PhD defence: Nicolas De Pelsmaeker

Nicolas De Pelsmaeker from USN’s PhD program in Ecology will defend his thesis for the degree of PhD: Altitudinal distribution and host-parasite relations of ticks in Norway.

05 Mar

Practical information

  • Date: 5. March 2021
  • Time: 10.00 - 14.00
  • Location: Bø, 5-115, Zoom
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    10.00: Trial lecture: 'How can (and cannot) studies along elevational gradients be used to understand the ecological implications of climatic change?'

    11.15: Public defence: Nicolas De Pelsmaeker defends his PhD thesis 'Altitudinal distribution and host-parasite relations of ticks in Norway.'

    Evaluation Committee

    • Dr. Jolyon Medlock, Head of Medical Entomology of Public Health England, London, UK 
    • Professor Stein Joar Hegland, Department of Environmental Sciences, Western Norway University of Applied Sciences
    • Dr. Veronica Tinnesand, Department of Natural Sciences and Environmental Health, USN

    Leader of the defence

    • Professor Andreas Zedrosser, Department of Natural Sciences and Environmental Health, USN

    Main supervisor

    • Associate Professor Øyvind Steifetten, Department of Natural Sciences and Environmental Health, USN


    • Associate Professor Lars Korslund, Department of Natural Sciences, University of Agder

About the thesis:

Nicolas De PelsmaekerRising temperatures due to climate change is allowing ticks to expand to new areas and to increasingly higher altitudes. This brings an increased risk of becoming infected with tick-borne diseases to new places.

We found that ticks are occurring at higher altitudes than previously thought on Norwegian mountains. The results of our study show that in two locations in the east and west of southern Norway, ticks can now be found up to at least 1000 meters above sea level, and possibly even higher, whereas the highest altitude previously found was 583 meters. Further studies may tell us what the current maximum altitude is at which ticks can survive in Norway, as well as what the occurrence of tick-borne diseases on Norwegian mountains.

Furthermore, the low abundances of some hosts during periodic population cycles in rodents may not inhibit the future progression of ticks to higher altitudes, as other small animals may have the potential to compensate for the periodic lack of rodents.

These findings push us to re-evaluate disease risk to both humans and wild animals in mountainous areas, as well as to livestock (e.g. sheep) that graze freely in the mountains outside of the winter season.