Acanthocephalus Anguillae Research Articles

Host-parasite interface between Asellus aquaticus (Isopoda) and larvae of Acanthocephalus anguillae (Acanthocephala)

The present study describes the ultrastructure of the interface between naturally infected isopods, Asellus aquaticus (L.), from the River Brenta (northern Italy) and larvae of Acanthocephalus anguillae (Muller, 1780) Luhe, 1911. A fully developed larva of this helminth occupies the host’s hemocoel and induces displacement of its internal organs. A transparent acellular envelope ranging in thickness from 1.1 to 1.6 µm covers each A. anguillae larva within the hemocoel of the crustacean. This envelope establishes intimate contact with the internal organs and hemocytes of the host. Intact isopod hemocytes, as well as cells in varying degrees of degeneration, were observed mainly on the outermost edge of the envelope of A. anguillae. No melanised acanthocephalan larvae were seen within the hemocoel.

Copulation of Acanthocephalus anguillae (Acanthocephala).

A total of 114 specimens of brown trout, Salmo trutta Linnaeus, 1758, was sampled by electrofishing between October 1998 and July 1999 from the Ceresone stream (North of Padua, Italy). Over 63% of fish were infected with three species of helminth: a tapeworm, Cyathocephalus truncatus (Pallas, 1781), and two acanthocephalan species, Echinorhynchus truttae (Schrank, 1788) and Acanthocephalus anguillae (Muller 1780). On three occasions, in the fore-gut of three brown trout, three pairs of A. anguillae were found in copula. In all three cases, the male's bursa was fully extruded and firmly attached to the posterior region of the female. Cement was found inside the bursa suggesting that insemination had probably occurred. Eight female A. anguillae recovered in five other infected trout had attached copulatory caps.

METAZOAN PARASITES OF PIKE (ESOX LUCIUS L.) FROM LAKE ULUABAT, TURKEY

In this study, metazoan parasites of pike (Esox lucius L.) from Lake Uluabat were investigated monthly from January 1993 to January 1994. Parasites belonging to six species were recorded for 133 pike hosts: Argulus foliaceus, Tetraonchus monenteron, Rhipidocotyle fennica, Diplodiscus subclavatus, Raphidascaris acus, and Acanthocephalus anguillae, of which only two specimens of A. foliaceus were found in the gills of one host fish, and a single specimen of A. anguillae and two specimens of D. subclavatus in the intestine of another. Tetraonchus monenteron, R. fennica, and R. acus were the dominant parasite species found in the pike. Tetraonchus monenteron was the most prevalent species found in fish of all sizes during the year of the study. Rhipidocotyle fennica infection rate was highest during summer and autumn and minimal during winter and early spring, with larger pike having more parasites than smaller host pike. The third dominant parasite, R. acus, produced two generations per season, with peaks in...

METAZOAN PARASITES OF PIKE (ESOX LUCIUS L.) FROM LAKE ULUABAT, TURKEY

In this study, metazoan parasites of pike (Esox lucius L.) from Lake Uluabat were investigated monthly from January 1993 to January 1994. Parasites belonging to six species were recorded for 133 pike hosts: Argulus foliaceus, Tetraonchus monenteron, Rhipidocotyle fennica, Diplodiscus subclavatus, Raphidascaris acus, and Acanthocephalus anguillae, of which only two specimens of A. foliaceus were found in the gills of one host fish, and a single specimen of A. anguillae and two specimens of D. subclavatus in the intestine of another. Tetraonchus monenteron, R. fennica, and R. acus were the dominant parasite species found in the pike. Tetraonchus monenteron was the most prevalent species found in fish of all sizes during the year of the study. Rhipidocotyle fennica infection rate was highest during summer and autumn and minimal during winter and early spring, with larger pike having more parasites than smaller host pike. The third dominant parasite, R. acus, produced two generations per season, with peaks in...

Heavy metals concentrations in acanthocephalans parasites compared to their fish host

A number of authors have demonstrated that heavy metal concentrations in intestinal Helminths are higher than those found in the tissues of their final hosts. In this work, Pb and Cr concentrations in the Acanthocephalan Acanthocephalus anguillae were measured by means of electrothermal atomic absorption spectrometry. The metal concentrations measured in the whole body of Acanthocephalans were compared to those in the liver of their fish hosts ( Leuciscus cephalus) sampled in the Lambro river (Northern Italy). The results show higher concentrations of Pb and Cr in the parasites, respectively ∼ 200 times and ∼60 times higher than that of the host liver. These results corroborate the usefulness of parasites in the monitoring of biologically available metal concentrations in aquatic ecosystems that are non severely polluted.

Parasite fauna of the tench, Tinca tinca (L.) from selected lakes of the north-western regions of Poland

In the tench collected from three lakes of the north-western region of Poland, namely: lake Ińsko, lake Mielno, and lake Woświn, a total of 20 parasite species was recorded. Representatives of the following species were commonly found: Ichthyophthirius multifiliis, Dactylogyrus triappendixis, Asymphylodora tincae and Ergasilus sieboldi (the prevalence ranged from 34.37 to 65.62%). Trypanosoma sp., Myxobolus ellipsoides, Trichodina sp., Trichodinella epizootica, metacercariae of Tylodelphys clavata and Skrjabillanus tincae were recorded relatively often (18.75-28.12%). The presence of Thelohanellus pyriformis, Caryophyllaeus laticeps, egss of Sanguinicola sp., metacercariae of Diplostomum sp., and larvae of Raphidascaris acus (9.37% of infection) were recorded less frequently. The remaining parasites, namely: Philomerta ovata, Piscicola geometra, Acanthocephalus anguillae, A. lucii, and Argulus foliaceus occurred as single specimens (3.12% of infection). Protozoans T. epizootica and nematodes P. ovata were recorded for the first time in the tench in Poland, whereas 18 species of parasites have not been noted yet in the north-western region of the country.

Proteolytic Enzymes of Pomphorhynchus laevis and in Three Other Acanthocephalan Species

Cystacanths and adults of the acanthocephalan Pomphorhynchus laevis were found to release proteolytic enzymes during in vitro culture. Culture media in which cystacanths had been kept contained a trypsinlike collagenolytic proteinase exhibiting a molecular mass of 29 kDa on gelatin substrate gel electrophoresis and a pH optimum at pH 9.0. Samples of adults possessed a trypsinlike collagenolytic proteinase with a molecular mass of 26 kDa and showed a pH optimum at 9.0. Leucine aminopeptidase activity was also present in culture media of adults. An apparent molecular mass of 92 kDa and a pH optimum at pH 8.5 were determined for this proteolytic enzyme. It was concluded that the trypsinlike proteinases of both stages were necessary for the complete and quick perforation of the fishes' intestinal wall, whereas the leucine aminopeptidase seemed to have a nutritional function in the terminal stages of protein hydrolysis at the surface of the worm's body wall. Cystacanths of 3 other species of fish-parasitizing Acanthocephala (Acanthocephalus anguillae, Acanthocephalus lucii, Paratenuisentis ambiguus) did not show any histolytic activity.

Occurrence of larvalacanthocephalus anguillae(acanthocephala) in theasellus aquaticus(crustacea, isopoda) from the river brenta

Abstract A total of 440 specimens of Asellus aquaticus were collected from the River Brenta (northern Italy) in a single sampling in August 1992, and examined for larval helminth parasites. From the hemocoels of 14 (3.1%) individuals of A. aquaticus, 17 acanthocephalan larvae were removed: of these 15 were well‐developed cystacanths of Acanthocephalus anguillae (a new geographical recording for cystacanth); not more than two larvae were found in a single host. The sex‐ratio among the parasitized isopods was approximately 1:1. In more than 64% of infected A. aquaticus, the integumental pigmentation was darker than that of non‐parasitized individuals. Infected isopods were never observed in amplexus, and one parasitized female specimen carried 50 eggs in its brood pouch. In hosts with well‐developed cystacanths, the displacement of isopod internal organs, such as the alimentary canal, was observed.

Potential interactions between Acanthocephalus anguillae and Pomphorhynchus laevis in their natural hosts chub, Leuciscus cephalus and the European eel, Anguilla anguilla

Chub and eels were experimentally infected via intermediate hosts harbouring cystacanths, with Pomphorhynchus laevis alone, or Acanthocephalus anguillae alone, or simultaneously with mixtures of both species in varying proportions, and sampled at 7, 56 or 112 days post-infection. Examination of chub revealed that both species showed low establishment and growth rates, differing markedly from British field data, where chub is apparently one of the most important hosts, and preventing further meaningful experiments. Both species showed higher establishment rates in eels, but A. anguillae both grew faster and matured to a greater extent than P. laevis, reflecting field data. No evidence of any interactions, competitive or otherwise, was found in the mixed infections in eels at low or high infection levels. The results were interpreted with regard to British field data and current theories of the role of interspecific competition in structuring fish helminth communities.

Acanthocephala in fish from the Bothnian Bay, Finland

A sample of 7266 fish from 31 species was obtained from the north‐eastern Bothnian Bay, Baltic Sea, from 1975 to 1982. Twenty‐six fish species were found to be infected with seven acanthocephalan species identified as Echinorhynchus salmonis, E. bothniensis, E. borealis, E. gadi, Acanthocephalus anguillae, A. lucii and Neoechinorhynchus rutili. Acanthocephalus lucii was the only acanthocephalan not to attain sexual maturity in at least one species of fish. Fourteen new host records were found for E. bothniensis. A total of 1576 acanthocephalan infections was found; in most cases these were single species infections, but in 108 cases infections of two, and in two cases of three species were observed.The most prominent host‐parasite relationship involved E. salmonis and Coregonus widegreni, where the total of 11 505 worms taken from 1164 fish was roughly ten times the number of any of the other acanthocephalan parasites taken from all its hosts. Echinorhynchus gadi was encountered only in Gadus morhua. The fish of the Bothnian Bay were not considered to offer an important environment for E. gadi, E. borealis or A. lucii. Acanthocephalus anguillae was common only in Leuciscus idus while the range of hosts for N. rutili was found to be broad with 15 of 18 infected fish species being genuine definitive hosts.Larger host fish tended to be more frequently and heavily infected than smaller ones with all acanthocephalan species except for N. rutili. Female fish were usually more heavily infected than males and the frequency distributions of numbers of acanthocephalans per fish were often observed to be overdispersed. The occurrence of non‐acanthocephalan species of helminth in the alimentary tracts of 23 species of fish was recorded during the survey. On the basis of estimates of Berger‐Parker indices, acanthocephalans were considered to be dominant in seven species of fish, cestodes in 12, digeneans in three and nematodes in one host species. Observations were also made on acanthocephalans in lampreys. The relevance of some of the findings for acanthocephalan transmission and adaptation to new environments is discussed briefly.

Discontinuous distributions of the fish acanthocephalans Pomphorhynchm laevis and Acanthocephalus anguillae in Britain and Ireland: an hypothesis

The current distributions of the freshwater fish acanthocephalans Pomphorhynchus laevis and Acanthocephalus anguillae are described and shown to be discontinuous and mutually exclusive, both regionally and locally, in the British Isles. An hypothesis is erected to account for this pattern. It is suggested that as the continental freshwater cyprinids colonized post‐glacial mainland Britain via the eastward‐flowing rivers and the Thames‐Rhine link, they brought with them both species of acanthocephalan. The present, more extensive distribution of P. laevis in the British Isles and Ireland is explained by (1) early formation of a marine strain that colonized the Baltic and North Sea and estuaries of North Sea rivers, (2) later transfers of infected barbel to other English rivers from the R. Thames by man, and (3) transfers to Ireland of infected cyprinids from England by man. Different and restricted availability of preferred definitive and intermediate hosts subsequently resulted in the formation of distinct strains in England and Ireland. The distribution of A. anguillae can be explained by similar anthropogenic influences, but since its definitive and intermediate hosts are more widely available, strain formation has not yet been detected. Competitive interactions between the two parasites in the intestine of the definitive hosts are thought to be responsible for their mutual exclusiveness.

Acanthocephalus anguillae in Intra- and Extraintestinal Positions in Experimentally Infected Juveniles of Goldfish and Carp and in Sticklebacks

In the laboratory fingerlings of goldfish and carp as well as adult sticklebacks (Gasterosteus aculeatus) were infected with the palaeacanthocephalan Acanthocephalus anguillae. The fish were killed from 5 to 90 days later. In goldfish, worms began perforating the intestinal muscularis within the first 5 days postinfection (DPI). From about 50 days they were also found in toto inside the peritoneal cavity where they had become covered by a precipitin-like coat. Disintegrating dead worms always were enclosed by a granuloma consisting mainly of macrophages in different maturation stages. In carp intraperitoneal worms were recorded as early as 10 DPI. They provoked a heavy eosinophilic reaction and degenerated within a few days. In stickleback the recovery rates were very low; only 1 worm of 10 DPI was found just penetrating into the peritoneal cavity. The worms did not reproduce in any of the 3 hosts. However, female worms with copulatory caps were found, indicating that they had been inseminated. It is suggested from these results and from the literature that A. anguillae has a low ability to use paratenic hosts in its life cycle.