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The crayfish plague pathogen Aphanomyces astaci in its introduced ranges: vectors, introduction pathways, genetic variation and host-pathogen interactions
Mrugała, Agata ; Petrusek, Adam (advisor) ; Füreder, Leopold (referee) ; Vralstad, Trude (referee)
- ABSTRACT - The crayfish plague pathogen, Aphanomyces astaci, is responsible for substantial declines and local extinctions of native European crayfish populations. As a consequence, the pathogen is now listed among 100 world's worst invasive alien species. The spread of A. astaci is greatly facilitated by its natural hosts, North American crayfish, that thanks to a long co-evolutionary history with the crayfish plague pathogen evolved efficient defence mechanisms. In contrast, European, Australian and Asian crayfish species are highly susceptible to this disease agent. However, progress of A. astaci infection in native European crayfish was observed to differ between distinct pathogen strains, indicating variability in their virulence. Indeed, we demonstrated a relationship between patterns in crayfish immune response and A. astaci virulence in an experimental infection involving the European noble crayfish and three differently virulent crayfish plague strains. The European continent is currently inhabited by at least eight North American crayfish species. The carrier status was confirmed in six of them, including also Orconectes cf. virilis occurring in the Netherlands and the UK. In this country, we detected Aphanomyces astaci presence in some populations of the non-indigenous crayfish species as well...
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Detection, distribution, diversity and phylogeny of the crayfish plague pathogen Aphanomyces astaci (Oomycetes)
Kozubíková, Eva ; Petrusek, Adam (advisor) ; Dunn, Alison M. (referee) ; Füreder, Leopold (referee)
My Ph.D. thesis deals with various aspects of research of the crayfish plague pathogen, Aphanomyces astaci (Oomycetes). Crayfish plague decimates whole populations of European crayfish; therefore, it is one of the main problems for conservation of these species endangered from other reasons as well. The infection is transmitted by invasive North American crayfish, which are much less susceptible to the disease and are apparently original hosts of A. astaci. The core of this thesis consists of six studies. Four of them have been already published, the remaining two are manuscripts under review. The main linking motive among the presented studies is not only the crayfish plague pathogen itself, but also the use, development and verification of the reliability of molecular detection methods of A. astaci and its genotypes. This core of the thesis is further divided into two parts. The first one contains four studies that deal with the distribution of A. astaci in North American crayfish populations in the Czech Republic (Chapter 1) and Hungary (Chapter 2), and factors influencing this distribution. Two North American crayfish species can be found in the wild in these countries, the spiny-cheek crayfish (Orconectes limosus) and the signal crayfish (Pacifastacus leniusculus). The first two chapters show...
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