Comparison of parasite communities in native and introduced populations of sexual and asexual mollies of the genus Poecilia

The parasite communities of two molly species, the sexual Poecilia latipinna and the clonalPoecilia formosa, were investigated in four populations using a novel method applicable under field conditions. In two native populations from south Texas and two introduced populations from central Texas, four species of microparasites and eight species of macroparasites were recorded. Virtually no differences in the parasite diversity and species composition could be detected between the populations. Mollies from south Texas had a higher individual parasitization index of macroparasites. There was a negative correlation between the relative number of oocytes in gravid females and their individual macroparasite load. # 2005 The Fisheries Society of the British Isles