scholarly journals Inter- and intraspecific conflicts between parasites over host manipulation

2016 ◽  
Vol 283 (1824) ◽  
pp. 20152870 ◽  
Author(s):  
Nina Hafer ◽  
Manfred Milinski
Keyword(s):  
Intermediate Host ◽  
Fish Host ◽  
Host Manipulation ◽  
Schistocephalus Solidus ◽  
Common Strategy ◽  
First Intermediate Host

Host manipulation is a common strategy by which parasites alter the behaviour of their host to enhance their own fitness. In nature, hosts are usually infected by multiple parasites. This can result in a conflict over host manipulation. Studies of such a conflict in experimentally infected hosts are rare. The cestode Schistocephalus solidus (S) and the nematode Camallanus lacustris (C) use copepods as their first intermediate host. They need to grow for some time inside this host before they are infective and ready to be trophically transmitted to their subsequent fish host. Accordingly, not yet infective parasites manipulate to suppress predation. Infective ones manipulate to enhance predation. We experimentally infected laboratory-bred copepods in a manner that resulted in copepods harbouring (i) an infective C plus a not yet infective C or S, or (ii) an infective S plus a not yet infective C. An infective C completely sabotaged host manipulation by any not yet infective parasite. An infective S partially reduced host manipulation by a not yet infective C. We hence show experimentally that a parasite can reduce or even sabotage host manipulation exerted by a parasite from a different species.

The infectivity, growth, and virulence of the cestode Schistocephalus solidus in its first intermediate host, the copepod Macrocyclops albidus

Parasitology ◽  
1997 ◽  
Vol 115 (3) ◽  
pp. 317-324 ◽  
Author(s):  
C. WEDEKIND
Keyword(s):  
Intermediate Host ◽  
Adult Stage ◽  
Dilution Effect ◽  
Multiple Infections ◽  
Schistocephalus Solidus ◽  
Host Mortality ◽  
Copepodid Stage ◽  
First Intermediate Host ◽  
Observation Period ◽  
Growth And Reproduction

In an experiment to study the infectivity, growth and virulence of Schistocephalus solidus in their first intermediate host, copepods of the species Macrocyclops albidus were kept singly and exposed to up to 9 coracidia. Eleven or 14 days post-infection (p.i.) the presence and growth of the cestode larvae relative to survival, growth and reproduction of their host was determined. As expected, the probability of a copepod becoming infected increased with increasing numbers of parasites administered. However, the chances of a single coracidium establishing in a copepod also increased with increasing numbers of coracidia administered, which indicates that the parasites profit from a dilution effect of the host's defence. Copepod size or developmental stage had no significant effect on the infection, but 14 days p.i., constraining effects of copepod size on the growth of the parasites were apparent. Moreover, procercoids in multiple infections grew smaller and developed their cercomer at a smaller size than those in single infections. No significant effect of the parasite on host mortality was found within the observation period. However, growth between the 5th copepodid stage and adult stage was negatively affected by infection. An infection with S. solidus was also strongly linked with host reproduction: infected females were more likely to bear an egg sac at the end of the experiment than non-infected ones. These egg sacs, however, contained fewer eggs.

scholarly journals The parasite Schistocephalus solidus secretes proteins with putative host manipulation functions

2020 ◽  
Author(s):  
Chloé Suzanne Berger ◽  
Jérôme Laroche ◽  
Halim Maaroufi ◽  
Hélène Martin ◽  
Kyung-Mee Moon ◽  
...  
Keyword(s):  
Gasterosteus Aculeatus ◽  
Gene Prediction ◽  
Life Stage ◽  
Complex Mixture ◽  
Fish Host ◽  
Complex Life Cycle ◽  
Host Manipulation ◽  
Immune Functions ◽  
Phospholipid Scramblase ◽  
Schistocephalus Solidus

ABSTRACTManipulative parasites are predicted to liberate molecules in their external environment acting as manipulation factors with biological functions implicated in their host’s physiological and behavioural alterations. These manipulation factors are expected to be part of a complex mixture called the secretome. While the secretomes of various parasites have been described, there is very little data for a putative manipulative parasite. Here, we used proteomics to characterize the secretome of a model cestode with a complex life cycle based on trophic transmission. We studied Schistocephalus solidus during the life stage in which behavioural changes have been described in its obligatory intermediate fish host, the threespine stickleback (Gasterosteus aculeatus). We re-sequenced the genome of S. solidus using a combination of long and short reads to improve protein coding gene prediction and annotation for this parasite species. We then described the whole worm’s proteome and its secretome during fish host infection, using LC-MS/MS. A total of 2 290 proteins were detected in the proteome of S. solidus, with 30 proteins detected only in the secretome. We found that the secretome contained proteases, proteins with neural and immune functions, as well as proteins involved in cell communication. We also detected Receptor-type tyrosine-protein phosphatases, which were reported in other parasitic systems to be strong manipulation factors. The secretome also contained a Phospholipid scramblase that clustered phylogenetically with a stickleback Phospholipid scramblase, suggesting it could have the potential to interfere with the function of the scramblase in the host’s brain. Finally, we detected 12 S. solidus-specific proteins in the secretome that may play important roles in host-parasite interactions. Our results suggest that this parasite liberates molecules with putative host manipulation functions in the host and that many of them are species specific.

scholarly journals Experimental evolution of parasitic host manipulation

2019 ◽  
Vol 286 (1895) ◽  
pp. 20182413 ◽  
Author(s):  
Nina Hafer-Hahmann
Keyword(s):  
Experimental Evolution ◽  
Fish Host ◽  
Host Manipulation ◽  
Extended Phenotype ◽  
Parasite Fitness ◽  
Three Generations ◽  
Schistocephalus Solidus ◽  
Trade Offs

Host manipulation is a parasite-induced alteration of a host's phenotype that increases parasite fitness. However, if genetically encoded in the parasite, it should be under selection in the parasite. Such host manipulation has often been assumed to be energetically costly, which should restrict its evolution. Evidence of such costs, however, remains elusive. The trophically transmitted cestode Schistocephalus solidus manipulates the activity of its first intermediate copepod host to reduce its predation susceptibility before the parasite is ready for transmission. Thereafter, S. solidus increases host activity to facilitate transmission to its subsequent fish host. I selected S. solidus for or against host manipulation over three generations to investigate the evolvability of manipulation and identify potential trade-offs. Host manipulation responded to selection, confirming that this trait is heritable in the parasite and hence can present an extended phenotype. Changes in host manipulation were not restrained by any obvious costs.

scholarly journals Does resource availability affect host manipulation? – an experimental test with Schistocephalus solidus

2015 ◽  
Vol 1 ◽  
Author(s):  
NINA HAFER ◽  
DANIEL P. BENESH
Keyword(s):  
Resource Availability ◽  
Parasite Transmission ◽  
Host Manipulation ◽  
Food Treatment ◽  
Schistocephalus Solidus ◽  
Trade Offs ◽  
Common Strategy ◽  
Food Conditions ◽  
The Difference ◽  
Host Behaviour

SUMMARYHost manipulation is a common strategy of parasites employed to increase their fitness by changing the phenotype of their hosts. Whether host manipulation might be affected by environmental factors such as resource availability, has received little attention. We experimentally infected laboratory-bred copepods with the cestodeSchistocephalus solidus, submitted infected and uninfected copepods to either a high or a low food treatment, and measured their behaviour. Infection reduced host activity and speed in both feeding treatments. However, the difference between the infected and uninfected copepods was smaller under low food conditions, because uninfected, but not infected, copepods moved slower under these conditions. We suggest that these differences are mediated by the physical condition of copepods rather than changes in how strongly the parasite manipulated host behaviour. Additionally, we measured three fitness-relevant traits (growth, development and infection rate in the next host) of the parasite to identify potential trade-offs with host manipulation. The largest parasites in copepods appeared the least manipulative, i.e. their hosts showed the smallest behavioural alterations, but this may again reflect variation in copepod condition, rather than life history trade-offs between parasite growth and host manipulation. Our results point to the possibility that parasite transmission depends on environmental conditions.

scholarly journals Tapeworm manipulation of copepod behaviour: parasite genotype has a larger effect than host genotype

2019 ◽  
Vol 15 (9) ◽  
pp. 20190495 ◽  
Author(s):  
Daniel P. Benesh
Keyword(s):  
Host Responses ◽  
Host Manipulation ◽  
Parasite Genotype ◽  
Host Genotype ◽  
Genotype I ◽  
Schistocephalus Solidus ◽  
Host Behaviour ◽  
Full Factorial ◽  
Host Genes ◽  
First Intermediate Host

Compared with uninfected individuals, infected animals can exhibit altered phenotypes. The changes often appear beneficial to parasites, leading to the notion that modified host phenotypes are extended parasite phenotypes, shaped by parasite genes. However, the phenotype of a parasitized individual may reflect parasitic manipulation, host responses to infection or both, and disentangling the contribution of parasite genes versus host genes to these altered phenotypes is challenging. Using a tapeworm ( Schistocephalus solidus ) infecting its copepod first intermediate host, I performed a full-factorial, cross-infection experiment with five host and five parasite genotypes. I found that a behavioural trait modified by infection, copepod activity, was affected by both host and parasite genotype. There was no clear evidence for host genotype by parasite genotype interactions. Several observations indicated that host behaviour was chiefly determined by parasite genes: (i) all infected copepods, regardless of host or parasite genotype, exhibited behavioural changes, (ii) parasitism reduced the differences among copepod genotypes, and (iii) within infected copepods, parasite genotype had twice as large an effect on behaviour as host genotype. I conclude that the altered behaviour of infected copepods primarily represents an extended parasite phenotype, and I discuss how genetic variation in parasitic host manipulation could be maintained.

scholarly journals The parasite Schistocephalus solidus secretes proteins with putative host manipulation functions

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Chloé Suzanne Berger ◽  
Jérôme Laroche ◽  
Halim Maaroufi ◽  
Hélène Martin ◽  
Kyung-Mee Moon ◽  
...  
Keyword(s):  
Gasterosteus Aculeatus ◽  
Gene Prediction ◽  
Life Stage ◽  
Cell Communication ◽  
Complex Mixture ◽  
Fish Host ◽  
Complex Life Cycle ◽  
Host Manipulation ◽  
Immune Functions ◽  
Schistocephalus Solidus

Abstract Background Manipulative parasites are thought to liberate molecules in their external environment, acting as manipulation factors with biological functions implicated in their host’s physiological and behavioural alterations. These manipulation factors are part of a complex mixture called the secretome. While the secretomes of various parasites have been described, there is very little data for a putative manipulative parasite. It is necessary to study the molecular interaction between a manipulative parasite and its host to better understand how such alterations evolve. Methods Here, we used proteomics to characterize the secretome of a model cestode with a complex life cycle based on trophic transmission. We studied Schistocephalus solidus during the life stage in which behavioural changes take place in its obligatory intermediate fish host, the threespine stickleback (Gasterosteus aculeatus). We produced a novel genome sequence and assembly of S. solidus to improve protein coding gene prediction and annotation for this parasite. We then described the whole worm’s proteome and its secretome during fish host infection using LC–MS/MS. Results A total of 2290 proteins were detected in the proteome of S. solidus, and 30 additional proteins were detected specifically in the secretome. We found that the secretome contains proteases, proteins with neural and immune functions, as well as proteins involved in cell communication. We detected receptor-type tyrosine-protein phosphatases, which were reported in other parasitic systems to be manipulation factors. We also detected 12 S. solidus-specific proteins in the secretome that may play important roles in host–parasite interactions. Conclusions Our results suggest that S. solidus liberates molecules with putative host manipulation functions in the host and that many of them are species-specific. Graphical abstract

Reproduction and caste ratios under stress in trematode colonies with a division of labour

Parasitology ◽  
2013 ◽  
Vol 140 (7) ◽  
pp. 825-832 ◽  
Author(s):  
MELANIE M. LLOYD ◽  
ROBERT POULIN
Keyword(s):  
Intermediate Host ◽  
Reproductive Output ◽  
Environmental Variability ◽  
Division Of Labour ◽  
Environmental Pressures ◽  
Caste Ratio ◽  
Infection Types ◽  
First Intermediate Host

SUMMARYTrematodes form clonal colonies in their first intermediate host. Individuals are, depending on species, rediae or sporocysts (which asexually reproduce) and cercariae (which develop within rediae or sporocysts and infect the next host). Some species use a division of labour within colonies, with 2 distinct redial morphs: small rediae (non-reproducing) and large rediae (individuals which produce cercariae). The theory of optimal caste ratio predicts that the ratio of caste members (small to large rediae) responds to environmental variability. This was tested in Philophthalmus sp. colonies exposed to host starvation and competition with the trematode, Maritrema novaezealandensis. Philophthalmus sp. infected snails, with and without M. novaezealandensis, were subjected to food treatments. Reproductive output, number of rediae, and the ratio of small to large rediae were compared among treatments. Philophthalmus sp. colonies responded to host starvation and competition; reproductive output was higher in well-fed snails of both infection types compared with snails in lower food treatments and well-fed, single infected snails compared with well-fed double infected snails. Furthermore, the caste ratio in Philophthalmus sp. colonies was altered in response to competition. This is the first study showing caste ratio responses to environmental pressures in trematodes with a division of labour.

scholarly journals The Effect of Trematode Parasites on the Growth of Littorina Neritoides (L.)

1941 ◽  
Vol 25 (1) ◽  
pp. 69-80 ◽  
Author(s):  
Miriam Rothschild
Keyword(s):  
Intermediate Host ◽  
Large Size ◽  
Size Groups ◽  
Second Intermediate Host ◽  
Upward Slope ◽  
Accelerated Growth ◽  
The Difference ◽  
First Intermediate Host ◽  
Low Rate ◽  
Trematode Parasites

If the number of infections with (a) trematode parthenitae and cercariae using Littorina neritoides as first intermediate host only, and (b) encysted metacercariae using L. neritoides as second intermediate host only, are plotted against the size of the snails, two different curves result. The first shows a low rate of infection in the small size groups, but a steep upward slope rising to 91% in the large size groups. The second shows a curve increasing uniformly to 87% infection.Possible interpretations are discussed, and it is concluded that the difference is probably due to the fact that primary infections cause accelerated growth in the host.

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