Graduation Semester and Year
Summer 2026
Language
English
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Biology
Department
Biology
First Advisor
Alison Ravenscraft
Second Advisor
Luke O. Frishkoff
Third Advisor
Laura D. Mydlarz
Fourth Advisor
Mathew R. Walsh
Fifth Advisor
Joseph Boll
Abstract
Most multicellular organisms depend on their microbial symbionts for various functions, such as digestion, nutrient supplementation, pesticide degradation, and defense. While many insects acquire their symbionts vertically from their parents, thousands of species of true bugs (Hemiptera) across different families acquire their microbial symbiont, Caballeronia, from the environment each generation. Acquiring symbionts from the environment (horizontal transmission) has various ecological consequences for the host. In this study, I used the bug-Caballeronia model 1) to understand whether the free-living symbionts benefit from association with multicellular hosts, 2) to evaluate whether host specialization on symbiont strains varies across taxonomic levels, and 3) to understand how desiccation affects survival of environmentally acquired symbionts and, as a result, performance of the host. I use a combination of insect rearing, cell culture, and various molecular techniques to understand the ecological dynamics underlying the horizontally transmitted bug-Caballeronia symbiosis. In summary, my work suggests that 1) bug- Caballeronia symbiosis is beneficial for the free-living Caballeronia population, 2) squash bugs tend to be more specialized on their own Caballeronia symbionts, but leaffooted bugs have equivalent fitness regardless of strain origin, and 3) symbiont strains vary in desiccation tolerance, and host survival varies with both strain and soil moisture but sometimes in unexpected ways. The ecological dynamics underlying this symbiosis are shaped by a complex interplay among reciprocal benefits to the symbionts, varying degrees of host specialization on Caballeronia between host species, and environmental conditions such as soil moisture.
Keywords
Symbiosis, Host-microbe interaction, insect, mutualism, Bug-Caballeronia, cost-benefit, specialization, desiccation
Disciplines
Biology | Entomology | Environmental Microbiology and Microbial Ecology
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Parajuli, Bibek Singh, "THE ECOLOGICAL CONSEQUENCES OF HORIZONTAL TRANSMISSION OF SYMBIONTS" (2026). Biology Dissertations. 4.
https://mavmatrix.uta.edu/biology_dissertations2/4
Included in
Biology Commons, Entomology Commons, Environmental Microbiology and Microbial Ecology Commons