Variability in the prevalence of infection and cercarial production in Galba truncatula raised on a high-quality diet

Abstract

Two experiments using seven populations of Galba truncatula were carried out to analyse the effect of food quality (cos lettuce only, or cos lettuce+Tetraphyll) on the characteristics of infections: (1) in a single population of G. truncatula infected by one of three digenea (first experiment), and (2) in seven populations of G. truncatula differing in their susceptibility to Fasciola hepatica miracidia (second experiment). In most groups, food quality did not have a significant effect on the survival of snails. The prevalence of infection in five populations was significantly higher in snails raised on lettuce+Tetraphyll (first and second experiments), whereas it was close to those noted in lettuce only-reared groups in the last two populations (second experiment). Despite the higher growth of cercariae-shedding snails when raised on the mixed diet, no significant differences were noted. Significant effects of parasite species (first experiment) and of snail population (second experiment) on the life-spans of cercariae-shedding snails were noted, whereas food quality did not influence this parameter. Except for a single snail population, cercarial production in groups raised on lettuce+Tetraphyll was significantly higher than that in groups on lettuce. The variability noted in the prevalence of snail infections and in the intensity of cercarial shedding might be explained by differences in the susceptibility of snail populations to F. hepatica infections, and/or by the fact that Tetraphyll would not have the same appetency for all populations of G. truncatula.

A retrospective study on the metacercarial production of Fasciola hepatica from experimentally infected Galba truncatula in central France

“…Cos lettuce, which originated from a private garden, grown without chemical treatment, and used after a 5-day soaking in spring water, was utilized to feed G. truncatula. Since 2001, Tetraphyll (Tetrawerke, Melle, Germany) has been added every 3 days to cos lettuce in several experiments, based on 4.0 cm 2 of flake per box for 10 h (Rondelaud et al 2004). The use of this commercial fish food is based on the fact that it significantly increased metacercarial production of F. hepatica by stimulating cercarial shedding (Belfaiza et al 2004b;Rondelaud et al 2004).…”

“…Since 2001, Tetraphyll (Tetrawerke, Melle, Germany) has been added every 3 days to cos lettuce in several experiments, based on 4.0 cm 2 of flake per box for 10 h (Rondelaud et al 2004). The use of this commercial fish food is based on the fact that it significantly increased metacercarial production of F. hepatica by stimulating cercarial shedding (Belfaiza et al 2004b;Rondelaud et al 2004). These boxes were placed in an airconditioned room in the following conditions: constant temperature, 20±1°C; diurnal photophase, 12 h; light intensity over the boxes, 3,000-4,000 lx.…”

Efecto de la espirulina (Arthrospira platensis) (Oscillatoriales: Cyanobacteria) en la cría experimental de Pseudosuccinea columella (Basommatophora: Lymnaeidae)

“…As mentioned before, the quality of the diet provided as food for raising lymnaeid snails under laboratory conditions had a significant effect on their growth, fecundity and fertility, as well-fed snails became larger and laid more eggs (Rondelaud et al, 2004). Several studies have demonstrated that food quality determines a better snail development (Skoog, 1979), and it is generally accepted that when high quality food is available, lymnaeids will produce more eggs (Islam et al, 2001).…”

Fasciola hepatica: an unusual case of adaptation to a Moroccan population of Galba truncatula

“…After exposure, the snails were reared in polypropylene boxes 1 m·55 cm·15 cm high (40 snails per box). Leaves of romaine lettuce, used after 5 days in stagnant spring water, and commercial fish food (Tetraphyll, Tetrawerke, Melle, Germany), provided twice per week on the basis of 1.5-2.0 cm 2 of Tetraphyll flakes per box for 10 h (Rondelaud et al 2004b), were given as food for the snails. Each box contained small stones, with a 2-cm-deep layer of water, constantly aerated and changed once per week.…”