41st Annual Meeting of the Society for Invertebrate Pathology
and 9th International Conference on Bacillus thuringiensis

Microsporidia from freshwater Amphipods were only recently the focus of intensive research. Based on a literature review, an overview will be first presented, including data on molecular systematic, transmission (vertical vs. horizontal), fitness effects for the host (feminization…), host ranges and geographical distribution. Parasitism as a component of the success and dynamic of invasions, as well as the potential impact of alien parasites on the local fauna are regarded as important factors. Therefore, this paper will also present ongoing research on a newly characterised microsporidia, Microsporidium sp. D, infecting the invasive amphipod Dikerogammarus villosus. Originating from the Ponto-Caspian area, D. villosus invaded almost all large rivers of Europe in less than 30 years. PCR-RFLP typing showed that M. sp. D followed its host almost all along its invasion route. In an attempt to test if M. sp. D is a way to control the invader or/and a risk for the local fauna, results about transmission (vertical vs. horizontal) and potential impact on host fitness as well as prevalence and pathogenicity to the local fauna will be presented for two invaded areas contrasting by their invasion history and local fauna: Burgundy (France) and Eastern Poland.