Lice lessons: using biochemical analyses of external parasites to reconstruct past host lives

Mortier, G. G. (2026) Lice lessons: using biochemical analyses of external parasites to reconstruct past host lives. PhD thesis, University of Reading. doi: 10.48683/1926.00129059

Abstract/Summary

This thesis explores how blood-feeding ectoparasites such as lice, fleas, and ticks can be used as tools to reconstruct aspects of host diet, health, and life history. Despite acting as sources of ecological and biochemical information on their hosts, ectoparasites remain underrepresented in collections-based studies. To provide context, the historical relationship between humans and their ectoparasites is reviewed, highlighting the shifts in societal perspectives alongside growing conservation concerns. This research examined the application of ectoparasites for biochemical analysis of their hosts by establishing a modern methodological testbed for stable isotope analysis to reconstruct host dietary ecology and feeding patterns, as well as conducting molecular analyses to recover host DNA using a targeted capture enrichment approach. In addition, the occurrence of ectoparasites preserved on natural history specimens was investigated to assess the feasibility of using such material and gather information regarding host behaviour and health. Findings from the stable isotope analyses showed that ectoparasites mirror their hosts’ isotopic signatures and therefore reflect their dietary patterns, albeit to varying degrees depending on taxon and the presence of blood meals, whereas the molecular analysis of tick blood meals recovered host mitochondrial DNA at levels sufficient for population genetics. Finally, the examination of ectoparasite traces on museum specimens led to the discovery of a new louse species, whose significance was contextualised through the dietary ecology of its extinct host, the thylacine (Thylacinus cynocephalus). These results underscore the potential of ectoparasites to act as archives of biological and ecological information on their hosts, with the methods established in this project providing a foundation for further applications in the fields of wildlife conservation, biomonitoring, evolutionary studies, archaeology, and vector borne disease ecology.

Item Type	Thesis (PhD)
URI	https://centaur.reading.ac.uk/id/eprint/129059
Identification Number/DOI	10.48683/1926.00129059
Divisions	Science > School of Archaeology, Geography and Environmental Science > Department of Geography and Environmental Science
Date on Title Page	October 2025
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