Parasitic infections in mixed system-based heliciculture farms: dynamics and key epidemiological factors

Abstract

Heliciculture is an excellent alternative to obtain edible snails but its viability is seriously threatened by pathogens. A parasitological survey was conducted in 3 mixed system-based heliciculture farms in Galicia (NW Spain), with the species Tetrahymena rostrata, Tetrahymena limacis, Tetratrichomonas limacis, Cryptobia helicogenae, Brachylaima aspersae (metacercariae and sporocysts), Alloionema appendiculatum, Nemhelix bakeri, and Riccardoella limacum being commonly found infecting Helix aspersa aspersa (petit-gris) snails. With the exception of C. helicogenae, N. bakeri, and B. aspersae sporocysts, all species were also detected in Helix aspersa maxima (gros-gris) snails, although generally with lower parameters. Most monoxenous infections, and consequently multiple parasitism, exhibited a rising trend during the first 2 months of intensive mating, with tendencies being slowed down or even reversed during the third month as a result of accumulated mortality and a sampling-derived reduction in host density. No parasites were vertically transmitted and infections were initially acquired from invading gastropod and micromammal reservoirs during fattening. Finally, artificial hibernation reduced significantly the prevalence of most species. These results confirm the importance of parasites in heliciculture and emphasize the need to prevent the entry of wild reservoirs into the farms and to rapidly remove the carcasses of dead snails from the reproduction units and fattening pens.

Morph-dependent nematode infection and its association with host movement in the land snail Cepaea nemoralis (Mollusca, Gastropoda)

“…Rae (2017) affirmed that encapsulation in the shell is specifically a response against nematode infection, drawing on the absence of other parasites across their large sample of shells; our results might contradict this affirmation. Riccardoella infection is highly variable across populations or species, with reported prevalences of 0% or near 0% being frequently observed (this study; Russo & Madec, 2013;Baur & Baur 2005;Segade et al 2013). Combined with the fact that encapsulation in the shell clearly has a success probability <1 (in our data, ≈ 22% of snails infected by nematodes at the time of the experiment showed no traces of nematode encapsulations; Data availability), this may explain why encapsulated mites were not previously found despite extensive surveys.…”

Import producten van dierlijke oorsprong : houderijaspecten en implicaties voor dierenwelzijn

“…Hoge bezettingen hebben een negatief effect op gezondheid en welzijn, wat terug te zien is een negatieve invloed op groei, voedselopname en voortplanting (Septer, 2002). Er komt een aantal ziektes voor -veroorzaakt door parasieten (nematoden en trematoden) en bacteriën (Pseudomonas) -die een serieuze bedreiging zijn voor gezondheid en welzijn van de slakken (Segade et al, 2013). Slakken in buitensystemen ondervinden een relatief hoge predatiedruk (Begg, 2003).…”

Intraspecies Variation in Tetrahymena rostrata

“…Tetrahymena rostrata (Kahl 1926, Corliss) are ciliated protozoa which can be free-living in edaphic environments [1][2][3][4][5] and can occur as facultative parasites of terrestrial molluscs [2,[6][7][8]. Most reports of natural infections of slugs and snails have shown that T. rostrata favours the renal tissues where it can multiply up to large numbers [8,9].…”