The consequences of self-fertilization and outcrossing of the cestode Schistocephalus solidus in its second intermediate host

Parasitology ◽  
2003 ◽  
Vol 126 (4) ◽  
pp. 369-378 ◽  
Author(s):  
M. CHRISTEN ◽  
M. MILINSKI
Keyword(s):  
Intermediate Host ◽  
Gasterosteus Aculeatus ◽  
Life Stage ◽  
Life History Strategy ◽  
Body Cavity ◽  
Infected Fish ◽  
Mixed Mating ◽  
Schistocephalus Solidus ◽  
Self Fertilization ◽  
Second Intermediate Host

Many hermaphroditic parasites reproduce by both cross-fertilization and self-fertilization. To understand the maintenance of such mixed mating systems it is necessary to compare the fitness consequences of the two reproductive modes. This has, however, almost never been done in the context of host–parasite coevolution. Here we show the consequences of outcrossing and selfing in an advanced life-stage of the cestode Schistocephalus solidus, i.e. in its second intermediate host, the three-spined stickleback (Gasterosteus aculeatus). Each juvenile stickleback was simultaneously exposed to 2 experimentally infected copepods, one harbouring outcrossed the other selfed parasites. At 60 days p.i. parasites were removed from the fish's body cavity and, with microsatellite markers, assigned to either outcrossed or selfed origin. Prevalence was not significantly higher in outcrossed parasites. However, those fish that were infected contained significantly more outcrossed than selfed parasites. Thus the probability of a selfed parasite to progress in the life-cycle is reduced in the second intermediate host. Furthermore, we found that even the multiply infected fish increased in weight during the experiment. Nevertheless, total worm weight in multiply infected fish was significantly lower than in singly infected ones, which thus might be a parasite life-history strategy.

Host mortality and variability in epizootics of Schistocephalus solidus infecting the threespine stickleback, Gasterosteus aculeatus

Parasitology ◽  
2010 ◽  
Vol 137 (11) ◽  
pp. 1681-1686 ◽  
Author(s):  
D. C. HEINS ◽  
E. L. BIRDEN ◽  
J. A. BAKER
Keyword(s):  
Gasterosteus Aculeatus ◽  
Infected Fish ◽  
Threespine Stickleback ◽  
Intensity Of Infection ◽  
Host Fish ◽  
Schistocephalus Solidus ◽  
Second Intermediate Host ◽  
Host Mortality ◽  
Abiotic And Biotic Factors ◽  
Host Behaviour

SUMMARYAn analysis of the metrics of Schistocephalus solidus infection of the threespine stickleback, Gasterosteus aculeatus, in Walby Lake, Alaska, showed that an epizootic ended between 1996 and 1998 and another occurred between 1998 and 2003. The end of the first epizootic was associated with a crash in population size of the stickleback, which serves as the second intermediate host. The likely cause of the end of that epizootic is mass mortality of host fish over winter in 1996–1997. The deleterious impact of the parasite on host reproduction and increased host predation associated with parasitic manipulation of host behaviour and morphology to facilitate transmission might also have played a role, along with unknown environmental factors acting on heavily infected fish or fish in poor condition. The second epizootic was linked to relatively high levels of prevalence and mean intensity of infection, but parasite:host mass ratios were quite low at the peak and there were no apparent mass deaths of the host. A number of abiotic and biotic factors are likely to interact to contribute to the occurrence of epizootics in S. solidus, which appear to be unstable and variable. Epizootics appear to depend on particular and, at times, rare sets of circumstances.

The Effect of Schistocephalus Solidus (Cestoda: Pseudophyllidea) On the Foraging and Shoaling Behaviour of Three-Spined Sticklebacks, Gasterosteus Aculeatus

Behaviour ◽  
1995 ◽  
Vol 132 (15-16) ◽  
pp. 1223-1240 ◽  
Author(s):  
Iain Barber ◽  
Felicity A. Huntingford
Keyword(s):  
Experimental Work ◽  
Gasterosteus Aculeatus ◽  
Stomach Contents ◽  
Handling Time ◽  
Body Cavity ◽  
Infected Fish ◽  
The Body ◽  
Large Prey ◽  
Schistocephalus Solidus ◽  
Shoaling Behaviour

AbstractIn this paper we review recent experimental work on the effects of the parasite Schistocephalus solidus (Cestoda: Pseudophyllidea) on the feeding behaviour of three-spined sticklebacks (Gasterosteus aculeatus L.). We also discuss how increased feeding motivation and subsequent altered foraging behaviour may be a mechanism for parasite-associated changes in the shoaling behaviour of infected sticklebacks. The presence of S. solidus plerocercoids in the body cavity constricts the stomach, increases the handling time for large prey and consequently reduces the profitability of such prey for infected fish. This is reflected in a switch in dietary preference from large to small prey in the laboratory and in altered stomach contents and impaired nutrient reserves in the wild. By altering their hosts' nutritional state by direct competition for nutrients from digested food (and possibly indirectly by altering diet and reducing competitive ability) and also by altering the fishes' appearance, such parasites have the potential to alter the costs and benefits involved in joining a shoal of conspecifics. Experimental work on the shoaling decisions of S. solidus-infected sticklebacks supports this hypothesis, and such behavioural modification is discussed in the context of the manipulation hypothesis of parasite transmission.

Life cycles of species of Proteocephalus, parasites of fishes in the Palearctic Region: a review

1999 ◽  
Vol 73 (1) ◽  
pp. 1-19 ◽  
Author(s):  
T. Scholz
Keyword(s):  
Intermediate Host ◽  
Body Cavity ◽  
Life Cycles ◽  
The Body ◽  
Individual Species ◽  
Intermediate Hosts ◽  
Palearctic Region ◽  
Second Intermediate Host ◽  
Planktonic Crustaceans ◽  
Fish Hosts

The life cycles of species of Proteocephalus Weinland, 1858 (Cestoda: Proteocephalidea) parasitizing fishes in the Palearctic Region are reviewed on the basis of literary data and personal experimental observations, with special attention being paid to the development within the intermediate and definitive hosts. Planktonic crustaceans, diaptomid or cyclopid copepods (Copepoda), serve as the only intermediate hosts of all Proteocephalus species considered. A metacestode, or procercoid, develops in the body cavity of these planktonic crustaceans and the definitive host, a fish, becomes infected directly after consuming them. No previous reports of the parenteral location of metacestodes within the second intermediate host as it is in the Nearctic species P. ambloplitis have been recorded. Thus, the life cycles of Proteocephalus tapeworms resemble in their general patterns those of some pseudophyllidean cestodes such as Eubothrium or Bothriocephalus, differing from the latter in the presence of a floating eggs instead of possessing an operculate egg from which a ciliated, freely swimming larva, a coracidium, is liberated. The scolex of Proteocephalus is already formed at the stage of the procercoid within the copepod intermediate host; in this feature, proteocephalideans resemble caryophyllidean rather than pseudophyllidean cestodes. The morphology of procercoids of individual species is described with respect to the possibility of their differentiation and data on the spectrum of intermediate hosts are summarized. Procercoids of most taxa have a cercomer, which does not contain embryonic hooks in contrast to most pseudophyllidean cestodes. The role of invertebrates (alder-fly larvae — Megaloptera) and small prey fishes feeding upon plankton in the transmission of Proteocephalus tapeworms still remains unclear but these hosts are likely to occur in the life cycle. Data on the establishment of procercoids in definitive hosts, morphogenesis of tapeworms within fish hosts, and the length of the prepatent period are still scarce and new observations are needed. Whereas extensive information exists on the development of P. longicollis (syns. P. exiguus and P. neglectus), almost no data are available on the ontogeny of other taxa, in particular those occurring in brackish waters (P. gobiorum, P. tetrastomus). The morphology of P. cernuae and P. osculatus procercoids from experimentally infected intermediate hosts is described for the first time.

Encystment site affects the reproductive strategy of a progenetic trematode in its fish intermediate host: is host spawning an exit for parasite eggs?

Parasitology ◽  
2011 ◽  
Vol 138 (9) ◽  
pp. 1183-1192 ◽  
Author(s):  
KRISTIN K. HERRMANN ◽  
ROBERT POULIN
Keyword(s):  
Life Cycle ◽  
Intermediate Host ◽  
Body Cavity ◽  
Life Cycles ◽  
Temperature Changes ◽  
Fish Spawning ◽  
Second Intermediate Host ◽  
Host Life ◽  
Major Factors ◽  
Fish Hosts

SUMMARYEach transmission event in complex, multi-host life cycles create obstacles selecting for adaptations by trematodes. One such adaptation is life cycle abbreviation through progenesis, in which the trematode precociously matures and reproduces within the second intermediate host. Progenesis eliminates the need for the definitive host and increases the chance of life cycle completion. However, progenetic individuals face egg-dispersal challenges associated with reproducing within metacercarial cysts in the tissues or body cavity of the second intermediate host. Most progenetic species await host death for their eggs to be released into the environment. The present study investigated temporal variation of progenesis in Stegodexamene anguillae in one of its second intermediate fish hosts and the effect of the fish's reproductive cycle on progenesis. The study involved monthly sampling over 13 months at one locality. A greater proportion of individuals became progenetic in the gonads of female fish hosts. Additionally, progenesis of worms in the gonads was correlated with seasonal daylight and temperature changes, major factors controlling fish reproduction. Host spawning events are likely to be an avenue of egg dispersal for this progenetic species, with the adoption of progenesis being conditional on whether or not the parasite can benefit from fish spawning.

STUDIES ON CESTODES OF THE GENUS TRIAENOPHORUS FROM FISH OF LESSER SLAVE LAKE, ALBERTA: IV. THE LIFE OF TRIAENOPHORUS CRASSUS FOREL IN THE SECOND INTERMEDIATE HOST

1945 ◽  
Vol 23d (4) ◽  
pp. 105-115 ◽  
Author(s):  
Richard B. Miller
Keyword(s):  
Intermediate Host ◽  
Lake Trout ◽  
Body Cavity ◽  
The Body ◽  
Coregonus Clupeaformis ◽  
Alternative Hosts ◽  
Pyloric Caeca ◽  
Drying Up ◽  
Second Intermediate Host

The plerocercoids of Triaenophorus crassus encyst normally in the flesh of fishes of the genus Leucichthys; the whitefishes, Coregonus clupeaformis and Prosopium oregonium, are common alternative hosts in Lesser Slave Lake. Elsewhere lake trout, Cristivomer namaycush, and possibly the inconnu, Stenodus leucichthys, may occasionally serve as hosts.The procercoids arrive in the stomach of their second intermediate host while in the body cavity of Cyclops bicuspidatus. When they are liberated by digestion, the majority apparently enter pyloric caeca, penetrate these, cross the body cavity, and enter the flesh, where encystment as the plerocercoid takes place. The evidence for these movements is only partial. The plerocercoids encyst in the flesh in July each year. They remain three or four years and then disappear by drying up or being reduced to small calcareous nodules.The number of plerocercoids per fish increases with the age of the fish up to five or six years.

Infections of the three-spined stickleback, Gasterosteus aculeatus L., with the plerocercoid larvae of Schistocephalus solidus (Müller, 1776), with special reference to pathological effects

Parasitology ◽  
1967 ◽  
Vol 57 (2) ◽  
pp. 301-314 ◽  
Author(s):  
C. Arme ◽  
R. Wynne Owen
Keyword(s):  
Gasterosteus Aculeatus ◽  
Science Research ◽  
Liver Weight ◽  
Infected Fish ◽  
The Body ◽  
Schistocephalus Solidus ◽  
Maximum Value ◽  
Individual Host ◽  
Concurrent Infections ◽  
The Relationship

Infections are described of Gasterosteus aculeatus in a pond at Leeds with the plerocercoid larvae of Schistocephalus solidus.Very heavy infections were found in the summer of 1962 and early 1963; many fish harboured over 50 worms and the maximum was 130.For each individual host the relative percentage parasite-weight to host-weight has been determined (parasitization index). In more than 50% of the fish the P.I. exceeded 25; the maximum value was 68·5. The relationship between P.I., numbers of worms and weight of worms is described.Some effects of parasitization on the host are described; they include gross distension of the body, reduction of liver weight, reduction of packed cell volume of erythrocytes and delay in oocyte maturation. In some heavily parasitized individuals spawning is apparently inhibited.Concurrent infections with the microsporidian Glugea anomala are described.Our thanks are due to Mr A. Rennie, B.Sc., of the Yorkshire Ouse and Hull River Authority for drawing our attention to the source of infected sticklebacks, to Mr A. O. Holliday for the preparation of photographs and to Mr G. R. Standley for assistance in the preparation of the slide shown in PI. 1, fig. 3. We also wish to thank Dr J. N. Ball, Department of Zoology, University of Sheffield, for his helpful comments on the gonads of infected fish, and Professor J. M. Dodd, Department of Zoology, University of Leeds, for providing facilities and much helpful discussion. One of us (C. A.) gratefully acknowledges the receipt of a Science Research Council Research Studentship and Fellowship.

The optimal foraging strategy of its stickleback host constrains a parasite's complex life cycle

Behaviour ◽  
2005 ◽  
Vol 142 (7) ◽  
pp. 979-996 ◽  
Author(s):  
Manfred Milinski ◽  
Mira Christen
Keyword(s):  
Intermediate Host ◽  
Optimal Foraging ◽  
Gasterosteus Aculeatus ◽  
Foraging Strategy ◽  
Early Summer ◽  
Complex Life Cycle ◽  
Small Copepod ◽  
Size Classes ◽  
Optimal Foraging Strategy ◽  
Second Intermediate Host

AbstractThe cestode parasite Schistocephalus solidus' growth is limited by the size of its second intermediate host, the three-spined stickleback, Gasterosteus aculeatus. S. solidus should thus prefer a large stickleback as host. Since the stickleback is a predator of the parasite's previous intermediate host, a small copepod, the stickleback that consumes the infected copepod will probably be of a size for which this copepod has the optimal prey size. The optimal foraging decision of the stickleback may or may not be compatible with the parasite's preference. Infected copepods are present in early summer when both many size classes of young of the year and adult sticklebacks are potential predators. We offered laboratory bred three-spined sticklebacks of four size classes individually the choice among five prey types: two size classes of copepods, two classes of Daphnia of corresponding size as alternative prey and a third Daphnia size class that was larger than the larger copepod. We found that small copepods, the potential hosts of S. solidus, were most accepted by the smallest sticklebacks of about 1.5 cm of length, larger fish consumed a decreasing proportion; fish larger than 3.8 cm did not consume them at all. Experience with copepods over several weeks increased the acceptance for this prey to some extend but hardly in the largest fish. This suggests that S. solidus will end up usually in sticklebacks that are too small for the parasite so that it has to allow its host's further growth after infection to reach its definitive size.

Segregation and co-occurrence of larval cestodes in freshwater fishes in the Bothnian Bay, Finland

Parasitology ◽  
1992 ◽  
Vol 104 (1) ◽  
pp. 161-168 ◽  
Author(s):  
K. I. Andersen ◽  
E. T. Valtonen
Keyword(s):  
Fish Species ◽  
Definitive Host ◽  
Gasterosteus Aculeatus ◽  
Infected Fish ◽  
Fish Host ◽  
Cestode Species ◽  
Larval Population ◽  
Schistocephalus Solidus ◽  
Bothnian Bay ◽  
Diphyllobothrium Latum

SUMMARYTwo autogenic (Triaenophorus crassus and T. nodulosus) and four allogenic (Diphyllobothrium latum, D. dendriticum, D. ditremum and Schistocephalus solidus) larval cestode species were found in 13 out of 31 fish species studied from the Bothnian Bay, NE Baltic. Gasterosteus aculeatus was the most heavily infected fish with 4 larval cestode species; for two of them (D. ditremum and S. solidus) the three-spined stickleback was found to be the required fish intermediate host. Among allogenic cestode species, those restricted to different definitive host species segregated their larval population in relation to the fish host, while, for example, D. ditremum and S. solidus, both maturing in fish-eating birds, had the highest percentage of co-occurrences. D. dendriticum, which had the widest range of definitive hosts, was found in the greatest number (8) of fish species and co-occurred with all other species found except T. crassus. The two autogenic species totally segregated their larval population from each other although they both require pike as definitive host. The ecological and evolutionary relationships behind the patterns found for larval cestodes are discussed.

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