Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - INVASIMMUN (The unseen adaptation of a non-native: A unique spatiotemporal study of infection dynamics and immunogenetics at a bioinvasion front)

Teaser

Emerging infectious diseases (EIDs) are an increasing threat to global health and there is an urgent need to understand the processes involved in their spread. The majority of EIDs originate from wildlife, for example the recent outbreaks of ebola, zika virus and lassa fever...

Summary

Emerging infectious diseases (EIDs) are an increasing threat to global health and there is an urgent need to understand the processes involved in their spread. The majority of EIDs originate from wildlife, for example the recent outbreaks of ebola, zika virus and lassa fever. One of the primary drivers of EIDs is human intervention via host or parasite translocations. A unique opportunity to study the processes involved in EIDs, currently exists in Ireland due to the introduction of the bank vole (Myodes glareolus), via Germany in the 1920’s. The continuing range expansion of the bank vole within Ireland presents a natural large-scale perturbation experiment, with empirical data and known expansion routes already available. The primary objective of the proposal is to conduct a spatiotemporal study analysing the infection dynamics of native and invasive species. A temporal study will allow the process of adaptation, as the invasive species becomes established, to be observed for the first time

Work performed

This study used the Irish Myodes glareolus model to conduct a spatiotemporal study analysing the parasite dynamics of native and invasive species throughout their range. M. glareolus and native Apodemus sylvaticus were trapped in woodlands across Ireland and surveyed for their helminth parasites. M. glareolus in Ireland were found to have lower parasite diversity in comparison to records of M. glareolus from across Europe and A. sylvaticus in Ireland. Increased density of M. glareolus resulted in a dilution effect, with significantly lower levels of parasitism overall in native hosts, where M. glareolus has been established longest. However, three helminth parasite species of A. sylvaticus increased in abundance in the presence of M. glareolus. Furthermore, M. glareolus at the expansion front were less parasitised than M. glareolus from the core population. This “enemy release” is believed to be mediating the continued successful spread of the invader across Ireland. Our results identify two important variables, seasonality and the stage of the invasion, which should not be overlooked when investigating or managing the changing distribution of hosts and their parasites.

Metagenomic of harmful bacteria also revealed an enemy release effect in M. glareolus in comparison to Irish woodmice and French bank voles (endemic range). Genera of bacteria of medical and veterinary importance were also detected. RNA was also extracted and libraries were made for immunological investigations.

Final results

Studies of bio-invasions and parasite transmission have primarily focused on the invasive host species or the native host species in cases where virulent pathogen spillover is observed. Our results demonstrate how the concurrent study of invasive and native hosts and the careful identification of their parasite communities allows the dynamic processes influencing the parasite component and intracommunity to be identified.

Website & more info

More info: https://www.tcd.ie/Zoology/research/groups/holland/research-group/peter.php.