scholarly journals Parasite burden in decapod crustaceans from the central coast of Chile: is there any association with the relationship with definitive host abundances?

2017 ◽  
Vol 43 (4) ◽  
pp. 726-738
Author(s):  
Natalia Leiva ◽  
Mario George-Nascimento ◽  
Gabriela Muñoz
Keyword(s):  
Definitive Host ◽  
Parasite Burden ◽  
Life Cycles ◽  
Rocky Intertidal ◽  
Decapod Crustaceans ◽  
Intermediate Hosts ◽  
Rocky Intertidal Zone ◽  
The Family ◽  
Intertidal Habitats ◽  
The Relationship

Crustaceans play an important role in parasite life cycles, serving as second intermediate hosts. However, there are scarce parasitological studies in crustaceans from the rocky intertidal habitats, in Chile and around de world. In this study we aimed to record the parasites in decapod crustaceans, compare their parasitic loads between localities and relate them with the abundance of the definitive hosts (fishes and birds). Between July and September 2013, 409 crustacean specimens, corresponding to 16 species, were collected from the rocky intertidal zone of two localities of central Chile (33°S), Las Cruces and Montemar. Of out the sample, 65.5% was parasitized; counting 2,410 metacercariae and 18 nematodes. One group of these metacercariae belonged to the family Opecoelidae; while others corresponded to the family Microphallidae. Nematodes belonged to the family Cystidicolidae. The highest prevalence and abundance of opecoelids were in P. violaceus (96.9%, 13.59 ± 17.50 parasites/crustacean), microphallids were mostly recorded in the crab Petrolisthes tuberculosus (42.3%, 11.08 ± 4.8 parasites/crustacean), while cystidicolids were less prevalent and abundant than digenean at both localities. Parasite loads was affected by body size, locality and species of crustacean hosts. No association was found between parasite loads in these intermediate hosts and the abundance of definitive hosts. The low relationships between parasite loads and host abundances may be due to several reasons, such as a wide trophic spectrum and great capacity of movement, which would not contribute to the parasite transmission and the direct relationship with the definitive host abundances.

The Life Cycles of Dipetalonematid Nematodes (Filarioidea, Dipetalonematidae): The Problem of Their Evolution

1957 ◽  
Vol 31 (4) ◽  
pp. 203-224 ◽  
Author(s):  
Roy C. Anderson
Keyword(s):  
Life Cycle ◽  
Skin Lesion ◽  
Intermediate Host ◽  
Definitive Host ◽  
Life Cycles ◽  
The Body ◽  
Intermediate Hosts ◽  
Cutaneous Lesions ◽  
The Family ◽  
Subcutaneous Tissues

The evolution of the life cycles of the members of the family Dipetalonematiidae Wehr, 1935 (Filarioidea) is considered in the light of existing knowledge of spirurid nematodes. The hypothesis that the life cycles of the dipetalonematids originated from life cycles similar to those of Draschia megastoma, Habronema muscae and H. microstoma is considered to be incorrect. Alternatively, it is pointed out that in the primitive subfamily Thelaziinae Baylis and Daubney, 1926 there are forms with typical spiruroid life cycles (Rhabdochona ovifilamenta), forms with life cycles approaching those of the dipetalonematids (Thelazia spp.), and forms with life cycles intermediate between these two (Oxyspirura spp.). It is suggested that intestinal species similar to Rhabdochona gave rise to the more specialized spiruroids and forms that left the gut (Oxyspirura, Thelazia) gave rise to the dipetalonematids.The dipetalonematids are believed to have originated from nematodes resembling the species of Thelazia and having life cycles like those of T. rhodesii, T. skrjabini and T. gulosa. Some of these worms established themselves in subcutaneous tissues. Like Parafilaria multipapillosa, they released their eggs through a break in the skin of the definitive host, thus causing a skin lesion that attracted various haematophagous arthropods which finally became involved as intermediate hosts in the life cycle. Certain species like the members of Parafilaria and Stephanofilaria (?) came to rely upon intermediate hosts that were unable to break the skin of the definitive host (Musca) and cutaneous lesions became permanent features of their life cycles. Other species became dependent upon intermediate hosts that could puncture the skin (mosquitoes, simuliids etc.) and skin lesions became unnecessary to the life cycle. The larvae of these worms then began to spread into the tissues of the skin, as found in Stephanofilaria, Onchocerca, and some species of Dipetalonema, and the infective larvae developed the ability to penetrate into the wound made by the intermediate host and perhaps, in some cases, the intact skin. Ultimately the larvae of some species habitually entered, or were deposited into, the blood stream and the adult worms were then free to colonize the vertebrate body as their larvae would then be available to the intermediate host no matter where the latter fed on the body of the definitive host; this group of worms gave rise to the many members of the family Dipetalonematidae.The family Filariidae Claus, 1883 is briefly reviewed in the light of the above hypothesis. It is pointed out that many species, e.g. Diplotriaeninae Skrjabin, 1916, live in the air sacs of reptiles and birds and probably have life cycles similar to that of Diplotriaenoides translucidus, i.e. the eggs pass through the lungs, up the trachea and out in the faeces. It is thought that these forms may represent a separate line of evolution from that which gave rise to the Dipetalonematidae. Certain genera (Lissonema, Aprocta), occurring in the orbits of birds, probably have life cycles like Thelazia or Oxyspirura. Many other genera occurring in superficial muscles and subcutaneous tissues (Squamofilaria, Ularofilaria, Tetracheilonema, Pelecitus, Monopetalonema) may release their eggs through some sort of skin lesion. Studies on these forms are urgently needed as the details of their life cycles may shed fresh light on the origins of the more specialized filarioids.

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.

scholarly journals Cestodes of Antarctic and Subantarctic fish: History and prospects of research

2020 ◽  
Vol 5 (4) ◽  
pp. 79-93
Author(s):  
T. A. Polyakova ◽  
I. I. Gordeev
Keyword(s):  
Systematic Position ◽  
Life Cycles ◽  
Fish Parasites ◽  
Intermediate Hosts ◽  
Cestode Species ◽  
Dissostichus Mawsoni ◽  
The North ◽  
The Family ◽  
Muraenolepis Marmorata ◽  
High Level

The first information about cestodes of Antarctic and Subantarctic fish appeared at the beginning of the XX century: a cestode Phyllobothrium dentatum from an unknown shark was described. Peak of activity of studying Antarctic cestodes fell on 1990–2006. During this period, significant works were published, devoted to description of new species, their life cycles, host specificity of cestodes – fish parasites, and their geographical distribution. A notable contribution to the study of elasmobranch cestodes was made by a group of Polish scientists, headed by Wojciechowska (Rocka). Systematic position of 21 cestode species from 13 genera of 8 families of 6 orders was analyzed. Cestode fauna has been studied in less than 7 % of the total ichthyofauna of this area, while potential definitive and intermediate hosts remain unexplored. The largest number of cestode species (12) was recorded in four ray species of the family Rajidae. Eight cestode species, reaching sexual maturity, have been registered in intestines of teleosts: Bothriocephalus antarcticus, B. kerguelensis, Bothriocephalus sp., Parabothriocephalus johnstoni, P. macruri, Clestobothrium crassiceps, Neobothriocephalus sp., and Eubothrium sp. Larvae of five cestode species (Onchobothrium antarcticum, Grillotia (Grillotia) erinaceus, Lacistorhynchus tenuis, Calyptrobothrium sp., and Hepatoxylon trichiuri), ending their development in elasmobranchs, were found in teleosts. Systematic position of 5 cestode species out of 12, found in rays, is unidentified. Cestode fauna is characterized by a high level of endemism: 67 % of the total cestode fauna is not found to the north of Subantarctic. Coastal areas, mostly covered by research, are those in the Atlantic and Indian sectors of Antarctic. The biodiversity of elasmobranch cestodes, inhabiting Antarctic and Subantarctic, is underestimated, since only one third of species of these fish have been studied so far. Genetic studies of Antarctic cestodes have just begun to develop. Ribosomal sequences from D1–D3 segments of 28S rDNA are known only for 2 species: Onchobothrium antarcticum from the second intermediate (Notothenia rossii and Dissostichus mawsoni) and definitive hosts (Bathyraja eatonii), as well as larvae of Calyptrobothrium sp. from the second intermediate hosts (D. mawsoni and Muraenolepis marmorata). The main directions of further research on cestode fauna should be developed in combination with morphological, faunistic, genetic, and ecological studies.

Behaviours in trematode cercariae that enhance parasite transmission: patterns and processes

Parasitology ◽  
1994 ◽  
Vol 109 (S1) ◽  
pp. S3-S13 ◽  
Author(s):  
C. Combes ◽  
A. Fournier ◽  
H. Moné ◽  
A. Théron
Keyword(s):  
Definitive Host ◽  
External Environment ◽  
Life Cycles ◽  
Parasite Transmission ◽  
Intermediate Hosts ◽  
Larval Stages ◽  
Active Life ◽  
Host Life ◽  
Patterns And Processes ◽  
Almost All

Cercariae, like miracidia, are non-parasitic larval stages implicated in the life cycle of all trematodes for the host-to-host parasite transmission. Almost all cercariae are free-living in the external environment. With a few exceptions (cercariae of Halipegus occidualis (Halipegidae) can live several months, Shostak & Esch, 1990a), cercariae have a short active life during which they do not feed, living on accumulated reserves. Most cercariae encyst as metacercariae in second intermediate hosts which are prey of the definitive host; in certain species, the interruption of the active life is achieved by an encystment in the external environment (or a simple immobile waiting strategy in a few species). In some two-host life cycles, the cercariae develop into adults after penetration (this is the case for various species causing human schistosomiasis). Some cercariae do not leave the mollusc which must then be ingested by the definitive host.

Reproductive biology and population parameters of Petrolisthes laevigatus (Anomura: Porcellanidae) in southern Chile: consequences on recruitment

2007 ◽  
Vol 87 (3) ◽  
pp. 729-734 ◽  
Author(s):  
P. Gebauer ◽  
K. Paschke ◽  
C.A. Moreno
Keyword(s):  
Intertidal Zone ◽  
Adult Population ◽  
Reproductive Period ◽  
Rocky Intertidal ◽  
Southern Chile ◽  
Rocky Intertidal Zone ◽  
Intertidal Crab ◽  
Planktonic Larvae ◽  
Two Parameters ◽  
The Relationship

The present study describes the reproductive cycle and population structure of the intertidal crab Petrolisthes laevigatus, an abundant inhabitant of the upper rocky intertidal zone, as well as the relationship between seasonal patterns in the release of its planktonic larvae and recruiting. A total of 22900 individuals was collected along the coast of southern Chile between May 2001 and March 2003.The structure and density of the adult population (males and females) was relatively constant throughout the study period, although seasonal variations were observed in these two parameters of the benthic population (males, females, juveniles and megalopae), principally due to the incorporation of new individuals (recruitment) into the intertidal zone. Petrolisthes laevigatus presented a prolonged reproductive period. Females with initial eggs were present from the end of summer through to the middle of the following summer (11 months) and the breeding season lasted seven months (from August to February), as reflected in the six months of intertidal settlement (October–March).The interannual patterns and variations observed in the settlement along the southern Chilean coastline were related to the patterns in the abundance of potential released planktonic larvae. Petrolisthes laevigatus, unlike most temperate species, has a broad reproductive and settlement period in the south of Chile, which allows a highly stable structure and population abundance in this intertidal zone.

Intergenerational Family Relations in Luxembourg

2013 ◽  
Vol 18 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Isabelle Albert ◽  
Dieter Ferring ◽  
Tom Michels
Keyword(s):  
Family Relations ◽  
Family Values ◽  
Generation Gap ◽  
Intergenerational Solidarity ◽  
Acculturation Gap ◽  
Family Obligations ◽  
Mothers And Daughters ◽  
The Family ◽  
The Relationship ◽  
Model Family

According to the intergenerational solidarity model, family members who share similar values about family obligations should have a closer relationship and support each other more than families with a lower value consensus. The present study first describes similarities and differences between two family generations (mothers and daughters) with respect to their adherence to family values and, second, examines patterns of relations between intergenerational consensus on family values, affectual solidarity, and functional solidarity in a sample of 51 mother-daughter dyads comprising N = 102 participants from Luxembourgish and Portuguese immigrant families living in the Grand Duchy of Luxembourg. Results showed a small generation gap in values of hierarchical gender roles, but an acculturation gap was found in Portuguese mother-daughter dyads regarding obligations toward the family. A higher mother-daughter value consensus was related to higher affectual solidarity of daughters toward their mothers but not vice versa. Whereas affection and value consensus both predicted support provided by daughters to their mothers, affection mediated the relationship between consensual solidarity and received maternal support. With regard to mothers, only affection predicted provided support for daughters, whereas mothers’ perception of received support from their daughters was predicted by value consensus and, in the case of Luxembourgish mothers, by affection toward daughters.

Family Firms, Social Responsibility, and Non-Family Member Employees Identification

Think India ◽  
2013 ◽  
Vol 16 (3) ◽  
pp. 10-19
Author(s):  
Ang Bao
Keyword(s):  
Resource Allocation ◽  
Social Responsibility ◽  
Family Member ◽  
Program Implementation ◽  
Social Identity Theory ◽  
Family Firms ◽  
The Family ◽  
Corporate Social ◽  
The Relationship ◽  
Csr Engagement

The objective of this paper is to find the relationship between family firms’ CSR engagement and their non-family member employees’ organisational identification. Drawing upon the existing literature on social identity theory, corporate social responsibility and family firms, the author proposes that family firms engage actively in CSR programs in a balanced manner to increase non-family member employees’ organisational identification. The findings of the research suggest that by developing and implementing balanced CSR programs, and actively getting engaged in CSR activities, family firms may help their non-family member employees better identify themselves with the firms. The article points out that due to unbalanced CSR resource allocation, family firms face the problem of inefficient CSR program implementation, and are suggested to switch alternatively to an improved scheme. Family firms may be advised to take corresponding steps to select right employees, communicate better with non-family member employees, use resources better and handle firms’ succession problems efficiently. The paper extends employees’ identification and CSR research into the family firm research domain and points out some drawbacks in family firms’ CSR resource allocation while formerly were seldom noticed.

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