Based on light and electron microscopical studies, a new nematode parasite, Echinocephalus inserratus sp. n. (Spirurida: Gnathostomatidae), is described from the spiral valve of the broad cowtail stingray Pastinachus ater (Macleay) (Dasyatidae, Myliobatiformes) from off New Caledonia. The new species is morphologically and biometrically most similar to Echinocephalus overstreeti Deardorff et Ko, 1983, differing from it mainly in the absence of serrations on the posterior parts of pseudolabia and on interlabia, and in having a longer gubernaculum (150-299 µm long). Morphologically unidentifiable, mostly encapsulated larvae of Echinocephalus spp. were recorded from the following six species of teleost fishes collected in New Caledonian waters, serving as paratenic hosts: Perciformes: Acanthopagrus berda (Forsskål) (Sparidae) and Nemipterus furcosus (Valenciennes) (Nemipteridae); Tetraodontiformes: Abalistes stellatus (Anonymous), Pseudobalistes fuscus (Bloch et Schneider) (both Balistidae), Lagocephalus sceleratus (Gmelin) (Tetraodontidae) and Aluterus monoceros (Linnaeus) (Monacanthidae). Co-parasitising larvae of Ascarophis sp. and Hysterothylacium sp. were also collected from P. fuscus. All these findings represent new host and geographical records. A key to valid species of Echinocephalus Molin, 1858 is provided.
The larval development of the nematode Contracaecum rudolphii (Rudolphi, 1819), a common parasite of the proventriculus of cormorants, was experimentally studied. Within the eggs cultivated in freshwater under laboratory temperatures of 20-22 °C, the developing larva undergoes two moults on days 4-5, attaining the third larval stage. Most of the ensheathed third-stage larvae, 291-457 µm long, hatch spontaneously from egg shells on days 5-6. Experiments have indicated that hatched ensheated third-stage larvae and those still inside egg capsules are already infective to copepods and fishes, which both can be considered paratenic (metaparatenic) hosts. Five copepod species, Acanthocyclops vernalis, Cyclops strenuus, Ectocyclops phaleratus, Eucyclops serrulatus and Megacyclops viridis, the isopod Asellus aquaticus and small carps Cyprinus carpio were infected by feeding them these larvae. In addition, 9 fish species, Alburnoides bipunctatus, Anguilla anguilla, Barbatula barbatula, Cyprinus carpio, Gobio gobio, Perca fluviatilis, Phoxinus phoxinus, Poecilia reticulata and Tinca tinca, were successfully infected by feeding them copepods previously infected with C. rudolphii third-stage larvae. In fishes, larvae from copepods penetrate through the intestinal wall to the body cavity, where, in a few weeks, they become encapsulated; the larvae substantially grow in fish, attaining the body length up to 4.87 mm. In carp fry, the nematode third-stage larvae survived for about 15 months (up to 18 months in fish infected directly, i.e., without copepods). One small cormorant (Phalacrocorax carbo sinensis) was successfully infected by feeding it with copepods harbouring C. rudolphii third-stage larvae.
Four laboratory-hatched European kestrels Falco tinnunculus L. were fed on laboratory mice and common voles Microtus arvalis Pallas previously inoculated with different doses of sporulated oocysts of Caryospora kutzeri Böer, 1982. Two kestrels that were fed infected mice shed C. kutzeri oocysts 6 days after ingesting murine tissues. To compare direct and indirect transmissions, two of the kestrels were subsequently directly inoculated with 105 sporulated C. kutzeri oocysts and became patent on days 8 and 9 and shed caryosporan oocysts up to day 25 post inoculation. Additionally, four mice were inoculated with 106 oocysts in order to examine mouse tissues for the presence of developmental stages of C. kutzeri. No coccidian stages were found in the tissues of inoculated mice. The experiment showed that developmental stages of C. kutzeri are able to survive in mouse tissues and cause infection of suitable host after their ingestion.
Here, we present the ITS ribosomal DNA (rDNA) sequence data on 330 larvae of nematodes of the genus Anisakis Dujardin, 1845 collected from 26 different bony fish species from 21 sampling locations and different climatic zones. New host records are provided for Anisakis simplex (Rudolphi, 1809) sensu stricto (s.s.) and A. pegreffii Campana-Rouget et Biocca, 1955 from Anoplopoma fimbria (Pallas) (Santa Barbara, East Pacific), A. typica (Diesing, 1860) from Caesio cuning (Bloch), Lepturacanthus savala (Cuvier) and Katsuwonus pelamis (Linnaeus) (Indonesia, West Pacific), A. simplex s.s. from Cololabis saira (Brevoort) (Hawaii, Central Pacific), A. simplex C of Nascetti et al. (1986) from Sebastolobus alascanus Bean (Santa Barbara, East Pacific) and A. physeteris Baylis, 1923 from Synaphobranchus kaupii Johnson (Namibia, East Atlantic). Comparison with host records from 60 previous molecular studies of Anisakis species reveals the teleost host range so far recorded for the genus. Perciform (57 species) and gadiform (21) fishes were the most frequently infected orders, followed by pleuronectiforms (15) and scorpaeniforms (15). Most commonly infected fish families were Scombridae (12), Gadidae (10), Carangidae (8) and Clupeidae (7), with Merluccius merluccius (Linnaeus) alone harbouring eight Anisakis species. Different intermediate host compositions implicate differing life cycles for the so far molecularly identified Anisakis sibling species.
Caryospora duszynskii Upton, Current et Barnard, 1984 was successfully transmitted to snakes of the genus Elaphe by feeding them previously infected mice. Fifty thousand oocysts were orally administered to two mouse strains, BALB/c and Crl:CD-1(ICR)BR, which were subsequently fed to captive-born coccidia-free Elaphe guttata (L.) in two respective independent experiments. Both E. guttata expelled C. duszynskii oocysts in their faeces, beginning on day 18 and 26 post infection (p.i.) and shed oocysts continuously through the end of the experiment, day 230 and 135 p.i., respectively. There were no parasitic stages or lesions in mice, as revealed by histological examination. Experiments proved that rodents serve as paratenic hosts for C. duszynskii. In summary we discuss the life-cycle strategies of Caryospora spp. in reptiles and present three general modes of their development.
The development of the nematode Syncuaria squamata (Linstow, 1883), a gizzard parasite of cormorants, was experimentally studied in the ostracod Notodromas monacha. After the eggs of this nematode have been swallowed by the ostracod, the toothed first-stage larvae of the parasite are released and penetrate through the intestinal wall into the haemocoel of the crustacean. Before attaining the infective third stage, the larvae moult twice in the body of the intermediate host (9-11 and 13-15 days after infection at water temperatures of 20-22° C). The fishes Alhumaides hipunctatus, Noemacheilus barbatulus, Oncor-hynchus mykiss and Poecilia reticulata were for the first time recorded as suitable experimental paratenic hosts of S. squamata third-stage larvae in which a slight growth of larvae may occur. The first recorded natural paratenic host of this nematode was tench, Tinca tinea, originating from a South-Bohemian pond where cormorants occur. Paratenic hosts are apparently the main source of S. squamata infection for cormorants.
Three species of planktonie crustaceans, Cyclops strenuus and Macrocyclops alhidus (Copcpoda) and Notodromas monacha (Ostracoda), were experimentally infected with the eggs and second-stage larvae of the swimbladder nematode Anguillicola crassus originating from eels from Neusiedler Lake in Austria. At 20-22°C, third-stage larvae of the parasite developed in all these invertebrate hosts within 16-20 days p.i. Ostracods harbouring the nematode third-stage larvae (33 days p.i.) were fed to small eels (Anguilla anguilla), while infected copepods (20 days p.i.) to seven other fish species. By these experiments, the larvae from ostracods proved to be infective for the definitive host and the ostracod was thus confirmed as a true intermediate host of Anguillicola crassus. Notodromas monacha represents a new experimental intermediate host of A. crassus and the second known invertebrate other than a copepod in which the larval development of this nematode up to the infective stage takes place. Five species of fish, cyprinids Tinca tinea, Alhumus alburnus, Gobio gobio and Albumoides bipunctatus (the latter representing a new host record), and guppy, Poecilia reticulata, were found to serve as experimental paratenic hosts for A. crassus, in which the live nematode infective larvae were recorded 49 days p.i.