Reaction of the mussel Mytilus galloprovincialis (Bivalvia) to Eugymnanthea inquilina (Cnidaria) and Urastoma cyprinae (Turbellaria) concurrent infestation

In total 480 individuals of Mytilus galloprovincialis were sampled monthly from October 2009 to September 2010, at the shellfish farm in the Mali Ston Bay, south Adriatic Sea (Croatia) in order to assess the extent of pathology imposed by two parasites, Eugymnanthea inquilina (Cnidaria) and Urastoma cyprinae (Turbellaria). Although a deteriorating impact on host reproduction or condition index was lacking, we evidenced ultrastructural and functional alteration in host cells at the attachment site. Ultrastructural changes included hemocytic encapsulation of the turbellarian and cell desquamation in medusoid infestation. Caspase positive reaction inferred by immunohistochemistry (IHC) was triggered in cases of turbellarian infestation, in contrast with hydroids, suggesting that the former exhibits more complex host-parasite interaction, reflected in the persistent attempts of the parasite to survive bivalve reaction. We have evidenced that both organisms trigger specific host reaction that although not costly in terms of host reproductive cycle or growth, results in mild tissue destruction and hemocyte activation. A lower degree of tissue reaction was observed in cases of hydroid infestation, compared to turbellarian.     

Impact of Ligula intestinalis (L.1758) (Cestode), on the growth of Barbus setivimensis (Cyprinidae) in a lake system in Algeria

The Algerian freshwater fish fauna is mainly represented by the Cyprinidae family, in particular, the genus Barbus. This is represented only by natural populations of the subgenus Barbus. The systematic, based mainly on the methods of biometrics, is quite different from one author to another. However, two nominal species are usually cited: Barbus callensis (Valenciennes, 1842), which is limited to the region of El Kala (eastern Algeria) and Barbus setivimensis (Valenciennes, 1842) in other parts of the North. During the ecological study of this fauna, many individuals were found infested with the tapeworm Ligula intestinalis (Linné, 1758), which led us to study the effect of this parasite on B. setivimensis using the ecological parasites' index (prevalence, abundance and parasite intensity) and to focus on the impact of the parasite on the growth of fish. Tapeworm L. intestinalis presents a wide geographical distribution and a complex lifecycle to multiple hosts: the cycle starts in the body of birds. The life expectancy in the major host is a maximum of 5 days, but in this time, they will lay a multitude of eggs. These eggs are passed into water via the faeces of the bird. Once in the aquatic medium, they hatch and are eaten by a wide range of copepod zooplankton (first intermediate host). The cycle continues when fish (second intermediate host) ingests the copepod. The worm then burrows through the gut wall and continues to develop in the fish's body cavity. The cycle is then complete when the bird (final host) eats the tapeworm-hosting fish. We studied the effects of diet, the hosting period, the habitat on the prevalence, abundance and intensity of the parasitic larvae plerocercoid L. intestinalis and the parasiting effect on the Cyprinids fishs of the genus Barbus in the Keddara dam (Boumerdes, Algeria) during one year. Although L. intestinalis was recorded in several host fish, the available data on the parameters of parasitism are limited and no studies are reported on B. setivimensis. In this study, a total of 613 individuals were sampled and checked on the presence of L. intestinalis plerocercoid stages. Only 64 were infested. The value of the prevalence was 10.44% and the average intensity was 1.89 parasites (average two parasites per infested fish). The infection rate is high during the autumn and low during the spring season. The latter corresponds with the breeding period.     

Changes in the electrophoretic profiles of gill mucus proteases of the eastern oyster Crassostrea virginica in response to infection by the turbellarian Urastoma cyprinae

Urastoma cyprinae occurs on the gills of various bivalves species, including the eastern oyster Crassostrea virginica. While the worm is known to cause severe gill disruption in mussels, no evidence of this nature has been described for oysters. Nonetheless, high levels of U. cyprinae have been reported in oysters, which may, in turn, reduce the oyster's overall condition. U. cyprinae is strongly attracted to oyster gill mucus, which is suggested to play an active role in the worm's feeding activities. Furthermore, host mucus contains many active components, including proteases, which have been suggested to play a defensive role against invading organisms. It follows, therefore, that some of the interactions between U. cyprinae and oysters take place in host gill mucus. Studies were undertaken to determine whether the presence of U. cyprinae altered the electrophoretic profiles of oyster gill mucus, using proteases as indicators. Findings reveal that oyster gill mucus contains three proteases, a putative acid protease at 96 kDa, a zinc metalloprotease at 64 kDa, and a serine protease at 33 kDa. Results based on experiments using mucus preparations extracted from infected and noninfected oysters, along with those using lyophilized mucus incubated with live U. cyprinae, confirm that the presence of U. cyprinae alters the protease composition of gill mucus. The present data demonstrate that both U. cyprinae and host gill mucus actively secrete proteases. While the precise roles of these enzymes still need to be defined, one of their functions may be associated with digestion-related activities induced by the worm.     

Infections by helminth parasites in "puyenes", Galaxias maculatus (Galaxiidae, Salmoniformes), from Southern Argentina with special reference to Tylodelphys barilochensis (Digenea, Platyhelminthes).

The occurrence of Tylodelphys barilochensis, Acanthostomoides apophalliformis, Contracaecum sp. and Camallanus corderoi infecting Galaxias maculatus ("puyenes") was quantified for the first time in Lake Nahuel Huapi, southern Argentina. T. barilochensis was recorded in this lake for the first time. The role of G. maculatus population in transmission of parasites to the salmonids is more important for Contracaecum sp. (prevalence 14-34%) and A. apophalliformis (prevalence 30-54%) than for C. corderoi (prevalence 6-8%). The absence of Diphyllobothrium spp. in samples shows that the G. maculatus population does not play any role in the life cycles of these important zoonotic parasites. The sex of the host had no effect on T. barilochensis abundance. Statistical differences in T. barilochensis abundance between "puyenes" of the same size class between sampling stations and positive correlation between prevalence of infected snails and T. barilochensis abundance in fish suggest that different stocks have been sampled. Factors influencing T. barilochensis abundance are discussed.     

Altered trophic pathway and parasitism in a native predator (Lepomis gibbosus) feeding on introduced prey (Dreissena polymorpha)

Populations of invasive species tend to have fewer parasites in their introduced ranges than in their native ranges and are also thought to have fewer parasites than native prey. This ‘release’ from parasites has unstudied implications for native predators feeding on exotic prey. In particular, shifts from native to exotic prey should reduce levels of trophically transmitted parasites. We tested this hypothesis in native populations of pumpkinseed sunfish (Lepomis gibbosus) in Lake Opinicon, where fish stomach contents were studied intensively in the 1970s, prior to the appearance of exotic zebra mussels (Dreissena polymorpha) in the mid-1990s. Zebra mussels were common in stomachs of present-day pumpkinseeds, and stable isotopes of carbon and nitrogen confirmed their importance in long-term diets. Because historical parasite data were not available in Lake Opinicon, we also surveyed stomach contents and parasites in pumpkinseed in both Lake Opinicon and an ecologically similar, neighboring lake where zebra mussels were absent. Stomach contents of pumpkinseed in the companion lake did not differ from those of pre-invasion fish from Lake Opinicon. The companion lake, therefore, served as a surrogate “pre-invasion” reference to assess effects of zebra mussel consumption on parasites in pumpkinseed. Trophically transmitted parasites were less species-rich and abundant in Lake Opinicon, where fish fed on zebra mussels, although factors other than zebra mussel consumption may contribute to these differences. Predation on zebra mussels has clearly contributed to a novel trophic coupling between littoral and pelagic food webs in Lake Opinicon.     

Impact of a caged-trout farm on parasites of Galaxias maculatus in Lake Moreno, southern Argentina

The present study was conducted to determine the impact of a caged-trout farm on the helminth parasites of the wild fish puyen chico (Galaxias maculatus) in Lake Moreno, southern Argentina. Samples of water, fish (G. maculatus), and snails (Heleobia hatcheri) were taken at 4 sampling stations in January 2001. Wild fish were parasitized by 8 helminth species, all of which are endemic in the region; therefore, the farm did not introduce any helminth parasite to G. maculatus. Fish captured near the farm were not infected by the digenean Steganoderma szidati, whereas the abundance of the digenean Acanthostomoides apophalliformis in these fish was significantly lower than that in fish captured away from the farm. This lower abundance may be explained by the absence in this area of the snail H. hatcheri, the parasite's first intermediate host, because of the effect of sediments and ammonium produced by the farm. To our knowledge, this is the first study in the Americas linking fish-farm pollution to helminth parasites in wild fish.     

The impact of the egg parasitoid Uscana lariophaga on Callosobruchus maculatus populations and the damage to cowpea in a traditional storage system

In West Africa, Uscana lariophaga (Hymenoptera: Trichogrammatidae) parasitizes the eggs of Callosobruchus maculatus (Coleoptera: Bruchidae), an important pest of stored cowpea. The impact of the egg parasitoid on pest populations was evaluated in clay pots used in traditional storage in Niger. At the beginning of the storage period cowpeas were infested with different densities of larval instars and adults of C. maculatus and inoculated with one density of U. lariophaga. The higher the initial densities of C. maculatus, the better the egg parasitoid was able to establish itself and to control the population of C. maculatus, limiting the damage to cowpea. After three months of storage, the egg parasitoid significantly reduced the number of C. maculatus adults by 68 at the lowest and 86 percent at the highest initial density of the beetle; the percentage of damaged beans was reduced by 13 and 19% respectively.     

The host—parasite relationship of two copepod species and two fish species

A total of 2494 Menidia beryllina and 717 M. peninsulae (Atherinidae) were examined from the Pensacola Bay area for parasitic copepods. M. peninsulae was infested with Bomolochus concinnus (Bomolochidae) and Ergasilus marticatus (Ergasilidae) and had incidences (and intensities) of 12.3% (1.6) and 4.2% (1.3), respectively. Only seven M. peninsulae were infested with both species of parasites. M. beryllina was infested only with E. manicatus and showed different incidences (and intensities) in two areas: Mulatto Bayou, 13.2% (1.9); Catfish Basin, 53.0% (2.3). Fishes with parasites were significantly longer than fishes without parasites and the case of increasing number of parasites with increasing fish length was reinforced. B. concinnus is a warm water parasite on M. peninsulae while E. manicatus acts as a cold water parasite on M. peninsulae and a warm water parasite on M. beryllina . The parasites tended to be overdispersed on their hosts but at the same time showed evidence of negative intraspecific associations within a host. These data suggest intraspecific avoidance by the parasite but active acquisition by the host.     

The influence of climate on the distribution of monogeneans of anurans in Nigeria

Investigations undertaken on the monogeneans of amphibians in Nigeria have shown that host ecology has an influence on the distribution of these monogeneans. Amphibians from humid environments of the rainforest, a freshwater swamp and mangrove harboured no monogeneans, whereas those occurring in drier conditions in the savannah-mosaic and guinea savannah yielded five species of polystomatid parasites: Polystoma prudhoei from Bufo regularis, Polystoma galamensis from Rana galamensis, Eupolystoma alluaudi from Bufo regularis and Bufo maculatus, and two unidentified Polystoma species from Bufo regularis and Ptychadena oxyrynchus, respectively. Some of these monogeneans appear to have reproduction cycles which are synchronized with those of the hosts. The prevalence of E. alluaudi in Bufo spp. caught in New Bussa (68.4% in B. regularis and 82.3% in B. maculatus) were higher than those reported for this parasite in other locations in West Africa and for Eupolystoma anterorchis in Bufo pardalis from the Cape Flats of South Africa.     

河蚌血细胞对细菌趋化移动的初步研究

采用改进的毛细管法 ,研究了圆背角无齿蚌 (Anodontawoodianapacifica)和三角帆蚌 (Hyriopsiscum ingii)两种淡水河蚌离体血细胞对两种水体中常见病原细菌的趋化移动作用 ,及血清对其的影响。结果显示 ,两种河蚌的离体血细胞对细菌都具有趋化移动作用 ,产生趋化移动的血细胞数量都显著高于无细菌的对照组 (P <0 0 5 )。在有血清时 ,血细胞对荧光极毛杆菌 (Pseudomonasfluorescens)的趋化移动活性略高于肠型点状气单孢菌 (Aeromonaspunctataf.intestinalis) ,圆背角无齿蚌离体血细胞的趋化移动能力显著高于三角帆蚌 (P <0 0 5 )。血清对河蚌离体血细胞的趋化移动作用有显著的促进作用 (P <0 0 5 )。     

Prevalence and abundance of Ixodes pacificus immatures (Acari: Ixodidae) infesting western fence lizards (Sceloporus occidentalis) in northern California: temporal trends and environmental correlates.

The prevalence and abundance of immature Ixodes pacificus ticks on western fence lizards (Sceloporus occidentalis) were examined in relation to time of year, host attributes (i.e., age, gender, and presence or absence of blood parasites), and 5 environmental characteristics, including topographic exposure and ground cover substrate, over a 2-year period in northern California. Lizards were infested with subadult ticks from early March until late July or early August, with peak median numbers of larvae and nymphs recorded in late April and early May of both years. Peak larval and nymphal abundances differed between years. The overall ratio of larvae to nymphs on adult male lizards was low, ranging from 0.80 in 1999 to 2.41 in 2000. Such intensive feeding of nymphs versus larvae on these lizards, which are reservoir-incompetent for Borrelia burgdorferi spirochetes, may explain previous observations of decreasing spirochetal infection prevalence from the nymphal to adult stage in northwestern California. Adult male lizards were more likely to be infested with nymphs and harbored greater abundances of larvae and nymphs than adult females. Lizards uninfected with blood parasites had more nymphs than infected lizards. The measured environmental characteristics could explain only a small percentage of the total variation observed in larval prevalence (22%) and in larval and nymphal abundance (12 and 3%, respectively).     

In vitro effect of nitazoxanide against Entamoeba histolytica,Giardia intestinalis and Trichomonas vaginalis trophozoites

Nitazoxanide, a 5-nitrothiazolyl derivative, is effective in the treatment of a broad range of parasitic infections. In vitro, it is active against several protozoa, including Cryptosporidium parvum, Blastocystis hominis, and Giardia intestinalis. The objective of this study was to determine the in vitro effect of nitazoxanide on the growth and morphology of three anaerobic protozoa (Entamoeba histolytica, Giardia intestinalis, and Trichomonas vaginalis) and to compare these effects with those of metronidazole and albendazole. A subculture method was used to determine the concentrations required to inhibit growth by 50% or 90% (IC50 and IC90,). Nitazoxanide exhibited IC50, and IC90 values of 0.017 and 0.776 microg/ml respectively, against E. histolytica, 0.004 and 0.067 microg/ml against G. intestinalis, and 0.034 and 2.04 6 microg/ml against T. vaginalis. Based on the IC90 values, nitazoxanide was more toxic than metronidazole and albendazole against E. histolytica; albendazole and nitazoxanide were more toxic than metronidazole against G. intestinalis; and metronidazole was the most toxic drug against T. vaginalis. The effects of nitazoxanide on trophozoite ultrastructure of all three parasites included cell swelling and distorted cell shape, a redistribution of vacuoles, plasma membrane damage, and the formation of extensive empty areas in the cytoplasm of the protozoa.     

Parasitism in species of Bathymodiolus (Bivalvia: Mytilidae) mussels from deep-sea seep and hydrothermal vents

Bivalve species, especially mussels, are biomass dominants in many deep-sea chemosynthetic ecosystems. As in shallow-water environments, parasites are likely to be important factors in the population dynamics of bivalve communities in chemosynthetic ecosystems, but there has been little study of parasitism in deep-sea seep or vent molluscs. In this study, parasite types, diversity, prevalence, infection density and non-infectious indicators of stress or disease as related to host age, reproductive condition, and endosymbiont density were assessed in mussels (Bathymodiolus heckerae) from 2 seep sites and mussels (B. puteoserpentis) from 2 vent sites. We identified 10 microbial or parasitic agents in histological sections. Parasite types included 3 viral-like gut inclusions, 2 rickettsia-like gill inclusions, a rickettsia-like mantle inclusion, a bacterial gill-rosette, a chlamydia-like gut inclusion, gill-dwelling ciliates, and an unidentified inclusion in gut tissues. Parasite species richness was greater in seep mussels than in vent mussels, with the seep mussels possessing 9 types of parasites compared to 2 in the vent mussels. One of the viral-like inclusions infecting the seep mussel B. heckerae was pathogenic, causing lysis of the digestive tubules. The prevalence and intensity of infection by this pathogen were greater in hosts with shell lengths less than 100 mm. Mussels from all 4 sites also exhibited intense infiltration of tissues and blood spaces by enlarged hemocytes. Hemocytic infiltration (hemocytosis) showed variable degrees of severity that were not associated with other host factors examined.     

THE INFESTATION OF MYTILUS EDULIS LINNAEUS BY POLYDORA CILIATA (JOHNSTON) IN THE CONWY ESTUARY, NORTH WALES

The incidence of the shell-boring parasite Polydora ciliatain Mytilus edulis from the Conwy estuary, North Wales is described.Amongst mussels >40 mm in shell length both the occurrenceand abundance of P. ciliata increased steeply with host size.Infestation was highest amongst mussels near the mouth of theestuary where around 60–65% of the population was parasitized;no systematic relationship between the incidence of P. ciliataand tidal elevation was observed. Mussel condition was negativelycorrelated with the degree of infestation. Moderately and heavilyinfested mussels, however, never accounted for more than ca.10% of this population and the overall detrimental effects ofP. ciliata on growth and production is thus probably quite small.Whilst heavily infested mussels were evidently more vulnerableto predation, the shore crab, Carcinus maenas, selected smaller,non-infested mussels whenever these were available. No obviousrelationships were found between the presence of P. ciliataand the incidence of either pearls or pea crabs. (Received 14 January 1991; accepted 2 April 1991)     

Mytilus edulis chilensis infested with Coccomyxa parasitica (Chlorococcales, Coccomyxaceae)

The association between the green alga Coccomyxa parasitica (Chlorococcales)and the mussel Mytilus edulis chilensis at Goose Green, Falkland Islandsis reported. C. parasitica occurred within the soft tissueswith an overall infestation rate of 16%. The highest levelsof infestation (23%) occurred in individuals from the middleof the main mussel bed, with considerably lower levels of infestation inthe upper and lower regions (<1% and 5% respectively). Noconsistent seasonal pattern in infestation rate was detectedbetween September 1993 and February 1996. C. parasitica wasmost commonly observed in tissues located in the posterior territoryof the host, in areas most directly exposed to light. Tissuesof infested mussels were rather watery and translucent and theadductor muscle appeared weak and stringy. During the summermonths when Falkland mussels are in peak reproductive condition,dry flesh weight of infested mussels was significantly lowerthan non–infected mussels of comparable size suggestingthat infestation by C. parasitica may reduce reproductive output.However it is uncertain whether poor condition of the host isdue to the presence of the parasitic alga or whether C. parasiticainfests only those mussels that are already in poor condition. ¹ Present address: 3, St Marys Walk, PO Box 530, Stanley, Falkland Islands (Received 10 June 1998; accepted 8 September 1998)     

Infestation of the blue mussel Mytilus galloprovincialis by the copepod Pseudomyicola spinosus and its relation to size,density, and condition index of the host

The copepod Pseudomyicola spinosus infests marine mussels and other commercial bivalve species. There is a lack of information on the infestation process and on its relationship to size, density, and health of the host. To obtain this information, an infestation study of the copepod in Mytilus galloprovincialis in field conditions was carried out. Results showed that the intensity of infestation is closely related to host size [F((2,810))=198.33; p<0.001], but not to density [F((2,810))=0.96; p<0.38]. After an initial colonization of the host by the infested copepodite stages, an equilibrium between the intensity of the infestation and host size is maintained; mean intensity in small mussels was 1.57, in medium mussels it was 4.23, and in large mussels it was 9.86. Adult stages were observed after a period of 30 days, and ovigerous females were observed after a period of 45 days. Copepods may be found on the branches and mantle (89.5%) and inside the digestive tract (10.5%); in this last case and at the end of the study period some histological disorders were found such as obstruction of the intestine, rupture of the digestive epithelia, and encapsulations around digestive tissues. Most infested mussels showed the lowest meat weight in relation to shell weight; however, the reproductive stage may affect this observation.     

Further information on fish parasites from Lake Trasimeno. II. Observations on the population of Scardinius erythrophthalmus L

An investigation was carried out to identify the actual state of parasitism in the Scardinius erythrophthalmus L. population of Trasimeno lake (Umbria, Italy). Seasonal samples of fishes were taken in different points of the litoral and pelagic zones. The parasites found, together with the somatometric values and the characteristics of their localizations are reported. It has been found: a high number of infested specimens; eleven species of parasites, of which five were not yet known to be in the lake; frequency variations of certain species. The species of parasites observed are distributed in the Paleartic region. The five species, whose presence was not known in the lake, are considered to be allochtonous. The organs most frequently involved were, in descending order, the gills, the ureters, the gonads, the intestinal and mesenteric serous membranes, the liver. The most marked histologic alterations and reactions were observed as a consequence of Ergasilus sieboldi Nord. action and, in several cases, with the presence of Ligula intestinalis L. larvae.     

Parasite communities of the Schlei Fjord (Baltic coast of northern Germany)

The parasite faunas of snails, mussels, crustaceans and small-sized fishes were investigated over a period of six months in the Schlei fjord, on the Baltic coast of Schleswig-Holstein. Two sites differing in salinities were compared: Missunde with 5–9 ‰ and Olpenitz with 12–20 ‰. Prevalences, number of host-parasite combinations, numbers of core and secondary species were generally higher in Olpenitz than in Missunde. In the latter site, only prevalences of cestodans in planktic copepods and the number of rare species were apparent. Specificity of parasites was relatively high in snails, mussels and fishes, but lower in benthic crustaceans. Parasites may survive in an extreme environment like brackish water by means of special strategies which differ from those acquired in the marine milieu: suspension of specificity, adaptation to hosts which are genuine brackish water species, extension of host spectra, and shortening of life-cycles. Although the parasite communities of the Schlei fjord were primarily influenced by the prevailing salinities, the influence of other factors, e.g. environmental stress, was also confirmed. Whereas generally low prevalences in Missunde may contradict Thienemann’s biocoenotic rule, planktic parasites infested their hosts often at higher rates than in Olpenitz. This phenomenon is explained by the poorer environmental condition of the benthal zone in Missunde compared to that of the pelagial or the benthal zones of Olpenitz.     

Efficacy of ivermectin (Ivomec) against intestinal capulariosis in falcons

52 captive falcons out of 3,988 (1.3 %) raptors microscopically examined for intestinal parasites in the Middle East proved infested with hairworms (capillariid parasites). 26 of these (50 %) showed concurrent parasitoses. In the group of 26 falcons diagnosed with capillariosis as sole infestation (50 %) compatible clinical signs such as anorexia, weight loss, weakness, dyspnoea, regurgitation of food and blood, diarrhoea and dark tarry faeces, were recorded. These birds were treated intramuscularly with ivermectin at doses of 2 mg/kg. In fecal samples examined 10-15 days later, the eggs of capillariid parasites had disappeared, in association with complete clinical recovery.     

A possible evolutionary lag in the relationship between freshwater mussels and European bitterling

The coevolutionary dynamics between European bitterling Rhodeus amarus and freshwater unionid mussels, which the former parasitize by laying eggs on their gills, were tested. In a series of experiments fish preferences and mussel responses were compared in parasites and hosts of recent (Europe) and ancient (Asia) sympatry. Rhodeus amarus readily oviposited on the gills of all mussel species tested. Fish that laid their eggs on the gills of Asian Anodonta woodiana, however, suffered a dramatic reduction in reproductive success compared to fish that oviposited on the gills of European mussels: Unio pictorum , Unio tumidus , Anodonta anatina and Anodonta cygnea . This difference was the result of egg ejection behaviour by mussels rather than the unsuitability of the internal gill environment for European bitterling embryo development. The ejection response of mussels with a long sympatry with European bitterling was considerably more pronounced than that of mussels with a substantially shorter sympatry. The data support a coevolutionary arms race between bitterling and mussels and point to an evolutionary lag in the relationship between R. amarus and its European mussel hosts.