Extensive Abnormalities in Larval Trematode Infection

1961 ◽  
Vol 47 (3) ◽  
pp. 445
Author(s):  
Kathleen L. Hussey ◽  
Walter B. Stahl
Keyword(s):  
Larval Trematode ◽  
Trematode Infection

Polymorphism in Velacumantus australis (Gastropoda : Potamididae) and its relationship to parasitism

1966 ◽  
Vol 14 (1) ◽  
pp. 49 ◽  
Author(s):  
WH Ewers ◽  
CR Rose
Keyword(s):  
Lower Incidence ◽  
Sexual Maturity ◽  
Age Groups ◽  
Larval Trematode ◽  
Trematode Infection ◽  
Balanced Polymorphism

Velacumantus australis is a common gastropod along the Australian coast. Samples of four populations were examined and the frequency of two banded forms was recorded. All brown-banded snails were small juveniles and these apparently die before reaching adolescence. White-banded snails occurred in all age groups and their frequency tends to be highest in juveniles and lowest in the oldest adults. White-banded snails have a much lower incidence of larval trematode infection than unbanded snails and also differ slightly in weight and in the onset of sexual maturity. It is suggested that these forms are maintained as a selectively balanced polymorphism.

Selection pressures and polymorphisms in Velacumantus australis (Quoy & Gaimard)

1967 ◽  
Vol 15 (4) ◽  
pp. 727 ◽  
Author(s):  
WH Ewers
Keyword(s):  
Larval Trematode ◽  
Selection Pressures ◽  
Trematode Infection ◽  
Different Populations ◽  
Resistance To Infection

Populations of Velacumantus australis from the Australian mainland are polymorphic for white-bandedness. The frequency of banded snails in a number of different populations is higher in small juveniles than in older snails, which suggests that the same kinds of selection pressures may be maintaining the polymorphism in different populations. Selection pressures due to parasitism and predation by boring gastropods and fish act differentially on banded and unbanded snails. Banded snails are less often infected with larval trematodes than unbanded snails. These infections cause either complete castration or considerable degeneration of the gonads. The significance of this resistance to infection is discussed. On theoretical grounds there should be a relationship between the incidence of larval trematode infection and the frequency of banded snails. Data from a number of populations suggest that there is such a relationship. Selection pressures other than those due to parasitism and predation probably play a part in the maintenance of the polymorphism.

Larval Trematode Infection in Juveniles and Adults of Physa parkeri Currier

1941 ◽  
Vol 27 (2) ◽  
pp. 123 ◽  
Author(s):  
William W. Cort ◽  
Louis Olivier ◽  
D. B. McMullen
Keyword(s):  
Larval Trematode ◽  
Trematode Infection
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