Crowding in the first intermediate host does not affect infection probability in the second host in two helminths

2018 ◽  
Vol 93 (2) ◽  
pp. 172-176
Author(s):  
D.P. Benesh
Keyword(s):  
Infection Intensity ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Larval Size ◽  
Establishment Probability ◽  
Constant Dose ◽  
Disproportionate Number ◽  
Dependent Growth ◽  
Average Size ◽  
Larval Crowding

AbstractWhen many worms co-infect the same host, their average size is often reduced. This negative density-dependent growth is called the crowding effect. Crowding has been reported many times for worms in their intermediate hosts, but rarely have the fitness consequences of crowding been examined. This study tested whether larval crowding reduces establishment success in the next host for two parasites with complex life cycles, the nematode Camallanus lacustris and the cestode Schistocephalus solidus. Infected copepods, the first host, were fed to sticklebacks, the second host. Fish received a constant dose, but the infection intensity in copepods was varied (e.g. giving two singly infected copepods or one doubly infected copepod). Worms from higher-intensity infections did not have significantly reduced infection success in fish. However, crowded treatments had a disproportionate number of low and high infection rates, and although this trend was not significant, it hints at the possibility that multiple worms within a copepod are more likely to either all infect or all die when transmitted to the next host. These results indicate that a smaller larval size due to crowding need not reduce the establishment probability of a worm in the next host.

scholarly journals Causes of intraspecific variation in body size among trematode metacercariae

2009 ◽  
Vol 83 (3) ◽  
pp. 289-293 ◽  
Author(s):  
I. Saldanha ◽  
T.L.F. Leung ◽  
R. Poulin
Keyword(s):  
Body Size ◽  
Body Length ◽  
Large Fraction ◽  
Infection Intensity ◽  
Intermediate Hosts ◽  
Intensity Of Infection ◽  
Mean Diameter ◽  
The Mean ◽  
Disproportionate Number ◽  
Dependent Growth

AbstractInequalities in body size among adult helminths can result in inequalities in reproductive output, with consequences for population dynamics and genetics. These inequalities can result from growth differences among larval worms inside intermediate hosts that persist into the adult stage. Here, we investigate the effects of both host body size and intensity of infection on the sizes of metacercariae of the trematode Maritrema novaezealandensis (Microphallidae) inside their second intermediate host, the isopod Paridotea ungulata (Idoteidae). Among the more than 1500 metacercariae recovered and individually measured, there was no relationship between the mean diameter of metacercarial cysts per isopod and isopod body length. However, intensity of infection correlated negatively with the mean diameter of cysts within an isopod, i.e. metacercariae in crowded infections attained smaller sizes on average. In contrast, the variability in cyst sizes per isopod, measured as the coefficient of variation, was independent of both isopod body length and infection intensity. Our results show that a disproportionate number of relatively small metacercariae come from the relatively few hosts in which a large fraction of all metacercariae are aggregated. The combination of aggregation and intensity-dependent growth generates inequalities in sizes among metacercariae that will be passed on to adult worm populations in definitive hosts.

scholarly journals Leeches as the intermediate host for strigeid trematodes: genetic diversity and taxonomy of the genera Australapatemon Sudarikov, 1959 and Cotylurus Szidat, 1928

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Ewa Pyrka ◽  
Gerard Kanarek ◽  
Grzegorz Zaleśny ◽  
Joanna Hildebrand
Keyword(s):  
Intermediate Host ◽  
Life Cycles ◽  
Coi Gene ◽  
Small Rivers ◽  
Ecological Niches ◽  
Its2 Region ◽  
28S Rrna ◽  
Intermediate Hosts ◽  
Internal Transcribed Spacer Region ◽  
Wide Range

Abstract Background Leeches (Hirudinida) play a significant role as intermediate hosts in the circulation of trematodes in the aquatic environment. However, species richness and the molecular diversity and phylogeny of larval stages of strigeid trematodes (tetracotyle) occurring in this group of aquatic invertebrates remain poorly understood. Here, we report our use of recently obtained sequences of several molecular markers to analyse some aspects of the ecology, taxonomy and phylogeny of the genera Australapatemon and Cotylurus, which utilise leeches as intermediate hosts. Methods From April 2017 to September 2018, 153 leeches were collected from several sampling stations in small rivers with slow-flowing waters and related drainage canals located in three regions of Poland. The distinctive forms of tetracotyle metacercariae collected from leeches supplemented with adult Strigeidae specimens sampled from a wide range of water birds were analysed using the 28S rDNA partial gene, the second internal transcribed spacer region (ITS2) region and the cytochrome c oxidase (COI) fragment. Results Among investigated leeches, metacercariae of the tetracotyle type were detected in the parenchyma and musculature of 62 specimens (prevalence 40.5%) with a mean intensity reaching 19.9 individuals. The taxonomic generic affiliation of metacercariae derived from the leeches revealed the occurrence of two strigeid genera: Australapatemon Sudarikov, 1959 and Cotylurus Szidat, 1928. Phylogenetic reconstructions based on the partial 28S rRNA gene, ITS2 region and partial COI gene confirmed the separation of the Australapatemon and Cotylurus clades. Taking currently available molecular data and our results into consideration, recently sequenced tetracotyle of Australapatemon represents most probably Au. minor; however, unclear phylogenetic relationships between Au. burti and Au. minor reduce the reliability of this conclusion. On the other hand, on the basis of the obtained sequences, supplemented with previously published data, the metacercariae of Cotylurus detected in leeches were identified as two species: C. strigeoides Dubois, 1958 and C. syrius Dubois, 1934. This is the first record of C. syrius from the intermediate host. Conclusions The results of this study suggest the separation of ecological niches and life cycles between C. cornutus (Rudolphi, 1808) and C. strigeoides/C. syrius, with potential serious evolutionary consequences for a wide range of host–parasite relationships. Moreover, phylogenetic analyses corroborated the polyphyletic character of C. syrius, the unclear status of C. cornutus and the separate position of Cotylurus raabei Bezubik, 1958 within Cotylurus. The data demonstrate the inconsistent taxonomic status of the sequenced tetracotyle of Australapatemon, resulting, in our opinion, from the limited availability of fully reliable, comparative sequences of related taxa in GenBank.

scholarly journals Time-dependent growth of crystalline Au0-nanoparticles in cyanobacteria as self-reproducing bioreactors: 2.Anabaena cylindrica

2016 ◽  
Vol 7 ◽  
pp. 312-327 ◽  
Author(s):  
Liz M Rösken ◽  
Felix Cappel ◽  
Susanne Körsten ◽  
Christian B Fischer ◽  
Andreas Schönleber ◽  
...  
Keyword(s):  
Extracellular Polymeric Substances ◽  
Production Method ◽  
Wide Distribution ◽  
Time Dependent ◽  
Anabaena Cylindrica ◽  
Vegetative Cells ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
Dependent Growth ◽  
Average Size

Microbial biosynthesis of metal nanoparticles as needed in catalysis has shown its theoretical ability as an extremely environmentally friendly production method in the last few years, even though the separation of the nanoparticles is challenging. Biosynthesis, summing up biosorption and bioreduction of diluted metal ions to zero valent metals, is especially ecofriendly, when the bioreactor itself is harmless and needs no further harmful reagents. The cyanobacteriumAnabaena cylindrica(SAG 1403.2) is able to form crystalline Au0-nanoparticles from Au3+ions and does not release toxic anatoxin-a. X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and laser-induced breakdown spectroscopy (LIBS) are applied to monitor the time-dependent development of gold nanoparticles for up to 40 hours. Some vegetative cells (VC) are filled with nanoparticles within minutes, while the extracellular polymeric substances (EPS) of vegetative cells and the heterocyst polysaccharide layer (HEP) are the regions, where the first nanoparticles are detected on most other cells. The uptake of gold starts immediately after incubation and within four hours the average size remains constant around 10 nm. Analyzing the TEM images with an image processing program reveals a wide distribution for the diameter of the nanoparticles at all times and in all regions of the cyanobacteria. Finally, the nanoparticle concentration in vegetative cells ofAnabaena cylindricais about 50% higher than in heterocysts (HC). These nanoparticles are found to be located along the thylakoid membranes.

scholarly journals Molecular data reshape our understanding of the life cycles of three digeneans (Monorchiidae and Gymnophallidae) infecting the bivalve, Donax variabilis: it’s just a facultative host!

Parasite ◽  
2021 ◽  
Vol 28 ◽  
pp. 34
Author(s):  
Kristina M. Hill-Spanik ◽  
Claudia Sams ◽  
Vincent A. Connors ◽  
Tessa Bricker ◽  
Isaure de Buron
Keyword(s):  
Gulf Of Mexico ◽  
Intermediate Host ◽  
Atlantic Coast ◽  
The United States ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Larval Stages ◽  
Complete Life Cycle ◽  
Morphological Criteria ◽  
Donax Variabilis

The coquina, Donax variabilis, is a known intermediate host of monorchiid and gymnophallid digeneans. Limited morphological criteria for the host and the digeneans’ larval stages have caused confusion in records. Herein, identities of coquinas from the United States (US) Atlantic coast were verified molecularly. We demonstrate that the current GenBank sequences for D. variabilis are erroneous, with the US sequence referring to D. fossor. Two cercariae and three metacercariae previously described in the Gulf of Mexico and one new cercaria were identified morphologically and molecularly, with only metacercariae occurring in both hosts. On the Southeast Atlantic coast, D. variabilis’ role is limited to being a facultative second intermediate host, and D. fossor, an older species, acts as both first and second intermediate hosts. Sequencing demonstrated 100% similarities between larval stages for each of the three digeneans. Sporocysts, single tail cercariae, and metacercariae in the incurrent siphon had sequences identical to those of monorchiid Lasiotocus trachinoti, for which we provide the complete life cycle. Adults are not known for the other two digeneans, and sequences from their larval stages were not identical to any in GenBank. Large sporocysts, cercariae (Cercaria choanura), and metacercariae in the coquinas’ foot were identified as Lasiotocus choanura (Hopkins, 1958) n. comb. Small sporocysts, furcocercous cercariae, and metacercariae in the mantle were identified as gymnophallid Parvatrema cf. donacis. We clarify records wherein authors recognized the three digenean species but confused their life stages, and probably the hosts, as D. variabilis is sympatric with cryptic D. texasianus in the Gulf of Mexico.

Parthenogenesis and asexual multiplication among parasitic platyhelminths

Parasitology ◽  
1983 ◽  
Vol 86 (4) ◽  
pp. 121-160 ◽  
Author(s):  
P. J. Whitfield ◽  
N. A. Evans
Keyword(s):  
Stem Cells ◽  
Population Expansion ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Present Evidence ◽  
Stage Of Development ◽  
The Family ◽  
Asexual Multiplication ◽  
Modes Of Existence ◽  
First Intermediate Host

SUMMARYAmong flatworms with parasitic and commensal modes of existence, parthenogenesis and asexual multiplication appear to be largely confined to the Digenea and Cestoda, the only parasitic platyhelminths that routinely utilize indirect life-cycles. Parthenogenesis is apparently restricted to a minority of adult digeneans and cestodes inhabiting their final hosts, and a survey is made of the particular modes of parthenogenesis (i.e. apomictic, automictic and generative) which are employed by such adults. Asexual (amictic) multiplication, in the form of fissioning, is demonstrated by young adults of the cyclophyllidean cestode, Mesoces-toides corti, but is otherwise not exhibited by adult cestodes or digeneans, other than in the perplexing phenomenon of proglottid formation in polyzoic tapeworms. Secondary multiplication is of ubiquitous occurrence in digenean life-cycles in the form of the proliferation which takes place within sporocysts and rediae (germinal sacs) located in the first intermediate host. The controversy concerning the nature of this multiplication is reconsidered in the context of recent findings which have centred on cellular aspects. On the basis of present evidence germinal sac multiplication should be regarded as an asexual rather than a parthen-ogenetic process. The cestode asexual multiplication which occurs in intermediate hosts is a function of the metacestode stage of development. Metacestode proliferation is only known from about 20 species and 6 families of polyzoic cestodes with approximately half the described instances occurring in the family Taeniidae. The organization of these proliferative metacestodes, findings concerning their totipotent stem cells and the ontogeny of buds and new scolices are all reviewed. Finally, the capacity for population expansion of multiplicative larval digeneans and metacestodes are compared, while the ecological roles and the genetical consequences of both parthenogenesis and amictic multiplication in the two taxa are also examined.

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.

Checklist of the parasites of the black-necked swan, Cygnus melanocoryphus (Aves: Anatidae), with new records from Chile

Zootaxa ◽  
2010 ◽  
Vol 2637 (1) ◽  
pp. 55 ◽  
Author(s):  
DANIEL GONZÁLEZ-ACUÑA ◽  
LUCILA MORENO ◽  
ARMANDO CICCHINO ◽  
SERGEY MIRONOV ◽  
MIKE KINSELLA
Keyword(s):  
South America ◽  
Parasite Species ◽  
New Records ◽  
Southern Cone ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
New Host ◽  
Echinostoma Trivolvis ◽  
New Host Records

Black-necked swans (Cygnus melanocoryphus) are endemic to the southern cone of South America. Their range extends from Brazil and Paraguay south to Argentina and Chile. A total of 16 parasite species were collected from 7 swans from the Biobio region, Chile, of which 12 are new records for Chile and 11 represent new host records, Echinostoma trivolvis, Paranomostomum sp., Microsomacanthus sp., Nadejdolepis sp., Retinometra sp., Avioserpens sp., Capillaria skrjabini, Ingrassia cygni, Anatoecus penicillatus, A. icterodes and A. keymeri. A checklist is presented that summarizes sites of infections, localities, life cycles and their intermediate hosts (if known), and the pertinent references to demonstrate the wide diversity of parasites of black-necked swans. Our review of the existing literature (23 publications) along with our own records provided information on a total of 18 families and 27 genera, including 33 described species (some only identified to genus), of which 11 were recorded only in Chile (8 endoparasites and 3 ectoparasites), and 6 only in Argentina (4 endoparasites and 2 ectoparasites). Five parasites are known only from captive swans in European zoos. Parasites recorded from C. melanocoryphus include 23 helminths and 10 ectoparasites (one leech and 9 arthropods).

Host-based formation of fauna of lung helminths, its biological and taxonomic classification

2016 ◽  
Vol 3 (3) ◽  
pp. 345-369 ◽  
Author(s):  
Демиаскевич ◽  
A. Demiaszkiewiz ◽  
Мовсесян ◽  
S. Movsesyan ◽  
ПанайотоваПенчева ◽  
...  
Keyword(s):  
Species Composition ◽  
Family Life ◽  
Life Cycles ◽  
Land Snails ◽  
Taxonomic Classification ◽  
Intermediate Hosts ◽  
The Third ◽  
Object Of Study ◽  
Biological Group

Object of study: Studies of lung helminths from various groups were performed. Elaboration of biological and taxonomic classification of these species has been proposed. Materials and methods: 16 species from families Cervidae, Bovidae, Leporidae and humans were studied for lung helminths in Russia (South and central), Armenia, Bulgaria, Poland. The helminths found were studied using a scope of traditional and elaborated helminthological methods. Results and discussion: In lungs of mammals studied 23 helminth species have been found including 1 of Taeniidae (Echinococcus granulosus), 4 of Dictyocaulidae and 18 of Protostrongylidae. We have divided species composition of these lung helminths into three biological groups. The first biological group included nematodes from Dictyocaulidae family. Life cycles of those helminths are monoxenous (they are geohelminths). The second group includes helminths from family Protostrongylidae. Their life cycles include intermediate hosts — land snails and so they are dixenous (biohelminths). The third group includes an agent of a quite dangerous zoonosis — Echinococcus granulosis larvae. These cestodes also develop per dixenous type, but their intermediate hosts are vertebrates with definitive hosts also vertebrate, mostly carnivores. Taxonomic classification for family Protostrongylidae haelminths is also proposed.

Egg ultrastructure of the amabiliid cestode Tatria biremis Kowalewski, 1904 (Cyclophyllidea, Amabiliidae), with an emphasis on the oncospheral envelopes

2013 ◽  
Vol 58 (3) ◽  
Author(s):  
Vasyl Tkach ◽  
Zdzisław Świderski ◽  
Daniel Młocicki
Keyword(s):  
Cell Types ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Outer Envelope ◽  
Ultrastructural Studies ◽  
Egg Maturation ◽  
Ultrastructural Characteristics ◽  
Egg Envelopes ◽  
Host Infection ◽  
Inner Envelope

AbstractThis is the first report on the ultrastructure of eggs in the cestode family Amabiliidae Braun, 1900. The gravid proglottides of Tatria biremis easily detach from the strobila. Their thick-walled saccate uterus contains numerous rounded or oval eggs measuring about 30-32 μm in diameter. In the early preoncospheral phase, three primary embryonic envelopes are formed around the developing and differentiating embryos, namely: (1) vitelline capsule originating from vitellocyte material; (2) outer envelope formed by two macromeres, and (3) inner envelope originating from a fusion of three mesomeres. Thus, both the outer and inner envelopes of T. biremis eggs are cellular in origin and syncytial in nature. During egg maturation, the three primary embryonic envelopes undergo differentiation into fully formed oncospheral or egg envelopes. Most significant changes were observed in the inner envelope which becomes progressively subdivided into 3 sub-layers: the extra-embryophoral sub-layer, the embryophore, and the intra-embryophoral sub-layer, containing mesomere nuclei. The mature hexacanth is covered by a thin layer of the oncospheral tegument. Within the infective hexacanth larva, five cell types were distinguished: (1) a binucleated subtegumental cell; (2) U-shaped penetration gland; (3) nerve cells; (4) somatic cells representing the myocytons of both somatic and hook musculature, and (5) large germinative cells. Ultrastructural characteristics of T. biremis eggs are compared with those described in representatives of other cestode taxa. Since the functional ultrastructure of cestode egg envelopes is defined by multiple factors such as the type of life cycles, habitats and behaviour of the intermediate hosts, mode of the intermediate host infection, etc., ultrastructural studies of the greater diversity of cestodes are needed to obtain comparative data for fruitful analysis of cyclophyllidean cestode adaptations to their diverse life cycles.

Temperature-Dependent Growth and Production by a Marine Copepod

1981 ◽  
Vol 38 (1) ◽  
pp. 77-83 ◽  
Author(s):  
I. A. McLaren ◽  
C. J. Corkett
Keyword(s):  
Growth Rates ◽  
Life Cycles ◽  
Temperature Dependent ◽  
Marine Copepod ◽  
Development Times ◽  
Body Sizes ◽  
Eurytemora Herdmani ◽  
Growth Production ◽  
Dependent Growth ◽  
Specific Growth Rates

Highly synchronous cohorts of the copepod Eurytemora herdmani at a station near Halifax, Nova Scotia, were followed in samples taken during late July and early August, 1980. Individuals from the same population were reared in the laboratory from copepodite I (CI) to adult in conditions of food satiation. Development times and adult body sizes in nature were about the same as predicted for comparable temperatures in the laboratory. Weight increments between CI and adult male in samples from nature were exponential. Females became heavier, because of eggs, after CIII, but developed more slowly, so that their specific growth rates were about the same as for males. Production estimated from weights and stage increments in successive samples (cohort method) was adequately predicted from biomasses in samples and temperature-dependent development times from the laboratory. Production of egg matter by adult females was also adequately predicted by temperature-dependent growth rates of younger stages. These "rules" of development, growth, and production need wider empirical testing and theoretical justification.Key words: Copepoda, temperature, life cycles, development, growth, production

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