Symbiotic communities and interactions in two major bark beetle systems relative to climate and tree chemical defenses

Vissa, Sneha (2022) Symbiotic communities and interactions in two major bark beetle systems relative to climate and tree chemical defenses. Doctoral thesis, Northern Arizona University.

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Abstract

Bark beetle-killed trees are reservoirs of biodiversity in forest ecosystems. Bark beetles are associated with a variety of symbionts with whom they share complex ecological interactions. Symbiota of bark beetles directly and indirectly affect beetle population dynamics, which in turn determines [tree] host colonization, tree condition, and even landscape-level tree mortality patterns. Thus, bark beetle activities collectively shape forest ecosystems. These complex symbiotic interactions in bark beetle systems involve multiple biological groups, including fungi, bacteria, mites, nematodes, and the tree itself (their living biotic environment). These interactions are also climate dependent and can vary across large geographic scales. This variability in symbiotic community association is important for understanding beetle-disturbance patterns, identifying important co-evolutionary relationships, and for modeling climate-driven biotic shifts in various bark beetle systems that are locally adapted to their native environments. In this dissertation, I use large-scale geographic surveys to compare and contrast symbiotic community assemblages for an economically important bark beetle species (Dendroctonus ponderosae); and use a hypothesis-driven field experimental study to show that these community assemblages are locally adapted and respond variably to warming climates. Considering the susceptibility of conifers to bark beetles to climate-change driven drought, I also use field studies of pinyon bark beetle (Ips confusus) in a drought stressed pinyon pine environment to provide important information regarding tree chemical profiles in relation to bark beetles and climate. I use lab experimental studies to show that biotic tree responses (such as resin production and chemical profile) in drought stressed trees can influence the growth of fungi that are symbionts with pinyon bark beetles. I conclude this dissertation by summarizing the major ecological/ecosystem contributions of bark beetle symbionts and discuss the potential for direct management and the implications for existing management practices.

Item Type:	Thesis (Doctoral)
Publisher’s Statement:	© Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords:	Bark Beetles; Climate; Fungi; Mites; Symbiosis; Terpenes
Subjects:	S Agriculture > SD Forestry
NAU Depositing Author Academic Status:	Student
Department/Unit:	Graduate College > Theses and Dissertations College of the Environment, Forestry, and Natural Sciences > School of Forestry
Date Deposited:	07 Jun 2023 16:45
Last Modified:	07 Jun 2023 16:45
URI:	https://openknowledge.nau.edu/id/eprint/5977

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