Investigating the association between diet and infection with Trichomonas gallinae in the European turtle dove (Streptopelia turtur)

Abstract

Trichomonas gallinae, a protozoan parasite infecting a wide range of birds, has been a cause for conservation concern since its recognition as an emerging infectious disease, having had notable impacts on several avian species, including causing widespread mortality in greenfinches (Chloris chloris), and chaffinches (Fringilla coelebs), and hindering the recovery of the endangered pink pigeon (Nesoenas mayeri). Horizontal transmission between birds congregating at feeding sites, such as those provided for conservation and species management purposes, is an important driver in the spread of T. galliane. Supplementary feeding is a key conservation intervention for the European turtle dove (Streptopelia turtur), which is declining across its range, driven at least partially by a loss of natural food resources. Due to the link between T. gallinae transmission and supplementary feeding, we consider the prevalence of this parasite among European turtle dove in relation to diet, in the first study to analyze these two factors in the decline of this species together. Using birds sampled from breeding and wintering grounds, the dietary composition of individuals was compared to the presence of T. gallinae, and specific T. gallinae strains. Dietary variation was summarized into two axes using detrended correspondence analysis; neither was associated with the presence of T. gallinae or any specific strains. The proportion of diet accounted for by cultivated seeds did not affect parasite presence, despite the spread of this parasite being associated with supplementary feeding due to an increase in contact between potentially infected and uninfected birds gathering at high densities at feeding sites. Significant dietary overlap was observed between infected and uninfected individuals in all sites, with almost complete dietary overlap being observed in one breeding site. The level of dietary overlap between individuals infected with specific strains fluctuated between sampling seasons, indicating no consistent relationship between diet and infection status.

Introduction to special issue: Advancing disease ecology through eDNA monitoring of infectious agents

“…Using molecular methods to survey parasites and pathogens from environmental samples has the potential to complement conventional methods and ameliorate some of the aforementioned challenges. Environmental DNA sequencing methods can improve our understanding of the spatiotemporal dynamics of pathogens and parasites across a diversity of systems by enabling more geographically widespread sampling (Jahan et al, 2023;Sieber et al, 2023;Young et al, 2023). The high frequency of surveillance with eDNA can lead to both the rapid update of genetic databases and increased effectiveness of conservation and management plans.…”

“…They surveyed multiple sites in Senegal, Hungary, and France to determine if supplemental feeding sites spread the protozoan parasite, Trichomonas gallinae. Because supplemental feeding sites have previously been implicated in the horizontal transmission of T. gallinae in species of conservation concern, Young et al (2023) expected to find a correlation between the proportion of cultivated seeds in the diet and T. gallinae infection. While there was no consistent association between diet and infection status, this study highlights the potential of eDNA to gain insights into the transmission of diseasecausing organisms through diet ecology.…”

“…By taking advantage of when nonvector animals come into contact with animals or their by-products, Jahan et al (2023) revealed new phylogenetic diversity of Bcbva and generated cooccurrence data on the rapidly changing geographic ranges of both host and pathogen. Young et al (2023) added an extra dimension to a large-scale metabarcoding project by assessing whether diet facilitated protozoan infection of the European turtle dove, Streptopelia turtur. They surveyed multiple sites in Senegal, Hungary, and France to determine if supplemental feeding sites spread the protozoan parasite, Trichomonas gallinae.…”