Morphological, developmental and ecological evidence for a progenetic life cycle in Neochasmus (Digenea)

Abstract

Abstract. Seven species of fishes, Catostomus commersonii (Lacépède), Etheostoma nigrum Rafinesque, Micropterus dolomieu Lacépède, Notemigonus crysoleucas (Mitchill), Notropis hudsonius (Clinton), Perca flavescens (Mitchill), and Percina caprodes (Rafinesque) from the St. Lawrence River, Quebec, Canada, were found infected with progenetic specimens of Neochasmus spp. in the orbits and/or the body musculature. Worms displayed varying degrees of maturation. Eggs occupied the entirety of the worm in late stages of development and persisted as distinct clusters in situ after worm death. Populations of parasites were studied monthly in E. nigrum from one site between May and October in order to follow parasite recruitment, development and maturation. Recruitment of parasites was observed in young-of-the-year fish

Encystment site affects the reproductive strategy of a progenetic trematode in its fish intermediate host: is host spawning an exit for parasite eggs?

“…In contrast, progenetic worms found elsewhere have to wait for the bully host to die, either naturally followed by decay or through predation, to be released into the environment (Poulin and Cribb, 2002; McLaughlin et al . 2006). However, fish spawning should not equally affect all worms throughout the host but only those found in the gonads.…”

Autonomy and integration in complex parasite life cycles

“…However, this limits the ability of worms to reproduce, because they are faced with the problem of how to release eggs into the external environment. One solution is to rely on intermediate host death, often via predation, to liberate gravid worms stuck in the tissues (Pampoulie et al 2000; McLaughlin et al 2006), another is to migrate into the host's gut (Corkum and Beckerdite, 1975). Progenetic individuals of the aforementioned trematode S. anguillae occupy the gonads of its fish host and are released into the environment when the fish spawn (Herrmann and Poulin, 2011 a ).…”

The invasive round goby Apollonia melanostoma (Actinopterygii: Gobiidae) - a new intermediate host of the trematode Neochasmus umbellus (Trematoda: Cryptogonimidae) in Lake Erie, Ohio, USA

“…and darters Etheostoma spp. are the most common hosts of metacercariae (Muzzall and Peebles, 1987; McLaughlin et al., 2006). The metacercariae often are found in many other smaller‐sized fishes, but rarely occur in predatory fishes, such as yellow perch Perca flavescens (Mitchill, 1814) and smallmouth bass Micropterus dolomieu (Carney and Dick, 2000; McLaughlin et al., 2006).…”

“…Adult N. umbellus are commonly found in piscivorous fishes [e.g. the least darter Etheostoma microperca Jordan and Gilbert, 1888; tessellated darter E. olmstedi Storer, 1842; smallmouth bass Micropterus dolomieu Lacépède, 1802; white perch Morone americana (Gmelin, 1789); white bass M. chrysops (Rafinesque, 1820); and yellow bass M. mississippiensis Jordan and Eigenmann, 1887] (Muzzall and Peebles, 1987; Dechtiar and Christie, 1988; Dechtiar and Nepszy, 1988; McLaughlin et al., 2006). The first intermediate host of this parasite is unknown.…”

“…The first intermediate host of this parasite is unknown. A progenetic life cycle, in which the reproductive organs of the parasite develop during the metacercariae stage (Poulin and Cribb, 2002), is typical for N. umbellus (McLaughlin et al., 2006).…”