Degree
Doctor of Philosophy (PhD)
Department
Entomology
Document Type
Dissertation
Abstract
The Formosan subterranean termite, Coptotermes formosanus, initiates colonies with a monogamous pair of swarming reproductives (alates), that shed their wings (dealates) to become king and queen of the incipient colony. The first offspring depends on nutritional resources from the founding pair and their gut microbiota consisting of cellulose-digesting protozoa, bacteria, and archaea. Although subterranean termites rely on their gut microbiota for cellulose digestion, understanding of the core microbiota’s composition and influence on termite biology, especially in founder pairs, remains limited.
This thesis has four chapters. The first chapter contains the introduction and literature overview. Chapter 2 through 4 describe the three research objectives. In chapter 2, we investigated how gut microbiota of dealates influence pair formation. We found that higher body weight and protozoa numbers were associated with increased likelihood of pair formation in naturally paired dealates, emphasizing the importance of nutritional resources and microbial symbionts in this process. However, bacterial diversity determined by 16S rRNA gene sequencing showed no influence on pair formation. In the third chapter, we tracked the dynamic changes in body weight, protozoa abundance, and bacterial diversity in colony founders during the initial 170 days of colony development. These variables exhibited a similar dynamic pattern, peaking around 25 to 50 days post-colony foundation, then declining with the emergence of the first workers, indicating a transition from biparental care to alloparental care. The core bacteria predominantly consisted of phylum Bacteroidota and the protozoa endosymbiont Candidatus Azobacteroidetes. Furthermore, we observed correlations of the top-five dominant bacterial phyla and fourteen core bacterial taxa with protozoa abundance, emphasizing the importance of symbiotic interactions between bacteria and protozoa in the incipient colony. In Chapter 4 we investigated the distribution of two bacteriophage genomes previously identified from C. formosanus workers and their putative host bacteria Candidatus Azobacteroides pseudotrichonymphae (CAP) across the geographic range of C. formosanus and related species. These two novel bacteriophages were functionally annotated, and specific primers were developed for PCR detection of the two phages and their host bacterium. We detected both bacteriophages in different Coptotermes species from native and introduced ranges, and in both worker and reproductive castes. Phylogenetic analyses indicated congruent evolution between CAP and Coptotermes related genera; but phage diversification was not related to termite speciation.
Date
5-24-2024
Recommended Citation
Chen, Junyan, "Investigation of the core microbiota of the Formosan subterranean termite, Coptotermes formosanus (Blattodea: Rhinotermitidae): its impact on pair formation, changes during early colony development and geographic diversity of bacteriophages" (2024). LSU Doctoral Dissertations. 6492.
https://repository.lsu.edu/gradschool_dissertations/6492
Committee Chair
Husseneder, Claudia
DOI
https://doi.org/10.31390/gradschool_dissertations.6492