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Mountain pine beetle-caused mortality, host selection, and preformed tree defenses in lodgepole and ponderosa pine of the Front Range, Colorado

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dc.contributor.authorWest, Daniel R., author
dc.contributor.authorJacobi, William, advisor
dc.contributor.authorBriggs, Jenny, committee member
dc.contributor.authorSibold, Jason, committee member
dc.contributor.authorBjostad, Louis, committee member
dc.date.accessioned2007-01-03T05:54:12Z
dc.date.available2014-09-30T05:54:08Z
dc.date.issued2013
dc.description.abstractEruptive mountain pine beetle (Dendroctonus ponderosae) populations that developed in the late 1990's and early 2000's over the southern Rocky Mountains have resulted in widespread pine-mortality throughout the region. Concerns escalated in 2007 as to whether northern Colorado ponderosa pine- (P. ponderosa) dominated stands were susceptible to attack from beetles moving from adjacent stands of mountain pine beetle killed lodgepole pine (P. contorta var. latifolia). Early observations by A. D. Hopkins suggested alternate host species are unlikely to sustain attack from beetles that developed in a different host species. This dissertation addressed the research question of whether mountain pine beetles were likely to infest ponderosa pine trees from populations that developed within lodgepole pine. I used three approaches to answer the question: 1) a monitoring survey of Front Range, CO., USA, lodgepole-ponderosa pine ecotone stands for five time periods (2004-7, 8, 9, 10, 11) to quantify mortality levels in both host species (Chapter1); 2) a controlled-field choice experiment where beetles that developed in either lodgepole or ponderosa pine were offered cut-logs of both lodgepole and ponderosa pine (Chapter 2); and 3) a bioassay where individual female mountain pine beetles that developed in either host species were offered bark/phloem units of both host species (Chapter 2). Results from monitoring mountain pine beetle-caused mortality indicated both species were attacked in similar proportions over time. Both the controlled-field studies and laboratory bioassays of mountain pine beetle host selection found beetles preferred ponderosa pine over lodgepole pine 2:1. Results from the choice experiments were consistent with the findings of primary host selection in laboratory bioassays, indicating beetle behavior in the presence of aggregation pheromones within the field arenas was no different than host selection behavior in the absence of aggregation pheromones in the bark/phloem laboratory bioassay arenas. The initial conifer defenses against bark beetle attack are preformed quantitative and qualitative defenses produced prior to being wounded or attacked. The objective of Chapter 3 was to assess the preformed (24-hr) oleoresin defenses of lodgepole pine and ponderosa pine in mixed pine ecotone stands. The amounts of exuded preformed oleoresins - the quantitative defenses - were almost four times greater in ponderosa pines than lodgepole pines. Differences were found in all but three of the constitutive monoterpenes - the qualitative defenses - between the two tree species. Greater concentrations of limonene, β-phellandrene, and cymene were identified in lodgepole pine than ponderosa pine oleoresins. The monoterpenes of β-pinene, 3-carene, myrcene, and terpinolene were all greater in ponderosa pine than lodgepole pine oleoresins. Although we found differences both in quantitative and qualitative preformed oleoresin defenses, hypotheses linking the ecological relevance of these differences to bark beetle susceptibility have not been tested. The results from the field monitoring surveys where both species were attacked in similar proportions differ from the findings of the choice tests where the beetles infested greater proportions of ponderosa pine logs than lodgepole pine logs. I infer that, under natural conditions, the greater amount of oleoresin flow and/or the amount of specific monoterpenes in ponderosa pine oleoresin compared to lodgepole pine may have limited the rate of mass attacks on ponderosa pine and served to equilibrate the amount of mortality we recorded in both species in the forest stands. To my knowledge, this is the first documentation of mountain pine beetles infesting both lodgepole pine and an alternate host, ponderosa pine, at landscape scales during epidemic conditions in Colorado. Managers should be aware there are no apparent major host characteristics the mountain pine beetle cannot overcome that might prevent the movement from lodgepole pines into ponderosa pines. Rather, my results indicate that the availability, condition, and defense capability of host trees influence their susceptibility to the mountain pine beetle.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.identifierWest_colostate_0053A_11900.pdf
dc.identifier.urihttp://hdl.handle.net/10217/80197
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subjectdefenses
dc.subjectmountain pine beetle
dc.subjectlodgepole pine
dc.subjecthost selection
dc.subjectponderosa pine
dc.subject.lcshDendroctonus ponderosae
dc.titleMountain pine beetle-caused mortality, host selection, and preformed tree defenses in lodgepole and ponderosa pine of the Front Range, Colorado
dc.typeText
dcterms.embargo.expires2014-09-30
dcterms.embargo.terms2014-09-30
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineBioagricultural Sciences and Pest Management
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)

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