The life cycle of Anguillicola crassus

Abstract

For some years now the parasitic swim bladder nematode Anguillicola crassus of the European eel Anguilla anguilla L., has been reported from several European countries. The enhre life history of this parasite has recently been elucidated in our laboratory. Young larvae leave the swim bladder of the host via the pneumatic duct and reach the water through the digestive tract. They are ingested by small copepods (Cyclopoida), which act as intermediate hosts. Larvae remain in the hemocoel until the copepods are eaten by the final host, the European eel. Larvae penetrate through the intestinal wall and reach the swim bladder where they develop into adults. When infected copepods are eaten by other small fish, such as carp Cyprinus carpio L. or ide Leuciscus idus L., larvae do not reach the adult stage. However, when larger eels feed on such facultative reservoir hosts, they too become infected.

Macroparasite communities in European eels,Anguilla anguilla, from French Mediterranean lagoons, with special reference to the invasive speciesAnguillicola crassusandPseudodactylogyrusspp.

“…Small eels generally feed on small prey such as crustaceans, and progressively become piscivorous as their size increases (Tesch, 2003). Anguillicola crassus has a complex life cycle that includes one obligatory intermediate host, usually copepods (De Charleroy et al, 1990), and one non-obligatory paratenic host, usually small fishes (Thomas and Ollevier 1992a;Székely, 1994). Therefore, our result suggests that transmission rates of A. crassus by paratenic hosts may be lower than by intermediate hosts in Mediterranean lagoons.…”

Étude sur la biologie des premiers stades larvaires d'Anguillicola crassus (Nematoda, Dracunculoidea) : spécificité de l'hôte intermédiaire et influence de la température sur la durée du développement

“…Depuis l'introduction il y a quelques années et la rapide extension de l'espèce Anguillicola crassus chez les anguilles européennes (Anguilla anguilla L.), de nombreux Article available at http://www.kmae-journal.org or http://dx.doi.org/10.1051/kmae:1991010 travaux ont été effectués aussi bien sur l'action pathogène de ces Nématodes (BLANC, 1989 ;BLANC et al, 1990) que sur leur biologie et leur cycle évolutif complet a été réalisé en laboratoire (De CHARLEROY et al, 1990 ;BONNEAU, 1990). Cependant, la plupart des expériences d'infestation de l'hôte intermédiaire ont été réalisées avec des Copépodes (ainsi, DE CHARLEROY et al, 1987, ont obtenu l'infestation de 10 espèces de Cyclopidae, alors que 2 espèces d'Harpacticoida ne se sont pas infestées), et peu d'auteurs ont tenté l'infestation d'autres Invertébrés.…”

Pratenic hosts of the swimbladder nematode Anguillicola crassus

“…made no mention of the occurrence of paratenic hosts (Hirose et al 1976, Wang & Zhao 1980, Huang 1981, Kim et al 1989. In Europe there are some reports on the occurrence of Anguillicola crassus larvae in various fish species other than eels (De Charleroy et al 1990, Haenen & van Banning 1990 and the possibility of the transfer of L3-larvae from experimentally infected ide and carp to eel was proven by De Charleroy et al (1990) and for L3-larvae from smelt and ruffe by Haenen & van Banning (1991).…”

“…The life cycle of Anguillicola crassus in the European eel Anguilla anguilla L. has been studied by De Charleroy et al (1990). The adult nematode lives in the swimbladder lumen.…”

“…The eggs, which contain L2-larvae at oviposition or hatched L2-larvae, reach the water after passage through the pneumatic duct and the intestine. When L2-larvae are ingested by freshwater cyclopoid copepods they develop in the haemocoel to the third infective stage (L3) (De Charleroy et al 1990). These larvae are infective to eels; however, since copepods are not considered a major food item for eels and because eels larger than 50 cm feed almost exclusively on fish (Tesch 1977, de Nie 1988 it was reasonable to assume that other fish species might act as a paratenic host (= reservoir host) for Anguillicola cras-…”