Authors

A K Chambers²; F Kenyon¹; D Nussey⁴; R Avramenko³; E Redman³; J Gilleard³; J Pilkington⁴; N D Sargison²;  ¹ Moredun Research institute;  ² The Royal (Dick) School of Veterinary Studies and the Roslin Institute, The University of Edinburgh;  ³ University of Calgary;  ⁴ University of Edinburgh, Institute of Evolutionary Biology

Discussion

Host fitness is heavily influenced by the presence of co-infecting parasites, and understanding intraspecific dynamics is important in gaining an insight into host health. Previous methods of nematode burden assessment are low-throughput and have limited sensitivity, which prevents fine-scale partitioning of species. Researching the nematode biome structure in the absence of control measures is required to recognise the impact of management decisions on sustainable control. The unmanaged Soay sheep on St Kilda provides an ideal study population. ~ 1000 faecal samples were collected over 8 sampling months, from 9 different sex-age groups. These were used for faecal egg counting using a cuvette salt floatation method, and were incubated to grow 3^rd stage larvae for molecular analyses.  The development of a deep sequencing assay of the ITS-2 region of the rDNA cistron has enabled the accurate identification and quantification of clade V species, with this being the first field application of this method. Preliminary analyses of the sequencing data recovered all five species previously identified on St Kilda, with seasonal, age and sex differences in species composition. Additionally, cyclic trends have been observed, with key strongyle species sequentially peaking throughout the year. These seasonal differences appear to correspond with the sheep's dynamic life-history. Correcting for species-specific sequencing biases, amplicon repeatability and species detection threshold, ensures this method is repeatable.