Trematodes of the family Didymozoid are parasites of marine fishes. The infection effects of the parasitic digenean trematode on the gill region of the fish Rastrelliger kanagurta were examined.

Human-induced growth of macro-algae is often assumed to increase trematode infections in fishes by increasing the abundance and condition of the parasite’s intermediate host – snails – as this can boost the release of trematode larvae, cercariae, from the intermediate hosts. However, macro-algae can also impose barriers to the transmission of cercariae and reduce infections. We investigated whe...

In some of the most complex animal societies, individuals exhibit a cooperative division of labour to form castes. The most pronounced types of caste formation involve reproductive and non-reproductive forms that are morphologically distinct. In colonies comprising separate or mobile individuals, this type of caste formation has been recognized only among the arthropods, sea anemones and mole-r...

Both theoretical arguments and empirical evidence suggest that parasite transmission depends on host density. In helminths with complex life cycles, however, it is not clear which host, if any, is the most important. Here, the relationships between the abundance of metacercariae in second intermediate hosts, and the local density of both the first and second intermediate hosts of two trematode ...

The intention to increase roach (Rutilus rutilus) consumption is in focus for ecological and economic reasons in Finland. However, its safety as food has not been considered comprehensively. We collected and artificially digested 85 roach halves originating from the south-eastern coast of Finland, and found trematode metacercariae in 98.8% of the samples. Based on polymerase chain reaction (PCR...

By modifying the behaviour and morphology of hosts, parasites may strongly impact host individuals, populations and communities. We examined the effects of a common trematode parasite on its snail host, Batillaria cumingi (Batillariidae). This widespread snail is usually the most abundant invertebrate in salt marshes and mudflats of the northeastern coast of Asia. More than half (52.6%, n=1360)...

Using controlled experiments, the ability of the trematode parasite Stegodexamene anguillae, encysted within its intermediate fish host, the common bully Gobiomorphus cotidianus, was tested to indirectly detect the presence of its definitive host by exposing infected G. cotidianus to chemical cues from the definitive host, the short-finned eel Anguilla australis. The trematode can abbreviate it...

The ability to culture parasites outside their host (i.e. in vitro) is essential for several aspects of parasitological research. Here, a culture medium for marine trematode parthenitae was optimized using Philophthalmus sp. rediae from the intermediate snail host, Zeacumantus subcarinatus. The medium was optimized by sequentially testing the suitability of different levels of osmolality, diffe...

In species assemblages of larval trematodes in individual snail hosts, fewer multispecies infections are observed than might be expected by chance. Both interspecific competition and the isolating effect of heterogeneity inrecruitment may explain this pattern of community structure. Here, we analyzed the expected and observed frequency of double infections, using data culled from 62 studies. Ou...

When hosts experience environmental stress, the quantity and quality of resources they provide for parasites may be diminished, and host longevity may be decreased. Under stress, parasites may adopt alternative strategies to avoid fitness reductions. Trematode parasites typically have complex life cycles, involving asexual reproduction in a gastropod first intermediate host. A rare phenomenon, ...