Molecular epidemiology of Trichomonas gallinae in European Turtle Doves (Streptopelia turtur)

Abstract

Disease is usually ignored as a potential driver of species decline. This is concerning since disease could have a greater impact on a species as it becomes vulnerable to other extinction risks. This thesis investigated Trichomonas gallinae infection in the UK’s fastest declining farmland bird, the European Turtle Dove Streptopelia turtur. It employed molecular techniques to acquire data on parasite prevalence and identify strains, and trialled the application of Next Generation Sequencing technology to disease surveillance. Overall, 50 adult Turtle Dove samples from 2011-2015 were analysed and temporal variation in strain frequency was revealed. A degree of population structure in T. gallinae infecting different Turtle Dove populations (France 2014, n=40; Senegal, n=28) was apparent, along with some evidence of wide-ranging parasite dispersal, indirectly through their host. The potential risk of shared resources as a transmission route of T. gallinae was investigated with 226 food and 117 water samples screened for its presence. Evidence suggested T. gallinae was regularly present in both food and water resources. This has important implications for supplementary feeding being a conservation management tool. The reservoir of T. gallinae in the UK was reviewed by sampling potential hosts of Columbidae (n=166), Galliformes (n=13) and Passeriformes (n=90). The detection of strains other than the finch epidemic strain in free-ranging Passerines revealed a greater level of genetic heterogeneity than previously shown in other studies. There were no significant associations between T. gallinae strain infection or coinfection with haemosporidians and measures of reproduction, body condition or post-fledging survival in Turtle Doves however, sample sizes were small. Overall, this study increases our understanding of the epidemiology of T. gallinae both in the wider bird population and a species of Vulnerable conservation status. It demonstrates how T. gallinae infecting wild birds is a useful model for investigating aspects of host- parasite ecology and encourages further research with this system