ORCID Identifier(s)

ORCID 0000-0001-5382-7704

Graduation Semester and Year

Summer 2024



Document Type


Degree Name

Doctor of Philosophy in Biology



First Advisor

Alison Ravenscraft


Animals are highly dependent on microbial symbionts for nutrient supplementation, parasite protection, toxin resistance, and more. While these microbes are important, these associations have the potential to shift from mutualistic to parasitic across environments and over time. Eight insect families from the hemipteran infraorder Pentatomomorpha have evolved a highly specialized relationship with bacteria in the genus Caballeronia. The symbiont is a free-living microbe, acquired from the environment each generation during early host development. By manipulating environmental conditions, I used the bug-Caballeronia model 1) to investigate whether symbionts with greater growth rates at high temperatures prevent hosts from experiencing performance declines at high temperatures, 2) to evaluate and compare symbiont gene expression under thermal stress between in vitro and in vivo conditions, and 3) to elucidate the prevalence and functional effects of symbiosis-associated genomic elements. Through a combination of insect rearing, diagnostic techniques, and genomic analyses, I evaluated the mechanistic and genomic factors associated with this environmentally acquired symbiont. Caballeronia strain identity was identified as a primary factor in forming a successful symbiosis, as well as contributing to host thermal performance. Overall, my work suggests that the flexibility provided by this symbiosis may improve host suitability within their local environment despite the risk associated with having to acquire a new symbiont each generation. Therefore, strain level variation may aid populations in adapting to stressors, with the individuals possessing optimal strains surviving stressful events.


Caballeronia, Genomic island, Heat shock genes, Heteroptera, Leptoglossus phyllopus, Symbiosis, Thermal stress


Entomology | Environmental Microbiology and Microbial Ecology


Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Available for download on Thursday, June 04, 2026