Assessing the potential role of lagomorphs as reservoirs in maintaining metapopulations of parasites of veterinary and agricultural significance

Abstract

Significant production losses are associated with agricultural parasites. The ultilisation of pasture by both lagomorphs (rabbits, hares and pika) and domestic livestock creates potential for inter-species parasite transmission, thus lagomorphs may contribute to the dynamics of livestock parasites and to the spread of anthelmintic resistance. This thesis investigated wild lagomorphs as potential sources of parasites of veterinary significance. A global review suggests 572 parasite species have been reported from lagomorphs, but almost half of all lagomorphs species were entirely data deficient. Of these 154 species are of potential significance in veterinary medicine most notably the gastrointestinal nematodes, liver fluke and arthropods capable of vectoring disease. The community composition of lagomorph parasites in Ireland has been historically understudied with this study expanding the record of documented parasites in Irish lagomorphs with the addition of five species. Parasitism was common in both European rabbits(Oryctolagus cuniculus) and Irish hare (Lepus timidus hibernicus) populations in Ireland, with life history traits and seasonal changes impacting burdens. Species richness was higher in rabbits (17 species) than in hares (6 species), but only two of the recovered species: the tick, Ixodes ricinus and liver fluke, Fasciola hepatica are of agricultural significance. Both occurred infrequently suggesting lagomorph populations are not significant reservoirs but infected individuals may contribute to parasite dynamics at the local level. Helminth populations are influenced both by host factors and other parasite species within the ecological community of the host. The only species common in both hosts, T. retortaeformis, differed in its distribution along the small intestine in rabbits and hares. Interspecies interactions between parasite species were also evident with positive effects of cestodes on G. strigosum intensity, G. strigosum on T. retortaeformis intensity and T. retortaeformis on P. ambiguus intensity. Coprological techniques present a possible alternative to necropsy for the non-invasive detection of helminth and protozoal parasites. The modified Cornell-Wisconsin method exhibited significant benefits over the McMaster techniques for the detection of nematode and cestode eggs and coccidial oocysts, while sedimentation was effective for the detection of trematode eggs. These techniques could be used for the non-invasive study of parasite prevalence in wild lagomorph populations, but their ability to predict worm burdens is limited, however, these technique are of limited usefulness in the prediction of helminth burdens as egg counts were only weakly related to trichostrongylid worm burdens. The pattern of infection in Irish lagomorph populations shared many similarities with rabbit and hare populations elsewhere, however, differences in the coinfections and inter-parasite interactions that may be due to ecological differences between populations. As lagomorph infections with ruminant helminths are uncommon, lagomorphs in Ireland are not significant reservoirs of livestock helminths, therefore, the integration of lagomorph control into parasite management plans cannot currently be supported. However, the potential for the emergence of livestock parasites in lagomorphs remains, therefore, ongoing monitoring and surveillance is advised.

Date of Award	Jul 2024
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	Northern Ireland Department for the Economy
Supervisor	Neil Reid (Supervisor) & Nikki Marks (Supervisor)