The invasion of the greater white toothed shrew, to Ireland, and its effects on the parasitic prevalence in the native pygmy shrew 

Cooper, Ella

Abstract

The invasive greater white-toothed shrew (Crocidura russula) was first recorded in Ireland in
2007, where its range has since expanded at an alarming rate and caused the displacement
of the native pygmy shrew (Sorex minutus). As well as displacing local populations, invasive
species can greatly impact the native host-parasite relationships. This study aims to explore
how the invasion of the greater, white-toothed shrew has affected such dynamics between
the pygmy shrew and their associated blood parasites and ectoparasites. Samples, of both
species, have been previously collected across radial transects in the south of Ireland during
two different seasons, where their hearts were harvested and their bodies were
preserved. Shrews were also collected from Belle Île, an island off northwestern France
where the two species coinhabit, to act as a control. Detection of Babesia spp., Anaplasma
phagocytophilum, Hepatozoon spp. and Bartonella spp. was achieved through DNA
extractions, PCR, and further DNA sequencing, whilst ectoparasites were identified after
being combed from the bodies. Statistical analysis, involved Chi-squared tests and
generalised linear models, showed that Bartonella spp. prevalences were significantly higher
in the zones inside the invasion and during the spring sampling season, indicating Bartonella
spp. host specificity and vector seasonality. Overall tick prevalence and intensity, in the Irish
shrews, was significantly affected by location, whilst being significantly greater in Belle Île
pygmy shrews. Low prevalences of A. phagocytophilum and Hepatozoon spp. in Irish shrew
populations, as well as the lack of Babesia spp. was also shown. Moreover, the fleas
Ctenophthalmus nobilis nobis, Nosopsyllus fasciatus and Rhadinopsylla pentacantha, were
identified from Irish shrews, with the latter being absent from Belle Île. Consequently, this
study provides complementary data on how the invasion has affected the native pygmy
shrew population in Ireland, which is valuable information for understanding the associated
invasion mechanisms.

Citation

Cooper, E. (2024). The invasion of the greater white toothed shrew, to Ireland, and its effects on the parasitic prevalence in the native pygmy shrew . (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Aug 30, 2024
• Publicly Available Date: Sep 27, 2026
• Award Date: Sep 26, 2024