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.

Cost of interspecific competition between trematode colonies

2020 ◽  
Vol 94 ◽  
Author(s):  
K.N. Mouritsen ◽  
C.K. Elkjær
Keyword(s):  
Intermediate Host ◽  
Interspecific Competition ◽  
Parasite Species ◽  
Division Of Labour ◽  
The Other ◽  
Trematode Species ◽  
Littorina Littorea ◽  
Fitness Costs ◽  
Species Specific ◽  
First Intermediate Host

Abstract In a range of trematode species, specific members of the parthenitae colony infecting the molluscan first intermediate host appear specialized for defence against co-infecting species. The evolution of such division of labour requires that co-infection entails fitness costs. Yet, this premise has very rarely been tested in species showing division of labour. Using Himasthla elongata (Himasthlidae) and Renicola roscovita (Renicolidae) infecting periwinkles Littorina littorea as study system, we show that the size of emerged cercariae is markedly reduced in both parasite species when competing over host resources. Cercarial longevity, on the other hand, is negatively influenced by competition only in R. roscovita. Season, which may impact the nutritional state of the host, also affects cercarial size, but only in H. elongata. Hence, our study underlines that cercarial quality is, indeed, compromised by competition, not only in the inferior R. roscovita (no division of labour) but also in the competitively superior H. elongata (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.

Studies on the life-cycle ofHimasthla militaris(Trematoda: Echinostomatidae): influence of temperature and salinity on the life-span of the miracidium and the infection of the first intermediate host,Hydrobia ventrosa

Parasitology ◽  
1982 ◽  
Vol 84 (1) ◽  
pp. 131-135 ◽  
Author(s):  
R. Vanoverschelde
Keyword(s):  
Life Cycle ◽  
Life Span ◽  
Intermediate Host ◽  
Half Life ◽  
Snail Host ◽  
Influence Of Temperature ◽  
First Intermediate Host

SUMMARYThe influence of temperature and salinity on miracidial longevity and miracidial infectivity of the digenean,Himasthla militaris, has been examined. At 14, 25 and 30 °C the half-life of the miracidia was 1200, 630 and 420 min respectively, and infection of the first intermediate host,Hydrobia ventrosa, only occurred at 25 and 30 °C, for both temperatures 52% became infected. In the range 2·1 to 34‰ (2·1, 4·2, 8·5, 17 and 34‰) the miracidia had a minimal and maximal half-life of 60 and 630 min in water with a salinity of 2·1 and 17‰ respectively, while the infection of the snail host was possible only in water with a salinity of 8·5 and 17‰.

Hymenolepis diminuta: an investigation of juvenile hormone titre, degradation and supplementation in the intermediate host, Tenebrio molitor

Parasitology ◽  
1990 ◽  
Vol 100 (3) ◽  
pp. 445-452 ◽  
Author(s):  
H. Hurd ◽  
C. Strambi ◽  
N. E. Beckage
Keyword(s):  
Juvenile Hormone ◽  
Intermediate Host ◽  
Topical Application ◽  
Post Infection ◽  
Reproductive Output ◽  
Endocrine System ◽  
Tenebrio Molitor ◽  
Hymenolepis Diminuta ◽  
Significant Difference ◽  
Female Control

SUMMARYMetacestodes of Hymenolepis diminuta cause a perturbance of vitellogenesis in the intermediate host Tenebrio molitor. The reduction in host reproductive output associated with infection may be due to this pathophysiology. Many of these events are regulated by host juvenile hormone (JH). A comparison of the titre of JH and its rate of degradation in female control and parasitized 15-day-old insects has been made. Haemolymph from female beetles contained 1·27 pMol JH equivalents/100 µl. No significant difference was associated with infection. However, topical application of a JH analogue, methoprene, at the time of infecion or 8 days post-infection reduced the significant accumulation of vitellogenin usually found in the haemolymph of females 12 days or more post-infection. These findings indicate that parasite-induced alteration of host vitellogenesis is not mediated via alteration in JH titres, although observations made after hormone supplementation suggest some form of interaction between the parasite and the host endocrine system.

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