Ecological, morphological, and molecular studies of Acanthocheilonema odendhali (Nematoda: Filarioidea) in northern fur seals (Callorhinus ursinus) on St. Paul Island, Alaska.

Studies of northern fur seal (Callorhinus ursinus Linnaeus, 1758) infection by the filariid nematode Acanthocheilonema odendhali were carried out in 2011-2012 on St. Paul Island, Pribilof Archipelago, Alaska. Skins of 502 humanely harvested northern fur seals from haul-out areas of five rookeries, Polovina (n = 122), Morjovi (n = 54), Zapadni (n = 72), Lukanin (n = 109), and Gorbatch (n = 145), were examined. A. odendhali was found in 18% of northern fur seals. The prevalence of infection ranged from 12.5% up to 22.9% on different haul-out areas on the island. The mean intensity of infection was 1.3 (range 1-7). Detailed morphological examination of collected specimens was performed using light microscopy. Several characters were added to the morphological description of the species, among them lateral thickening of the body cuticle, especially prominent in males, variations in number and position of genital papillae in males, transverse striation of the cuticle, and terminal dilation on tail end in microfilariae. The adult specimens studied had a shorter esophagus than type specimens from the California sea lion described by Perry (1967). Comparison of partial sequences of the mitochondrial cox1 gene from specimens collected from five sampling sites on St. Paul Island and a specimen from the type host and territory in California showed no significant differences and strongly supported conspecificity of the material from Alaska with A. odendhali.

Field study on the survival, migration and overwintering of infective larvae of horse strongyles on pasture in central Ukraine.

Experimental studies on the survival of infective stage larvae of horse strongyles and their ability to overwinter on pasture were carried out in central Ukraine (Poltavska oblast). Faecal pats (1.5 kg each) of naturally infected horses were placed on pasture, and samples of faeces and surrounding vegetation (10 g each) were collected each month, excluding the winter months, from November 2002 until April 2004. The number of infective third stage larvae was calculated in each sample and compared with that from the control faecal samples cultivated in the laboratory. In the control samples, the ratio of infective third stage larvae to the initial number of eggs was from 54.7% in June up to 84.2% in November. This ratio depended on the presence of nematophagous fungi growing in the faeces. On pasture, the development of larvae to the infective third stage took approximately 4 weeks in the warm season, from April until September. In October, a percentage of the eggs (25% to EPG value) did not hatch. No larval development was observed in faeces in November. A minute quantity of larvae, about 0.03% of their initial number, was observed to survive on pasture for the 12 months. Migration of infective larvae from the faeces to vegetation was not intensive, between 71% and 89% of larvae remained in the faeces 4 weeks after deposition of the faecal pats, the percentage related to soil humidity in each month. The proportion of larvae successfully surviving during winter appeared to be maximal in faecal pats deposited on pasture in September of the previous year (up to 42.0% of the initial number of larvae). Some larvae were observed surviving winter in soil beneath the faecal pats. The results of the study demonstrated that horse pastures in the central part of Ukraine are never free from the infective third stage larvae of strongyles.

Helminths of the sand lizard, Lacerta agilis (Reptilia, Lacertidae), in the Palaearctic: faunal diversity and spatial patterns of variation in the composition and structure of component communities.

We studied variation in the structure of component communities of helminths in sand lizards, Lacerta agilis, from 30 localities in the Ukraine and Bulgaria. Thirty-five separate samples of lizards, with a total of 661 completely censused infracommunities, yielded 30 helminth species (4 cestodes, 10 trematodes, 3 acanthocephalans and 13 nematodes). In its range within the Ukraine, L. agilis serves as the final host for 13 species of which only 3 (S. lacertae, S. hoffmanni and P. molini) can be considered as lizard specialists. A characteristic feature of these helminth component communities was the large proportion of heteroxeneous helminth species for which L. agilis serves as paratenic host. Sand lizards in the meadow steppeland zone were primarily parasitized by larval helminths that represented a major proportion of the total number of all worms recovered while those sampled in the grassland/forest transition zone were characterized by substantially higher proportions of adult helminths using lizards as final hosts. However, L. agilis was parasitized by a much higher proportion of lizard specialists in the 'typical' habitats of the meadow steppeland zone as opposed to those located in 'marginal' habitats in the grassland/forest transition zone, where helminths were shared to a greater extent with amphibian hosts.