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dc.contributor.authorRijal, Jhalendra Prasaden_US
dc.date.accessioned2014-04-04T08:00:32Z
dc.date.available2014-04-04T08:00:32Z
dc.date.issued2014-04-03en_US
dc.identifier.othervt_gsexam:2342en_US
dc.identifier.urihttp://hdl.handle.net/10919/46871
dc.description.abstractGrape root borer, Vitacea polistiformis (Harris), is an oligophagous pest of grapevines in the eastern USA. Neonates must burrow into the soil to find grape roots. In Virginia, larvae feed on roots for ~2 years, then pupate just beneath the soil surface. Emerging adults leave an empty pupal exuviae at the soil surface around the vine base. There was no relationship between weekly captures in pheromone traps and pupal exuviae counts, indicating that exuviae sampling is most appropriate to assess infestations. Exuviae sampling in Virginia vineyards revealed infestations that ranged from light to very heavy. Eighteen biotic and abiotic variables were measured and used in analyses that assessed their relative contributions to differences in exuviae density. Water holding capacity and clay/sand ratio were most strongly associated with pupal exuviae density; these variables were used to develop a model for predicting the extent of infestation of individual vineyards. The spatial distribution of pupal exuviae was characterized using non-spatial and geospatial techniques. Although the non-spatial method (Taylor's Power Law) indicated that exuviae showed an aggregated distribution in all blocks, spatial methods (variograms, SADIE) revealed aggregated distributions only in blocks with ≥ 0.5 pupal exuviae per vine. Independent pupal exuviae samples for population assessment in vineyards can be achieved using sampling points separated by >8.8 m. Combined results from geospatial analyses and the temporal distribution of pupal exuviae within years enabled the development of a practical and quantitative sampling protocol. Bioassays used to measure the behavioral response of larvae to host stimuli revealed that neonates were attracted to grape root volatiles. In soil column bioassays, larvae moved vertically and horizontally over distances of up to 120 cm and apparently perceived the presence of grape roots from a distance of 5 cm in soil. Results are discussed in relation to their potential implications for monitoring and managing grape root borer.en_US
dc.format.mediumETDen_US
dc.publisherVirginia Techen_US
dc.rightsThis Item is protected by copyright and/or related rights. Some uses of this Item may be deemed fair and permitted by law even without permission from the rights holder(s), or the rights holder(s) may have licensed the work for use under certain conditions. For other uses you need to obtain permission from the rights holder(s).en_US
dc.subjectVitacea polistiformisen_US
dc.subjectVitis viniferaen_US
dc.subjectgeostatisticsen_US
dc.subjectSADIEen_US
dc.subjectsamplingen_US
dc.subjectrisk factorsen_US
dc.subjectCATPCAen_US
dc.subjectlogistic regressionen_US
dc.subjectbelowground herbivoryen_US
dc.subjectbehavioren_US
dc.subjectsoil columnen_US
dc.subjectbioassayen_US
dc.subjectroot volatilesen_US
dc.subjectexuviaeen_US
dc.titleEnvironmental and behavioral factors associated with the infestation of vineyards by larvae of grape root boreren_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.committeechairBergh, J. Christopheren_US
dc.contributor.committeememberZhang, Aijunen_US
dc.contributor.committeememberPfeiffer, Douglas G.en_US
dc.contributor.committeememberTholl, Dorothea Berta Christineen_US
dc.contributor.committeememberLeskey, Tracy C.en_US
dc.contributor.committeememberBrewster, Carlyle C.en_US


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