In the invasive crab Carcinus maenas, parasite loss during
its introduction was previously suggested as a main reason for
invasion success. This hypothesis was examined by analysing parasite
impacts on individual fitness. However, I found little support for it.
Apart from the effect of parasitic castrators the crabs were mostly
unaffected by the more common helminth parasites. A major regulatory
role of parasites in the home range or parasite release during the
invasion are therefore unlikely.