWA than eggs of Adelges piceae (Ratzeburg) and Pineus strobi (Hartig) but not of Adelges abietis (L.). In larval development tests, L. nigrinus only completed development on HWA. A two-year field study conducted in British Columbia showed that: 1) the life cycle of HWA in British Columbia is similar to that previously reported in Virginia and Connecticut; 2) L. nigrinus adults undergo an aestival diapause that coincides with the diapause of the first instar HWA sistens. Adult activity beginning in autumn coincides with resumption of development of the sistens generation; 3) oviposition and subsequent larval development of L. nigrinus coincide with oviposition by HWA sistens adults. Temperature-dependent development was determined for egg, larval, pre-pupal and pupal stages of L. nigrinus at five constant temperatures (9, 12, 15, 18 and 21 ° C). Development time was inversely proportional to temperature between 9 and 18 ° C. Laricobius nigrinus did not complete development at 21 ° C. Minimum developmental temperatures for eggs (6.5 ° C), larvae (5.1 ° C), pre-pupae (3.8 ° C), and pupae (3.1 ° C) were determined by extrapolation of linear regression equations to the x-intercept. Degree-days calculated for eggs, larvae, pre-pupae, pupae, and egg to adult were 54.6, 161.3, 196.1, 212.8, and 666.7, respectively. The laboratory derived degree-day model for predicting egg hatch was validated with field data collected in British Columbia. Observed median egg hatch at three of four sites over two years was within 15% of the predicted DD value (54.6).en_US
dc.publisherVirginia Techen_US
dc.relation.haspartDissert_REV.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.subjectAdelges tsugaeen_US
dc.subjectbiologyen_US
dc.subjectAdelgidaeen_US
dc.subjectDerodontidaeen_US
dc.subjectLaricobius nigrinusen_US
dc.subjectbiological controlen_US
dc.titleBiology of Laricobius nigrinus Fender (Coleoptera: Derodontidae) and its potential as a biological control agent of the hemlock woolly adelgid, Adelges tsugae Annand (Homoptera: Adelgidae) in the eastern United Statesen_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.committeechairKok, Loke T.en_US
dc.contributor.committeememberHumble, Leland M.en_US
dc.contributor.committeememberFell, Richard D.en_US
dc.contributor.committeememberPfeiffer, Douglas G.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-11252001-154726/en_US
dc.contributor.committeecochairSalom, Scott M.en_US
dc.date.sdate2001-11-25en_US
dc.date.rdate2002-11-28
dc.date.adate2001-11-28en_US


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