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dc.contributor.authorBarker, Christopher Michaelen_US
dc.date.accessioned2014-03-14T20:43:49Z
dc.date.available2014-03-14T20:43:49Z
dc.date.issued2001-07-10en_US
dc.identifier.otheretd-08202001-224533en_US
dc.identifier.urihttp://hdl.handle.net/10919/34652
dc.description.abstractRecently, the number of human cases of La Crosse encephalitis (LACE), an illness caused by mosquito-borne La Crosse (LAC) virus, has increased in southwestern Virginia, resulting in a need for better understanding of the virus cycle and the biology of its vectors in the region. This project examined the spatial and temporal distributions of the primary vector of LAC virus, Ochlerotatus triseriatus, and a potential secondary vector, Aedes albopictus. Ovitrapping surveys were conducted in 1998 and 1999 to determine distributions and oviposition habitat preferences of the two species in southwestern Virginia. For virus assay, adult mosquitoes were collected at a tire dump and a human case site during 1998 and 1999, and ovitrap samples were taken from a human case site in 2000. In a separate study, a landcover map of Wise County was created by supervised classification of Landsat Enhanced Thematic Mapper imagery, and maps indicating posterior probabilities of high mosquito abundance were created by combining ovitrap survey-derived, landcover-based prior and conditional probabilities for high and low mosquito abundance using remote sensing techniques and Bayesian decision-making rules. Both Oc. triseriatus and Ae. albopictus were collected from all ovitrap sites surveyed in Wise, Scott, and Lee Counties during 1998. Numbers of Oc. triseriatus remained high from late June through late August, while Ae. albopictus numbers increased gradually through June and July, reaching a peak in late August and declining thereafter. Overall, Oc. triseriatus accounted for 90.1% of eggs collected during this period, and Ae. albopictus made up the remaining 9.9%. Abundance of the two species differed among the sites, and in Wise County, relative Ae. albopictus abundance was highest in sites with traps placed in open residential areas. Lowest numbers of both species were found in densely forested areas. Ovitrapping at a human LACE case site during 1998 and 1999 revealed that Aedes albopictus was well-established and overwintering in the area. An oviposition comparison between yard and adjacent forest at the Duncan Gap human LACE case site in 1999 showed that Ae. albopictus preferentially oviposited in the yard surrounding the home over adjacent forested areas, but Oc. triseriatus showed no preference. LAC virus was isolated from 1 larval and 1 adult collection of Oc. triseriatus females from the Duncan Gap human case site, indicating the occurrence of transovarial transmission at this site. The supervised landcover classification for Wise County yielded a landcover map with an overall accuracy of 98% based on comparison of output classification with user-defined ground truth data. Posterior probability maps for Oc. triseriatus and Ae. albopictus abundance reflected seasonal and spatial fluctuations in mosquito abundance with an accuracy of 55-79% for Oc. triseriatus (Kappa=0.00-0.53) and 70-94% for Ae. albopictus (Kappa=0.00-0.49) when model output was compared with results of an ovitrapping survey. Other accuracy measures were also considered, and suggestions were offered for improvement of the model.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartFinalThesis.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.subjectgeospatial modelingen_US
dc.subjectLa Crosse virusen_US
dc.subjectAedes albopictusen_US
dc.subjectOchlerotatus triseriatusen_US
dc.titleBionomics of Ochlerotatus triseriatus Say (Diptera: Culicidae) and Aedes albopictus Skuse (Diptera: Culicidae) in emerging La Crosse virus foci in Virginiaen_US
dc.typeThesisen_US
dc.contributor.departmentEntomologyen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineEntomologyen_US
dc.contributor.committeechairPaulson, Sally L.en_US
dc.contributor.committeememberLuckhart, Shirleyen_US
dc.contributor.committeememberApperson, Charles S.en_US
dc.contributor.committeememberBrewster, Carlyle C.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-08202001-224533/en_US
dc.date.sdate2001-08-20en_US
dc.date.rdate2002-08-22
dc.date.adate2001-08-22en_US


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