Incidence and intensity of Cyathocephalus truncatus and Schistocephalus solidus infection in Gasterosteus aculeatus

1982 ◽  
Vol 60 (5) ◽  
pp. 1091-1095 ◽  
Author(s):  
T. E. Reimchen

Cyathocephalus truncatus, a cestode usually found in salmonids, and plerocercoids of Schistocephalus solidus are reported from a population of Gasterosteus aculeatus on the Queen Charlotte Islands, British Columbia. Adult C. truncatus attached at the anterior of the intestine adjacent to the pyloric sphincter, whereas in salmonids the pyloric caeca is the usual attachment site. Mean intensities of infection for C. truncatus and S. solidus were 2.7 (maximum 26) and 3.4 (maximum 87), respectively, with intensities increasing in larger fish. The highest incidence of C. truncatus infection was from February to May (80%) and for S. solidus, from April to September (50%). Infection rates for C. truncatus during different seasons and among different length classes offish were directly correlated with the relative abundance of amphipods (the intermediate hosts of C. truncatus) in the fish stomachs. Possible modification of host feeding behaviour is indicated by a relative increase in the consumption of amphipods by infected fish.

2015 ◽  
Vol 61 (6) ◽  
pp. 991-995 ◽  
Author(s):  
Alexandre Budria ◽  
Ulrika Candolin

Abstract 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 whether an increased growth of filamentous algae affects the transmission of Diplostomum pseudospathaceum cercariae to the threespine stickleback Gasterosteus aculeatus, a common fish in eutrophied shallow waters. We exposed sticklebacks to trematode cercariae in the absence and presence of artificial filamentous algae, and recorded effects on the proportion of sticklebacks infected and the number of encysted metacercariae per fish. No significant effect of artificial algae on cercariae transmission was detected. However, the body size and the sex of the sticklebacks were strongly correlated with the number of encysted metacercariae per infected fish, with females and larger individuals being more infected. We discuss different factors that could have caused the difference in parasite transmission, including sex-related differences in body size and behaviour of sticklebacks.


Parasitology ◽  
2010 ◽  
Vol 137 (11) ◽  
pp. 1681-1686 ◽  
Author(s):  
D. C. HEINS ◽  
E. L. BIRDEN ◽  
J. A. BAKER

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.


Parasitology ◽  
2003 ◽  
Vol 126 (4) ◽  
pp. 369-378 ◽  
Author(s):  
M. CHRISTEN ◽  
M. MILINSKI

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.


Parasitology ◽  
1967 ◽  
Vol 57 (2) ◽  
pp. 301-314 ◽  
Author(s):  
C. Arme ◽  
R. Wynne Owen

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.


Behaviour ◽  
1995 ◽  
Vol 132 (15-16) ◽  
pp. 1223-1240 ◽  
Author(s):  
Iain Barber ◽  
Felicity A. Huntingford

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.


Parasitology ◽  
1992 ◽  
Vol 104 (1) ◽  
pp. 161-168 ◽  
Author(s):  
K. I. Andersen ◽  
E. T. Valtonen

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.


Parasitology ◽  
1971 ◽  
Vol 63 (3) ◽  
pp. 373-388 ◽  
Author(s):  
Linda Pennycuick

A population of three-spined sticklebacks, Gasterosteus aculealus, from a pond in Somerset was sampled about every three weeks for 19 months, a total of 1863 fish being collected. Three species of parasites were found in the fish: Schistocephalus solidus, Diplostomum gasterostei and Echinorhynchus clavula.Seasonal changes in the incidence and intensity of the three parasitic infections are described. In general the infections increased in summer and autumn and decreased in winter and spring, although in Schistocephalus the differences in the level of infection between the two years were greater than between seasons.The largest increases in the Schistocephalus and Echinorhynchus infections occurred in August and September and in the Diplostomum infection in May and June. These increases could be related to the feeding activity of the sticklebacks and to the abundance and level of infection of the Cyclops, Asellus and Limnaea pereger populations.Reduction in the sizes of the infections was by predation and death of heavily infected fish in the case of Schistocephalus and Diplostomum and mainly by death of individual worms in Echinorhynchus.These mechanisms are shown to be adapted to the life cycles of the parasites.I am most grateful to Dr H. D. Crofton for his help and encouragement during this investigation and to Dr R. A. Avery for useful discussions and advice. This work was supported by a Science Research Council research studentship and a NATO studentship.


Parasitology ◽  
2010 ◽  
Vol 137 (7) ◽  
pp. 1151-1158 ◽  
Author(s):  
D. C. HEINS ◽  
N. J. BROWN-PETERSON

SUMMARYThe objective of this study was to investigate the means by which Schistocephalus solidus might reduce annual fecundity in female threespine stickleback fish (Gasterosteus aculeatus) through processes of oocyte development. Histological examinations of specimens from one lake in Alaska in 2000 and 2001 were used to analyse the effects of S. solidus on recruitment of primary growth oocytes into vitellogenesis, atresia of vitellogenic oocytes, and the interspawning interval. The ratio of primary growth to late secondary growth (late vitellogenic) oocytes was significantly greater (P<0·01) among infected fish than uninfected ones in early-season samples from 2000 and 2001, revealing a decrease in recruitment of oocytes from primary growth into vitellogenic oocytes among infected females. The difference was marginally non-significant (P=0·087) in a mid-season sample from 2001 due to reductions in the entire pool of vitellogenic (early and late secondary growth) oocytes recruited prior to the spawning season in this determinate-fecundity species. Atresia among all vitellogenic oocytes was low and did not differ between infected and uninfected females. Histological estimations of the interspawning interval using post-ovulatory follicles showed no significant differences between infected and uninfected fish, suggesting that the number of spawnings in stickleback females each spawning season is unaffected by S. solidus infection. Thus, annual fecundity appears to be reduced only through recruitment of oocytes into vitellogenesis.


2019 ◽  
Author(s):  
Chloé Suzanne Berger ◽  
Nadia Aubin-Horth

ABSTRACTParasites with complex life cycles have been proposed to manipulate the behaviour of their intermediate hosts to increase the probability of reaching their final host. The cause of these drastic behavioural changes could be manipulation factors released by the parasite in its environment (the secretome), but this has rarely been assessed. We studied a non-cerebral parasite, the cestode Schistocephalus solidus, and its intermediate host, the threespine stickleback (Gasterosteus aculeatus), whose response to danger becomes significantly diminished when infected. These altered behaviours appear only during late infection, when the worm is ready to reproduce in its final avian host. Sympatric host-parasite pairs show higher infection success for parasites, suggesting that the secretome effects could differ for allopatric host-parasite pairs with independent evolutionary histories. We tested the effects of secretome exposure on behaviour by using secretions from the early and late infection of S. solidus and by injecting them in healthy sticklebacks from a sympatric and allopatric population. Contrary to our prediction, secretome from late infection worms did not result in more risky behaviours, but secretome from early infection resulted in more cautious hosts, only in fish from the allopatric population. Our results suggest that the secretome of Schistocephalus solidus contains molecules that can affect host behaviour, that the causes underlying the behavioural changes in infected sticklebacks are multifactorial, and that local adaptation between host-parasite pairs may extend to the response to the parasite’s secretome content.


Parasitology ◽  
2018 ◽  
Vol 146 (1) ◽  
pp. 97-104 ◽  
Author(s):  
David C. Heins ◽  
Kristine N. Moody ◽  
Sophia Miller

AbstractWe performed a long-term natural experiment investigating the impact of the diphyllobotriidean cestode Schistocephalus solidus on the body condition and clutch size (CS) of threespine stickleback Gasterosteus aculeatus, its second intermediate host, and the growth of larval parasites in host fish. We tested the hypothesis that single S. solidus infections were more virulent than multiple infections. We also asked whether the metrics of mean and total parasite mass (proxies for individual and total volume, respectively) were consistent with predictions of the resource constraints or the life history strategy (LHS) hypothesis for the growth of, hence exploitation by, larval helminths in intermediate hosts. The samples were drawn from Walby Lake, Alaska in eight of 11 years. Host body condition and CS (egg number per spawning bout) decreased significantly with intensity after adjustments for host size and parasite index. Thus, infections have an increasingly negative impact on measures of host fitness with greater intensity, in contrast to the hypothesis that single infections are more harmful than multiple infections. We also found that mean parasite mass decreased with intensity while total parasite mass increased with intensity as predicted by the LHS hypothesis.


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