scholarly journals The trophic vacuum and the evolution of complex life cycles in trophically transmitted helminths

2014 ◽  
Vol 281 (1793) ◽  
pp. 20141462 ◽  
Author(s):  
Daniel P. Benesh ◽  
James C. Chubb ◽  
Geoff A. Parker
Keyword(s):  
Niche Overlap ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Complex Life Cycles ◽  
High Fecundity ◽  
Modes Of Transmission ◽  
Host Penetration ◽  
Trophic Chains ◽  
Large Predators ◽  
Parasitic Worms

Parasitic worms (helminths) frequently have complex life cycles in which they are transmitted trophically between two or more successive hosts. Sexual reproduction often takes place in high trophic-level (TL) vertebrates, where parasites can grow to large sizes with high fecundity. Direct infection of high TL hosts, while advantageous, may be unachievable for parasites constrained to transmit trophically, because helminth propagules are unlikely to be ingested by large predators. Lack of niche overlap between propagule and definitive host (the trophic transmission vacuum) may explain the origin and/or maintenance of intermediate hosts, which overcome this transmission barrier. We show that nematodes infecting high TL definitive hosts tend to have more successive hosts in their life cycles. This relationship was modest, though, driven mainly by the minimum TL of hosts, suggesting that the shortest trophic chains leading to a host define the boundaries of the transmission vacuum. We also show that alternative modes of transmission, like host penetration, allow nematodes to reach high TLs without intermediate hosts. We suggest that widespread omnivory as well as parasite adaptations to increase transmission probably reduce, but do not eliminate, the barriers to the transmission of helminths through the food web.

Influence of the transmission of parasites from prey fishes on the composition of the parasite community of a predatory fish

1995 ◽  
Vol 52 (S1) ◽  
pp. 233-245 ◽  
Author(s):  
E. Tellervo Valtonen ◽  
Markku Julkunen
Keyword(s):  
Parasite Community ◽  
Life Cycles ◽  
Predatory Fish ◽  
Helminth Parasites ◽  
Intermediate Hosts ◽  
Complex Life Cycles ◽  
Lota Lota ◽  
Gymnocephalus Cernuus ◽  
Adult Trematode ◽  
Bothnian Bay

Helminth parasites and diet of seven freshwater fishes (Lota lota and six common prey species) from the Bothnian Bay, Baltic Sea, were studied monthly or bimonthly during 1978. Twenty-one of the 32 parasites with complex life cycles were shared between Lota lota and its prey fishes and are thus transmissible from prey to predator. Gymnocephalus cernuus and L. lota had the greatest number of shared species (13). Larval and adult cestodes, nematodes, and acanthocephalans could re-establish in the predator, but only one adult trematode was capable of this transition. Infracommunity species diversity was highest in L. lota (eH′ = 3.54), which also had the most species (24), the highest mean number of species and individuals of a given species per fish (6.3 and 62, respectively), and the greatest number of worms in one fish (520). Variety of diet was key in determining exposure to parasite species. However, most specificity finally determined if a given parasite could establish and mature. No ecologically explicable suites of parasites were found in any fish species, except in a few cases where parasites used related intermediate hosts. However, the composition of these suites was not retained in the predator. Unlike in L. lota, important parasites of prey fishes were typically specialists.

Pan-American marine coastal distribution of the acanthocephalan Profilicollis altmani based on morphometric and phylogenetic analyses of cystacanths from the mole crab Emerita brasiliensis

2016 ◽  
Vol 91 (3) ◽  
pp. 371-375 ◽  
Author(s):  
S.M. Rodríguez ◽  
G. D'Elía
Keyword(s):  
Phylogenetic Analyses ◽  
Atlantic Coast ◽  
Life Cycles ◽  
Morphological Evidence ◽  
South American ◽  
Intermediate Hosts ◽  
Complex Life Cycles ◽  
Present Complex ◽  
The World ◽  
Pan American

AbstractThorny-headed acanthocephalan worms of the genus Profilicollis are widely distributed in the oceans of the world and present complex life cycles with intermediate and definitive hosts. The genus is still poorly known, with an unstable taxonomy and, for most species, incompletely characterized geographical distributions. In this study, based on molecular and morphological evidence, we report that the species Profilicollis altmani is also distributed along the South American Atlantic coast, using the mole crab Emerita brasiliensis as an intermediate host. As such, our record shows that P. altmani has a Pan-American distribution where five species of Emerita are utilized as intermediate hosts.

scholarly journals Comparative analysis of helminth infectivity: growth in intermediate hosts increases establishment rates in the next host

2021 ◽  
Vol 288 (1947) ◽  
Author(s):  
Spencer Froelick ◽  
Laura Gramolini ◽  
Daniel P. Benesh
Keyword(s):  
Life Cycle ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Life Stages ◽  
Intermediate Hosts ◽  
Cycle Progression ◽  
Recovery Rates ◽  
High Doses ◽  
Parasitic Worms ◽  
Higher Doses

Parasitic worms (i.e. helminths) commonly infect multiple hosts in succession before reproducing. At each life cycle step, worms may fail to infect the next host, and this risk accumulates as life cycles include more successive hosts. Risk accumulation can be minimized by having high establishment success in the next host, but comparisons of establishment probabilities across parasite life stages are lacking. We compiled recovery rates (i.e. the proportion of parasites recovered from an administered dose) from experimental infections with acanthocephalans, cestodes and nematodes. Our data covered 127 helminth species and 16 913 exposed hosts. Recovery rates increased with life cycle progression (11%, 29% and 46% in first, second and third hosts, respectively), because larger worm larvae had higher recovery, both within and across life stages. Recovery declined in bigger hosts but less than it increased with worm size. Higher doses were used in systems with lower recovery, suggesting that high doses are chosen when few worms are expected to establish infection. Our results indicate that growing in the small and short-lived hosts at the start of a complex life cycle, though dangerous, may substantially improve parasites' chances of completing their life cycles.

scholarly journals Parasite-modified behaviour in non-trophic transmission: trematode parasitism increases the attraction between snail intermediate hosts

2020 ◽  
Vol 98 (7) ◽  
pp. 417-424
Author(s):  
L.K. Eliuk ◽  
S. Brown ◽  
R.C. Wyeth ◽  
J.T. Detwiler
Keyword(s):  
Life Cycles ◽  
Intermediate Hosts ◽  
Free Swimming ◽  
Complex Life Cycles ◽  
Trophic Transmission ◽  
Y Maze ◽  
Second Intermediate Host ◽  
Behavioural Experiments ◽  
Lymnaea Elodes ◽  
Host Parasite

Many parasites with complex life cycles cause host behavioural changes that increase the likelihood of transmission to the next host. Parasite modification is often found in trophic transmission, but its influence on non-trophic transmission is unclear. In trematodes, transmission from the first to second intermediate host is non-trophic, suggesting that free-swimming larvae (cercariae) emerging in closer proximity to the next host would have higher transmission success. We performed a series of behavioural experiments with echinostome trematodes and their snail hosts to determine if potential second hosts (ramshorn snail, genus Planorbella Haldeman, 1842) were more attracted to parasitized first hosts (marsh pondsnail, Lymnaea elodes Say, 1821). In a Y maze, a responding snail (Planorbella sp.) was placed in the base and its response to five treatments was assessed: no stimulus, turion duckweed (Lemna turionifera Landolt; a food item), non-parasitized L. elodes, parasitized L. elodes, and finally parasitized versus non-parasitized L. elodes. Snails showed some attraction to uninfected snails, but had a stronger response to infected first host snails. These results indicate that potential second host snails were more attracted to parasitized, heterospecific first host snails over non-parasitized heterospecific snails. This study demonstrates that echinostome trematodes alter snail behaviour by changing navigational choices in uninfected potential hosts through a chemical communication mechanism.

scholarly journals When should a trophically and vertically transmitted parasite manipulate its intermediate host? The case of Toxoplasma gondii

2013 ◽  
Vol 280 (1765) ◽  
pp. 20131143 ◽  
Author(s):  
Maud Lélu ◽  
Michel Langlais ◽  
Marie-Lazarine Poulle ◽  
Emmanuelle Gilot-Fromont ◽  
Sylvain Gandon
Keyword(s):  
Toxoplasma Gondii ◽  
Vertical Transmission ◽  
Death Rate ◽  
Predation Rate ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Complex Life Cycles ◽  
Virulent Strains ◽  
Host Behaviour ◽  
Different Levels

Parasites with complex life cycles are expected to manipulate the behaviour of their intermediate hosts (IHs), which increase their predation rate and facilitate the transmission to definitive hosts (DHs). This ability, however, is a double-edged sword when the parasite can also be transmitted vertically in the IH. In this situation, as the manipulation of the IH behaviour increases the IH death rate, it conflicts with vertical transmission, which requires healthy and reproducing IHs. The protozoan Toxoplasma gondii , a widespread pathogen, combines both trophic and vertical transmission strategies. Is parasite manipulation of host behaviour still adaptive in this situation? We model the evolution of the IH manipulation by T. gondii to study the conflict between these two routes of transmission under different epidemiological situations. Model outputs show that manipulation is particularly advantageous for virulent strains and in epidemic situations, and that different levels of manipulation may evolve depending on the sex of the IH and the transmission routes considered. These results may help to understand the variability of strain characteristics encountered for T. gondii and may extend to other trophically transmitted parasites.

Tranmission pattern differences of miracidia and cercariae larval stages of digenetic trematode parasites

2016 ◽  
Vol 61 (4) ◽  
Author(s):  
Michael R. Zimmermann ◽  
Kyle E. Luth ◽  
Gerald W. Esch
Keyword(s):  
Abiotic Factors ◽  
Field Studies ◽  
Life Cycles ◽  
Digenetic Trematode ◽  
Snail Species ◽  
Intermediate Hosts ◽  
Complex Life Cycles ◽  
Larval Stages ◽  
Digenetic Trematodes ◽  
Trematode Parasites

AbstractDigenetic trematodes have complex life cycles involving multiple hosts and free-living larval stages. Some species have 2 lar-val stages that infect snails, with miracidia and cercariae using these molluscs as first and second intermediate hosts, respec-tively. Although both larval stages may infect the same snail species, this is accomplished using different chemical cues and may be influenced by different biotic and abiotic factors. Significant differences in the infection patterns of these parasitic stages regarding host size and density were observed in 2 separate field studies. The prevalence of sporocysts/rediae and mean abundance of

The phylogeny and life cycle of two species ofProfilicollis(Acanthocephala: Polymorphidae) in marine hosts off the Pacific coast of Chile

2016 ◽  
Vol 91 (5) ◽  
pp. 589-596 ◽  
Author(s):  
S.M. Rodríguez ◽  
G. D'Elía ◽  
N. Valdivia
Keyword(s):  
Life Cycle ◽  
Pacific Coast ◽  
Interaction Network ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Complex Life Cycles ◽  
Marine Habitats ◽  
East Pacific ◽  
The Pacific ◽  
Shed Light

AbstractResolving complex life cycles of parasites is a major goal of parasitological research. The aim of this study was to analyse the life cycle of two species of the genusProfilicollis,the taxonomy of which is still unstable and life cycles unclear. We extracted individuals ofProfilicollisfrom two species of crustaceans (intermediate hosts) and four species of seagulls (definitive hosts) from sandy-shore and estuarine habitats along the south-east Pacific coast of Chile. Mitochondrial DNA analyses showed that two species ofProfilicollisinfected intermediate hosts from segregated habitats: whileP. altmanilarvae infected exclusively molecrabs of the genusEmeritafrom fully marine habitats,P. antarcticuslarvae infected the crabHemigrapsus crenulatusfrom estuarine habitats. Moreover,P. altmanicompleted its life cycle in four seagulls,Chroicocephalus maculipennis, Leucopheus pipixcan, Larus modestusandL. dominicanus,whileP. antarcticus, on the other hand, completed its life cycle in the kelp gullL. dominicanus. Accordingly, our results show that two congeneric parasites use different and spatially segregated species as intermediate hosts, and both are capable of infecting one species of definitive hosts. As such, our analyses allow us to shed light on a complex interaction network.

scholarly journals Does a complex life cycle affect adaptation to environmental change? Genome-informed insights for characterizing selection across complex life cycle

2021 ◽  
Vol 288 (1964) ◽  
Author(s):  
Molly A. Albecker ◽  
Laetitia G. E. Wilkins ◽  
Stacy A. Krueger-Hadfield ◽  
Samuel M. Bashevkin ◽  
Matthew W. Hahn ◽  
...  
Keyword(s):  
Life Cycle ◽  
Empirical Studies ◽  
Life Cycles ◽  
Complex Life Cycle ◽  
Ecological Niches ◽  
Life Stages ◽  
Complex Life Cycles ◽  
High Fecundity ◽  
Trade Offs ◽  
Frequency Changes

Complex life cycles, in which discrete life stages of the same organism differ in form or function and often occupy different ecological niches, are common in nature. Because stages share the same genome, selective effects on one stage may have cascading consequences through the entire life cycle. Theoretical and empirical studies have not yet generated clear predictions about how life cycle complexity will influence patterns of adaptation in response to rapidly changing environments or tested theoretical predictions for fitness trade-offs (or lack thereof) across life stages. We discuss complex life cycle evolution and outline three hypotheses—ontogenetic decoupling, antagonistic ontogenetic pleiotropy and synergistic ontogenetic pleiotropy—for how selection may operate on organisms with complex life cycles. We suggest a within-generation experimental design that promises significant insight into composite selection across life cycle stages. As part of this design, we conducted simulations to determine the power needed to detect selection across a life cycle using a population genetic framework. This analysis demonstrated that recently published studies reporting within-generation selection were underpowered to detect small allele frequency changes (approx. 0.1). The power analysis indicates challenging but attainable sampling requirements for many systems, though plants and marine invertebrates with high fecundity are excellent systems for exploring how organisms with complex life cycles may adapt to climate change.

Behavioural and physiological effects of the trophically transmitted cestode parasite, Cyathocephalus truncatus, on its intermediate host, Gammarus pulex

Parasitology ◽  
2007 ◽  
Vol 134 (12) ◽  
pp. 1839-1847 ◽  
Author(s):  
N. FRANCESCHI ◽  
T. RIGAUD ◽  
Y. MORET ◽  
F. HERVANT ◽  
L. BOLLACHE
Keyword(s):  
Behavioural Change ◽  
Predation Rate ◽  
Life Cycles ◽  
Gammarus Pulex ◽  
Intermediate Hosts ◽  
Host Reaction ◽  
Complex Life Cycles ◽  
Cestode Parasite ◽  
Behavioural Manipulation ◽  
Pathogenic Effects

SUMMARYSome parasites with complex life-cycles are able to manipulate the behaviour of their intermediate hosts in a way that increases their transmission to the next host. Gammarids infected by the tapeworm Cyathocephalus truncatus (Cestoda: Spathebothriidea) are known to be more predated by fish than uninfected ones, but potential behavioural manipulation by the parasite has never been investigated. In this study, we tested the hypothesis that C. truncatus is able to manipulate the behaviour of one of its intermediate hosts, Gammarus pulex (Crustacea: Amphipoda). To assess if any behavioural change was linked to other phenotypic alterations, we also measured the immunity of infected and uninfected individuals and investigated the pathogenic effects of the parasite. Infected gammarids were significantly less photophobic than uninfected ones, but no effect of infection on the level of immune defence was found. The results on survival, swimming activity and oxygen consumption suggest that the parasite also has various pathogenic effects. However, the alteration in host phototaxis was not correlated to some of these pathogenic effects. Therefore, we propose that the modification in host reaction to light is a behavioural manipulation, explaining the previously observed increase of gammarid predation rate.

Pairing success and sperm reserve of male Gammarus pulex infected by Cyathocephalus truncatus (Cestoda: Spathebothriidea)

Parasitology ◽  
2011 ◽  
Vol 138 (11) ◽  
pp. 1429-1435 ◽  
Author(s):  
MATTHIAS GALIPAUD ◽  
ZOÉ GAUTHEY ◽  
LOÏC BOLLACHE
Keyword(s):  
Mate Guarding ◽  
Potential Effect ◽  
Life Cycles ◽  
Mating Strategies ◽  
Gammarus Pulex ◽  
Physiological Changes ◽  
Sperm Number ◽  
Intermediate Hosts ◽  
Complex Life Cycles ◽  
Rival Male

SUMMARYManipulative parasites with complex life cycles are known to induce behavioural and physiological changes in their intermediate hosts. Cyathocephalus truncatus is a manipulative parasite which infects Gammarus pulex as intermediate host. G. pulex males display pre-copulatory mate guarding as a response to male-male competition for access to receptive females. In this paper, we tested the influence that C. truncatus-infection might have on male G. pulex sperm number and pairing success. We considered 3 classes of G. pulex males in our experiments: (i) uninfected males found paired in the field, (ii) uninfected males found unpaired in the field, or (iii) infected males found unpaired in the field. Both infected males and uninfected unpaired males paired less with a new female than uninfected paired males did. Furthermore, infected males appear to be at a strong disadvantage when directly competing for females with a healthy rival male, and had fewer sperm in their testes. We discuss the potential effect of male and female mating strategies on such male host mating alteration.

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