Interactions between insect gut microbiotas and the environment

  • Calum Bridson

Student thesis: Phd


Gut microbes are ubiquitously associated with animals. These gut microbial communities have a range of important effects on host phenotypes. The particular functional effect that the microbiota has on the host depends on its composition, and therefore it is important to study the level of variation in the microbiota, as well as the factors that can drive changes in composition. The environment of the host has been shown to be able to influence the gut microbiota, but most of the focus has been on the role of diet, with limited attention paid to other variables. In particular, the role of anthropogenic activity and past environments remains uncertain. However, the interaction between the environment and gut microbiota is not just one way, with the gut microbes also able to influence how the host interacts with its environment. But the influence of gut microbes on host interactions with human-induced change is poorly understood. This thesis aims to increase our understanding of the interactions between insect gut microbiotas and the environment, specifically to extend our existing knowledge of three key areas: how the microbiota composition is distributed across a region; the environmental factors that shape the microbial composition; and how the microbiota influences the way in which the host interacts with a human-altered environment. The three chapters of the thesis addressed these aims by: characterising variation in honeybee gut microbiota across different land use types (Chapter 2); comparing the consumption of the fungicide chlorothalonil by germ-free and conventional bumblebees; and using a multi-generation experiment to determine whether the temperature a parent was raised at (parental temperature) had a stronger influence on offspring microbiota than the temperature the offspring were raised at (current temperature; Chapter 4). The key findings were that there was more variation within a honeybee hive than among hives (Chapter 2); that land use change, but not host genotype, can influence honeybee gut microbiota composition (Chapter 2); bumblebees that possess gut microbes consume more chlorothalonil solution than germ-free bees, which was driven by an aversion to chlorothalonil in germfree bees (Chapter 3); and parental temperature is more important for shaping gut microbiota composition than current temperature in cockroaches (Chapter 4).
Date of Award31 Dec 2020
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorWerner Muller (Supervisor) & Robert Gilman (Supervisor)


  • Land use
  • Trans-generational effects
  • Genotype
  • Pollinators
  • Insect feeding behaviour
  • Gut microbiota

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