Environmental and behavioral factors associated with the infestation of vineyards by larvae of grape root borer

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dc.contributor.authorRijal, Jhalendra P.en
dc.contributor.committeechairBergh, J. Christopheren
dc.contributor.committeememberZhang, Aijunen
dc.contributor.committeememberPfeiffer, Douglas G.en
dc.contributor.committeememberTholl, Dorotheaen
dc.contributor.committeememberLeskey, Tracy C.en
dc.contributor.committeememberBrewster, Carlyle C.en
dc.contributor.departmentEntomologyen
dc.date.accessioned2014-04-04T08:00:32Zen
dc.date.available2014-04-04T08:00:32Zen
dc.date.issued2014-04-03en
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
dc.description.degreePh. D.en
dc.format.mediumETDen
dc.identifier.othervt_gsexam:2342en
dc.identifier.urihttp://hdl.handle.net/10919/46871en
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectVitacea polistiformisen
dc.subjectVitis viniferaen
dc.subjectgeostatisticsen
dc.subjectSADIEen
dc.subjectsamplingen
dc.subjectrisk factorsen
dc.subjectCATPCAen
dc.subjectlogistic regressionen
dc.subjectbelowground herbivoryen
dc.subjectbehavioren
dc.subjectsoil columnen
dc.subjectbioassayen
dc.subjectroot volatilesen
dc.subjectexuviaeen
dc.titleEnvironmental and behavioral factors associated with the infestation of vineyards by larvae of grape root boreren
dc.typeDissertationen
thesis.degree.disciplineEntomologyen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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