Occurrence of Bunodera luciopercae (Digenea: Allocreadiidae) in fish from Hanningfield Reservoir, Essex

Influence of Triaenophorus nodulosus plerocercoids (Cestoda: Pseudophyllidea) on the occurrence of intestinal helminths in the perch (Perca fluviatilis)

Concurrent infections of helminths in vertebrates are widespread and may demonstrate synergistic, antagonistic or negligible levels of interactions between species that share a common site. However, indirect interactions between species that occur in different organs of a host are poorly documented, particularly in fish. Plerocercoids of Triaenophorus nodulosus are common liver infections of European perch (Perca fluviatilis). These larval cestodes cause extensive liver damage, resulting in systemic pathologies that include alteration of the physiochemical environment of the intestine. Perch harbour a wide range of intestinal helminths whose occurrence may be potentially influenced by the concurrent presence of T. nodulosus plerocercoids. The present study, using an existing dataset, investigated the effects of T. nodulosus on the infection levels of four common perch helminths - Acanthocephalus lucii, Camallanus lacustris, Proteocephalus percae and Bunodera luciopercae. The prevalences of A. lucii and C. lacustris were significantly reduced in fish infected by T. nodulosus, although the mean intensity of infections remained unaffected for any helminth species, while the mean abundance of C. lacustris was significantly reduced in plerocercoid-affected perch. Differences in site selection and individual interactions between the four helminth species in the intestine of T. nodulosus-infected and non-infected perch were rarely observed.

Patterns of macroparasite abundance and aggregation in wildlife populations: a quantitative review

In this paper we review the published literature on patterns of abundance and aggregation of macroparasites in wildlife host populations. We base this survey on quantitative analyses of mean burden and a number of measures of the degree of aggregation of parasite burdens between hosts. All major parasite and vertebrate host taxa were represented in the database. Mean parasite burden was found to be log-normally distributed, indicating that all parasite burdens are regulated to some degree. In addition, all but one of the parasitic infections were aggregated with respect to their hosts, and the relationship between log mean parasite burden and log variance was found to be very strong (R2= 0·87). That is, for a given mean parasite burden there are constraints on the degree of variation in individual host burdens. The aggregated nature of the parasitic infections is also apparent from other measures of the degree of aggregation: prevalence – mean relationships, and the negative binomial parameter,k. Using a relatively new technique for parasitological infection data – tree-based models, as well as traditional linear models – a number of the parasitic infections was found to be associated with systematically lower or higher parasite burdens. Possible biological explanations for these and other patterns are proposed.

The helminths in the gut of perch (Perca fluviatilis L.) in a small oligotrophic lake in southern Norway

A total of 311 perch were examined for gut parasites during the period from April 1972 to December 1973. Four different metazoan parasites were found; Proteocephalus percae (Müller, 1780), Bunodera luciopercae (Müller, 1776), Acanthocephalus lucii Müller, 1776 and Camallanus lacustris Zoega, 1776. B. luciopercae and P. percae exhibited similar seasonal cycles in appearance and abundance. They were both absent from the fish population during June/July. A. lucii and C. lacustris on the other hand had a peak in infection intensity and incidence during the summer and autumn months. From September/October one year to May/June the following year B. luciopercae was the dominating parasite species showing the highest incidence (approximately 95%) and intensity (a mean of about 25 parasites per infected fish). When 2 times 2 contingency tests were applied on the material from this period a significant negative correlation between the presence of P. percae and A. lucii could be pointed out while there was no correlation between the presence of any of the other 3 parasite species.