Clearcutting and deforestation lead to increased erosion, increased water temperature, altered water chemistry, and modified watershed hydrology in aquatic systems. Effects on biological organisms have been documented for phytoplankton, zooplankton, benthos, and fish. In this study, parasites of the northern redbelly dace, Phoxinus eos (Cope), were examined from an experimental area consisting of headwater lakes and their watersheds in the boreal forest of Ontario, Canada prior to and after clearcutting around the lakes. Catchments of two lakes were heavily, and one lake partially, clearcut in 1996, and that of a fourth lake was untouched. In 1993, three years prior to clearcutting, five taxa of parasites, including the monogeneans Dactylogyrus sp. and Gyrodactylus sp., metacercaria of the digenean Clinostomum complanatum (Rudolphi, 1819), the nematode Rhabdochona canadensis Moravec et Arai, 1971 and the myxozoan Myxobolus sp. were found in or on northern redbelly dace. In 1998, two years after clearcutting, eight taxa were found on northern redbelly dace, including all of the above plus the digeneans Allocreadium sp. and Ornithodiplostomum ptychocheilus (Faust, 1917) and the copepod Ergasilus lizae Krøyer, 1863. Mean infracommunity species richness and the maximum number of species per fish were higher in the control and partially cut lake than in the heavily logged lakes. Uninfected fish were found in the heavily cut lakes, but not in the other lakes. Thus, disturbance may reduce parasite infracommunity complexity. Among individual parasite species, R. canadensis was absent from the two most heavily clearcut lakes and abundant in the two other lakes in 1998. Clearcutting may have affected the abundance of certain invertebrates in these lakes, in particular the mayflies that serve as intermediate hosts for R. canadensis. The parasites Allocreadium sp., O. ptychocheilus, and E. lizae have not been previously reported in or on northern redbelly dace.
Some free-living amoebae are a potential threat to human health. The best known species are those of the genus Acanthamoeba Volkonsky, 1931, which cause Acanthamoeba keratitis, granulomatous amoebic encephalitis and other forms of tissue inflammation. The aim of the present study was to search for potential pathogenic genotypes of free-living amoeba in the sand in children's playgrounds. Our results confirmed that free-living amoebae were present in all examined playgrounds. Sequences of the 18S rDNA have shown that all isolated potentially pathogenic strains of amoebae belong to genotype T4 of Acanthamoeba. The potential pathogenicity of isolates was confirmed on mice. The presence of pathogenic amoebae in the examined sand may be a potential source of human infection., Marcin Cholewiński, Piotr Solarczyk, Monika Derda, Agnieszka Wojtkowiak-Giera, Edward Hadaś., and Obsahuje bibliografii
A new species of Prochristianella Dollfus, 1946 is described from the spiral intestine of the wedgenose skate, Dipturus whitleyi (Iredale) (Rajiformes: Rajidae), off the north-western coast of Tasmania (Australia). Prochristianella mattisi sp. n. is characterised by an acraspedote scolex, two oval bothria, elongate, bent bulbs, a retractor muscle inserting at the base of each bulb and the presence of gland-cells within the bulbs and prebulbar organs. The tentacular armature is typical heteroacanthous, heteromorphous, with a characteristic basal oncotaxy and a metabasal armature with hooks first increasing and then decreasing in size along each principle row. It can be differentiated from other species of Prochristianella by a combination of morphological characters, such as the metabasal tentacular armature with eight hooks per principle row, a unique basal armature without enlarged hooks on the basal swelling and genital pores slightly posterior to the mid-line of the segment. The description of P. mattisi sp. n. increases the number of known species within Prochristianella to 20, eight of which occur in Australian waters. A key for the identification to species within Prochristianella is provided.
Pseudocapillaria moraveci sp. n. (Nematoda, Capillariidae) is described from the stomach of Gobius paganellus Linnaeus (Perciformes, Gobiidae) from rocky shores of the Vigo estuary (Northwest Atlantic coast of Spain). Scanning electron microscopy reveals the absence of a dorsal cuticular membrane interconnecting the caudal lobes of male, thus confirming the assignment of this new species to the nominotypical subgenus Pseudocapillaria Freitas, 1959. Pseudocapillaria moraveci can be easily differentiated from other marine congeneric species belonging to subgenera Pseudocapillaria and Ichthyocapillaria Moravec, 1982 by its muscular oesophagus, which is distinctly thickened at the distal third, the terminal or almost terminal anus in female, the presence of a basal internal papilla on each ventrolateral caudal lobe in male, and its exclusive site preference for the stomach. In addition, the spicule, which measures 0.180-0.292 mm in length (4.9-7.9% of body length) and possesses a proximal end expanded and oblique in lateral view, a narrowed middle part, and a distal end almost pointed, also distinguishes this species. Pseudocapillaria moraveci is, together with P. tomentosa (Dujardin, 1843) Moravec, 1987, the only species in the genus Pseudocapillaria that has been reported to infect members of the family Gobiidae.
In the last decade a great effort has been devoted in animal evolutionary ecology to searching for interindividual and interspecific differences in anti-parasite resistance. Although many examples of variability in health-related traits were described in natural animal populations, our knowledge about the underlying genetic features dermining this variance is only limited. It has been shown in numerous examples in laboratory animals, domestic animals and humans that variation in the Major histocompatibility complex (MHC) is unable to explain all known genetically determined immunological variation in animals. Still MHC is so far the only gene cluster studied in ecological immunology of free-living animals. In this review we therefore map the potential importance of another group of immunity genes, the Toll-like receptors (TLRs). These innate immunity receptors belong among the most essential components of animal pathogen-recognition system and being reasonably polymorphic they might be responsible for substantial part of variation in disease-resistance in animals.
Host-parasite relationships between the Daubenton's bat, Myotis daubentonii Kuhl, 1817 (Chiroptera: Vespertilionidae), and its haematophagous ectoparasite, the mite Spinturnix andegavinus Kolenati, 1857 (Acari: Spinturnicidae), were subjected to analyses based on data gathered during a six-year study (1999-2004) within a single study area in South Bohemia, Czech Republic. Seven hundred and fifty-one Daubenton's bats were examined by screening wing membranes with an intensive light source, resulting in 4,690 recorded mites. Sex, age, weight and reproductive state were evaluated for each bat. A body condition index was calculated as a ratio of weight to forearm length. The seasonal course of mite infestation displayed distinct dynamics with the peak during the lactation and post-lactation periods coinciding with occurrence of the most numerous colonies of Daubenton's bats in the study area. Infestation rates differed between the two sexes, being higher in adult females than adult males. Juvenile bats of both sexes (with no differences between males and females) were the most infested group of all. Pregnant females had a significantly higher parasite load than non-pregnant ones, while no differences in infestation rates were found between lactating and non-lactating females. The analyses of the relationship between parasite load and body condition of bats revealed no common trends for all sex- and age-related groups. Two possible explanations are suggested and discussed: (1) There is no true relationship between the two tested variables and, thus, the significant results were attained due to a random statistical effect. (2) Different underlying causal mechanisms may exist that influence parasite load and, especially, body condition, with respect to the particular sex and age category of bats. The seasonal roosting dynamics of the Daubenton's bat are suggested to be the result not only of changing energetic demands of resident population members, but also of coevolutionary strategies within host-parasite relationships.
About 300 species belonging to four superfamilies (Gnathostomatoidea, Habronematoidea, Physalopteroidea and Thelazioidea) of the nematode suborder Spirurina are known as the adult parasites of freshwater, brackish-water and marine fishes. They are placed in four families, of which the Gnathostomatidae, including Echinocephalus with a few species and the monotypic Metaleptus, are parasites of elasmobranchs, whereas Ancyracanthus contains one species in teleosts; the Physalopteridae is represented in fish by four genera, Bulbocephalus, Heliconema, Paraleptus and Proleptus, each with several species in both elasmobranchs and teleosts. The majority of fish spirurines belongs to the Rhabdochonidae, which includes 10 genera (Beaninema, Fellicola, Hepatinema, Heptochona, Johnstonmawsonia, Megachona, Pancreatonema, Prosungulonema, Rhabdochona and Vasorhabdochona) of species parasitizing mainly teleosts, rarely elasmobranchs, and the Cystidicolidae with about 23 genera (Ascarophis, Caballeronema, Capillospirura, Comephoronema, Crenatobronema, Cristitectus, Ctenascarophis, Cyclozone, Cystidicola, Cystidicoloides, Johnstonmawsonoides, Metabronema, Moravecnema, Neoascarophis, Parascarophis, Prospinitectus, Pseudascarophis, Pseudoproleptus, Salvelinema, Similascarophis, Spinitectoides, Spinitectus, Sterliadochona), with many species parasitic in teleosts only. Because of difficulties in studying fish spirurines, associated with their morphological and biological peculiarities, most species of these parasites are poorly known. It is apparent that their present classification system does not reflect phylogenetic relationships and a taxonomic revision of this nematode group, based on detailed morphological (including SEM and TEM), life history and molecular studies of individual species, is quite necessary. In Cystidicolidae, several genera have been based on details in the cephalic structures visible only with the aid of SEM, but it will be evident whether or not these tiny features are of generic importance only when more cystidicolids are described using SEM and comparative molecular data become available. Data on the biology of fish spirurines are scarce. In known cases, their life cycles involve aquatic arthropods (crustaceans or insects) as intermediate hosts, in which, sometimes, the larvae undergo a precocious development and may even attain adulthood and become gravid in these invertebrates; sometimes, fish paratenic hosts are known to occur in cystidicolids parasitizing as adults piscivorous definitive hosts. Some spirurine species are pathogenic and are known as causative agents of serious fish diseases. and Consequently, further detailed studies on fish spirurines are significant not only from the theoretical viewpoint, but they may also have practical implications.
The nematode superfamily Dracunculoidea includes 166 recognized species, of which 150 (90%) are parasitic in about 300 species of freshwater, brackish-water and marine fishes. Fish dracunculoids are placed in 31 genera (86% of all dracunculoid genera) belonging to eight of the nine dracunculoid families: Anguillicolidae, Daniconematidae, Guyanemidae, Lucionematidae, Micropleuridae, Philometridae, Skrjabillanidae, and Tetanonematidae; the genus Lockenloia is considered incertae sedis. Because of difficulties in studying fish dracunculoids, associated with their morphological and biological peculiarities, most species of these largely histozoic parasites are poorly known and males of the majority of species and of eight genera have not yet been discovered. It is apparent that the present classification system of dracunculoids as a whole does not reflect phylogenetic relationships and a taxonomic revision of this nematode group, based on detailed morphological (including SEM and TEM), life history and molecular studies of individual species, is quite necessary. Data on the biology of fish dracunculoids is scarce. In known cases, their life cycles involve copepods, ostracods or branchiurids as intermediate hosts and, sometimes, fish paratenic hosts are known to occur in dracunculoid species parasitizing as adults piscivorous definitive hosts. However, nothing is known about the life cycles of representatives of 20 genera. Some species of dracunculoids, particularly of philometrids, are highly pathogenic and are known as agents of serious fish diseases. During recent years, especially the importance of Philometra spp. parasitizing the gonads of many species of marine fishes has increased due in particular to the rapid development of marine aquaculture, because they may significantly decrease fish reproduction or even cause full parasitic castration. Therefore, further detailed studies on fish dracunculoids are significant not only from the theoretical viewpoint, but they may also have practical implications.
An examination of three specimens of the Morelet's crocodile, Crocodylus moreletii Duméril et Bibron, from the Lagoon of Celestún, Yucatan, Mexico revealed the presence of the following eight helminth species: Acanthostomum americanum (Pérez Vigueras, 1956), Pelaezia loossi (Pérez Vigueras, 1956), Telorchis sp. juv., Pseudoneodiplostomum groschafti sp. n. (all trematodes), Dujardinascaris helicina (Molin, 1860), Contracaecum sp. Type 2 larvae, Micropleura sp. and Paratrichosoma recurvum (Solger, 1877) (all nematodes). Pseudoneodiplostomum groschafti sp. n. is established by indication based on the description of specimens from Crocodylus rhombifer from Cuba, given by Groschaft and Baruš (1970). Acanthostomum acuti Caballero et Brennes, 1959 is considered a synonym of A. americanum. A. americanum and D. helicina are recorded for the first time from Mexico and Micropleura sp. is the first American representative of the genus recorded outside South America. Findings of A. americanum, Telorchis sp., P. groschafti, D. helicina and Micropleura sp. in C. moreletii represent new host records. Some observations on the early development of D. helicina are provided. All species, except for P. recurvum, are briefly described and illustrated and some problems concerning their morphology, taxonomy and geographical distribution are discussed.
The present paper comprises a systematic survey of nematodes found in 88 specimens of 24 species of freshwater fishes in Venezuela in 1992 and 1994. The following 13 species of nematodes were recorded: Adults: Guyanema longispiculum Moravec, Prouza et Royero, 1996, Guyunema sp., Procamallanus (Spiracamallanus) inupinatus Travassos, Artigas et Pereira, 1928, P. (S.) krameri (Petter, 1974) comb, n., P. (S.) pintoi (Kohn et Fernandes, 1988) comb, n., Procamallanus (Spiracamallanus) sp., Ruphidascaris (Sprentascaris) mahnerti (Petter et Cassone, 1984). Larvae: Anisakidae gen. sp., Brevimullicaecum sp., Ctmtracaecum sp. Type 1, Contracaecum sp. Type 2, Contracaecum sp. Type 3, Eustrongylides sp. All these parasites are reported from Venezuela for the first time and all findings represent new host records. Brevimulticae-cum larvae are reported from fishes for the first time. Almost all parasites are briefly described and illustrated and problems concerning their morphology, taxonomy, hosts and geographical distribution are discussed. A new name, Terranova diazungriai nom. nov. is proposed for T. caballeroi Diaz-Ungrfa, 1968 (a junior homonym of T. caballeroi Baruš et Coy Otero, 1966).