What's Inside? An Examination of the Characteristic Microbiome of Prairie Grasshoppers and Katydids

Date of Award

2020

Degree Name

M.S. in Biology

Department

Department of Biology

Advisor/Chair

Advisor: Yvonne Sun

Abstract

There are many ways in which microbiomes can influence the health and fitness of their insect hosts. While much research has been done on the microbiomes of economically important species like honeybees, and charismatic groups like butterflies, little work has been done to understand the microbiome of grasshoppers and katydids. Grasshoppers are an important herbivore in grassland ecosystems and provide important ecosystem services like nutrient cycling. Alternatively, grasshoppers can be a pest organism requiring management and control. In relationship to the total ecosystem, the limitation of abiotic factors like essential nutrients can influence the abundance and fitness of insect herbivores such as grasshoppers. However, the effect of these abiotic factors on grasshopper microbiomes is largely unknown. Using culture-independent, high-throughput 16s and ITS sequencing and statistical analysis, we examined the gut microbiome of six species of grasshoppers (n=60) from the site of a fully-factorial fertilization experiment in a coastal tallgrass prairie ecosystem in order to gain a better understanding of the microbial communities present across the orthopteran order in this ecosystem. We also examined the relationship between environmental nutrients and gut microbes of one orthopteran species, Orchelimum vulgare. Our observations support the hypothesis that there is a "core" group of bacterial families in these grasshopper species and factors such as trophic behaviors and the evolution of the host may contribute to the shifts in prevalence among these core microbial groups. We also found significantly higher Shannon diversity in the gut bacterial communities of those grasshoppers from plots fertilized with added sodium in contrast to plots without sodium. There is significantly lower diversity in gut fungal communities from plots amended with nitrogen and phosphorus, as well as sodium, suggesting that both nitrogen and phosphorus and sodium are limiting nutrients for the fungal community. There was also a strong positive correlation between bacterial and fungal diversity within each sample. These results support the hypothesis that environmental nutrients will alter the characteristic gut microbiome of O. vulgare, though these alterations will be different for bacterial and fungal communities. ?

Keywords

Biology, Ecology, insect microbiome, grasshoppers, prairie, nutrient limitation, fungal microbiome

Rights Statement

Copyright © 2020, author

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