Date of Award

December 2019

Document Type


Degree Name

Master of Science (MS)


Environmental Engineering and Earth Sciences

Committee Member

Michael S Caterino

Committee Member

Peter H Adler

Committee Member

Sharon Bewick

Committee Member

Matthew W Turnbull


Adult and larval Holometabolous insects exhibit radically different gut morphologies tied to their differing natural histories. Additionally, like other animals, these organisms frequently show distinctive morphological and physiological partitioning of their digestive systems, and this reflects on resident microbial communities. A review of the literature reveals bacteria have formed various symbioses with holometabolous hosts, differing widely in the context of host-symbiont services and patterns of colonization. The significance of these organisms in shaping host evolution and vice-versa is, at present, unclear, but intriguing in the context of host phylogeny.

Using high throughput 16S amplicon sequencing, the bacterial community of the digestive tract of adults and larvae of the common North American scarab species Cotinis nitida is characterized according to life stage, gut structure, and adult sex. Through statistical analysis of sequence data, I show that the bacterial communities of the digestive system differ significantly between adults and larvae in both taxon richness and relatedness, and that no major differences exist between adult male and adult female beetles in terms of bacterial community. Significant differences are observed between the midgut and hindgut regions in adult beetles. The partitioning between communities of bacteria in the digestive system of larvae is displayed through significant differences in two distinct hindgut regions, the ileum and the expanded paunch., while there is no significant difference between the midgut and ileum portion of the hindgut region in larvae.



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