Morphogenesis of Contracaecum rudolphii (Nematoda: Ascaridoidea), a parasite of fish-eating birds, in its copepod precursor and fish intermediate hosts (original) (raw)

Parasite, 1996, 4, 367–376

Mémoire

Morphogenèse de Contracaecum Rudolphii (Nematoda : Ascaridoidea), parasite des oiseaux de mer, chez son hôte précurseur, le copépode, et son hôte intermédiaire, le poisson

Biology, University College of Cape Breton, PO Box 5300, Sydney, Nova Scotia, Canada B1P 6L2. Phone : 902-563-1624 — Fax : 902-562-0119 — e-mail : This email address is being protected from spambots. You need JavaScript enabled to view it. .

Received: 7 June 1996
Accepted: 8 August 1996

Abstract

Eggs of Controcaecum rudolphii obtained from female worms in double-crested cormorants (Phalacrocorax auritus) in Nova Scotia, Canada, hatched in 9-17 days in sea water at 15-20 °C. The newly-emerged, free-living (and presumably second-stage) larva is described in detail, as are larvae from experimentally-infected copepods (Tigriopus sp.), amphipods (Gammarus sp.), and fish (Lebistes reticulatus, Fundulus heteroclitus). Copepods are considered precursor hosts and morphogenesis of the parasite in them primarily involved body size, the ventricular appendix, and the excretory system. Infection of amphipods and fish was much more successful when invading larvae were from copepods than when they were free living; amphipods served as paratenic hosts and fish as intermediates. In fish, second-stage larvae 20 or fewer days postinfection were within the intestinal wall. At 44 or more days postinfection, larvae were considered third stage; all were in the abdominal cavity, many within a closely adhering « sleeve » of material resembling cuticle. The longest larvae (3,1-3.9 mm) in fish were associated with the oldest infection (152 d), suggesting that larvae continue to grow for a considerable period of time; growth was also found to be asynchronous, however.

Résumé

La larve de deuxième stade de Contracaecum rudolphii, de connaissance récente et vivant sans hôte, est décrite en détail ainsi que les larves venant de copépodes infectés en laboratoire (Trigriopus sp.), d'amphipodes (Gammarus sp.) et de poissons (Lebistes reticulatus, Fundulus heteroclitus). La morphogenèse du parasite dans le copépode, considéré comme hôte précurseur, inclut la taille, l'appendice ventriculaire et le système excrétoire. L'infection des amphipodes et des poissons est beaucoup plus importante lorsque les larves proviennent des copépodes que lorsqu'elles vivent sans hôte; les amphipodes ont servi d'hôtes paraténiques et le poisson d'hôte intermédiaire. Chez le poisson, les larves ont atteint le troisième stade 44 jours ou plus après l'infection; toutes se trouvaient dans la cavité abdominale, plusieurs à l'intérieur d'un « sac » étroitement ajusté et d'un matériau évoquant une cuticule. Chez le poisson, les larves les plus longues mesuraient de 3,1 à 3,9 mm (152 d). Il est probable que les larves continuent à grandir chez le poisson pendant une longue période mais la croissance en est cependant asynchrone.

Key words: nematode / parasite / Contracaecum spiculigerum / Ascaridoidea / morphogenesis / intermediate / paratenic / cormorant / bird

Mots clés : nématode / parasite / Contracaecum spiculigerum / Ascaridoidea / morphogenèse / intermédiaire / paraténique / cormoran / oiseau