Influence of cadmium exposure on the incidence of first intermediate host encystment by Echinoparyphium recurvatum cercariae in Lymnaea peregra

2004 ◽  
Vol 78 (4) ◽  
pp. 329-332 ◽  
Author(s):  
N.J. Morley ◽  
M. Crane ◽  
J.W. Lewis
Keyword(s):  
Intermediate Host ◽  
Metal Accumulation ◽  
Cadmium Exposure ◽  
Parasite Transmission ◽  
Body Tissues ◽  
Lymnaea Peregra ◽  
First Intermediate Host

AbstractThe effect of cadmium exposure of the snail first intermediate host Lymnaea peregra on the incidence of encystment of Echinoparyphium recurvatum (Digenea: Echinostomatidae) cercariae without emergence from the snail was investigated. Exposure to 100 μg l−1 Cd for 72 h caused a significant increase in the incidence of first host encystment when compared to controls. In addition, autometallographic staining of E. recurvatum daughter rediae and developing cercariae showed that there was metal accumulation within their body tissues. The significance of these findings to parasite transmission in metal-polluted environments is discussed.

Phototactic responses of the cercaria of Echinoparyphium recurvatum during phases of sub-maximal and maximal infectivity

1999 ◽  
Vol 73 (1) ◽  
pp. 63-65 ◽  
Author(s):  
A.M. McCarthy
Keyword(s):  
Intermediate Host ◽  
First Record ◽  
Dark Side ◽  
Choice Chamber ◽  
Lymnaea Peregra ◽  
Light Side ◽  
First Intermediate Host

Phototactic responses of cercariae of the echinostome Echinoparyphium recurvatum (Digenea: Echinostomatidae) were investigated during phases of sub-maximal and maximal infectivity using a simple light/dark choice chamber. The phototactic responses of a total of 400 cercariae were examined in 20 replicate experiments during their sub-maxinal infectivity dispersal phase (0.5 h post-emergence from the first intermediate host Lymnaea peregra) and during their maximal infectivity phase (2.5 h post-emergence). Cercariae in the sub-maximal infectivity dispersal phase were found to be positively phototactic, significantly larger numbers of them occurring on the light side of a light/dark choice chamber P < 0.001. Cercariae in the maximal infectivity phase were found to be negatively phototactic, significantly larger numbers of them being found on the dark side of the choice chamber, P < 0.001. This report of ‘phototactic switching’ demonstrated by the cercariae of E. recurvatum from a positively phototactic dispersal phase to a negatively phototactic infection phase constitutes the first record of such behaviour in the cercaria of an echinostome.

The Influence of Various Definitive Hosts on the Development ofDiplostomum phoxini(Strigeida, Trematoda)

1960 ◽  
Vol 34 (3-4) ◽  
pp. 205-210 ◽  
Author(s):  
A. D. Berrie
Keyword(s):  
Intermediate Host ◽  
Host Specificity ◽  
Host Species ◽  
Freshwater Snail ◽  
Herring Gull ◽  
Lymnaea Peregra ◽  
First Intermediate Host

.1. Infection withDiplostomulum phoxiniis very common among minnows in the Glasgow area of Scotland.2. The first intermediate host of the parasite in this area is shown to be the freshwater snailLymnaea peregra.3. Adult flukes were obtained experimentally in mice, ducklings and herring-gull chicks.4. Significant differences are shown to occur between adult flukes recovered from different host species.5. The implications of these findings in relation to the host specificity and the classification of the Strigeida are briefly discussed.

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.

Life cycle studies on two Digenea, Paradistomum geckonum (Dicrocoeliidae) and Mesocoelium sociale (Mesocoeliidae), in geckonid lizards from Indonesia

1987 ◽  
Vol 65 (10) ◽  
pp. 2491-2497 ◽  
Author(s):  
Murray J. Kennedy ◽  
L. M. Killick ◽  
M. Beverley-Burton
Keyword(s):  
Life Cycle ◽  
Intermediate Host ◽  
Intermediate Hosts ◽  
Larval Stages ◽  
Hemidactylus Frenatus ◽  
Pulmonate Gastropod ◽  
First Intermediate Host

Life cycle studies of Paradistomum geckonum (Dicrocoeliidae) were attempted experimentally. The pulmonate gastropod Lamellaxis gracilis served as the first intermediate host; geckonid lizards (Cosymbotus platyurus, Gehyra mutilata, and Hemidactylus frenatus) served as definitive hosts. The life cycle of Mesocoelium sociale (Mesocoeliidae) was studied in naturally infected first intermediate hosts (L. gracilis, Huttonella bicolor) and experimentally in geckonid definitive hosts (C. platyurus, G. mutilata, and H. frenatus). Some naturally infected L. gracilis were infected concurrently with larval stages of both digeneans. Second intermediate hosts, presumed to be arthropods, were experimentally unnecessary. Metacercariae of P. geckonum were not found. Cercariae of M. sociale formed encysted metacercariae in the same individual snails.

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