A new parasitological index for the estimation of peculiarities of the relationships between parasite and its host, and biotope of the host. P. 105-112.
A new parasitological index (hostal-topical index) for the estimation of the degree of ectoparasite's relationship with its host and biotope of the host is proposed: ИГТ = n/N — n1/N1 x n2/N2 , where ИГТ — hostal-topical index; n — amount of ectoparasites of the given species on the given host species in the biotope; N — amount of ectoparasites of all species from the given taxonomic group on the given host species in the biotope; n1 — amount of hosts of the given species in the biotope; N1 — amount of hosts of all species from the given taxonomic group in the biotope; n2 — amount of ectoparasites of the given species in the biotope; N2 — amount of ectoparasites of ail species from the given taxonomic group in the biotope. Values ИГТ < 0.1 indicate that there is a distinct relationship with the biotope in spite of the host; values fallen into the range 0.1 < ИГТ < 0.5 indicate a moderate relationship with the biotope through the host; values ИГТ > 0.5 indicate a significant relationship with the host. By means of this index we have analyzed peculiarity of several parasitic species of fleas and gamasid mites to their hosts, biotopes, and biotope through the host. As it was found on the materials from different native zones and subzones of the Omsk Region (Western Siberia, Russia), values of the hostal-topical index for polyhostal parasitic species are lesser than those for oligohostal species. Values of this index can be different for the same species in the different native zones and subzones as well as in the different biotopes of the same native zone (subzone).
Modern problems in the study of tick-born encephalitis natural foci. P. 113-123.
A new conception of natural focus as anthropo-parasitic system is given by an example of tick-born encephalitis. Problems of natural foci classification and zoning of focal territories, as well as patterns of ecological relations in these systems, are considered. Causes and factors affected expansion of the infection are analyses.
Tarsal sensory complex of the red chicken mite Dermanyssus gallinae (Acari: Dermanyssidae). P. 124-131.
The tarsal sensory complex of the red chicken mite Dermanyssus gallinae is situated on dorsal surface of each fore leg near the claw. It comprises 28 sensilla of 5 morphological types: 4 SW-UP (single-wall upper-pore) (gustatory organs), 8 SW-WP (single-wall wall-pore) (olfactory organs), 8 DW-WP (double-wall wall-pore) of two subtypes (thermo-chemoreceptory organs), 6 NP-TB (no pore — tubular body) (tactile organs), and 2 reduced sensilla. No sex or stage dimorphism was revealed. Morphological data point to the fact that tarsal sensory complex of the red chicken mite is mainly an organ detecting temperature changes and olfactory stimula.
Chronological and physiological age of the tick Ixodes ricinus females. P. 132-139.
Changes of the physiological age in 3 groups of the laboratory reared Ixodes ricinus females were investigated over the period of 6—16 months. The longevity was studied in 27 groups of the tick females from a wild population during 2 seasons of the tick activity. Physiological age of the tick females was determined at the beginning of the study and then monthly till the end of the study. It was established that physiological ageing takes place during the life of the tick, and the ageing of different females is carried out non-uniformly. Physiologically young females (of the second physiological age) in the groups of laboratory reared ticks were occurred right up to 11th month after molting (including 4 months of hibernation in a refrigerator). Ticks of the second physiological age were occurred in the groups from wild populations after one or two periods of hibernation. Hence, in natural conditions some females may be physiologically young both in the first and second seasons of the ticks' activity. On the other hand, physiologically old tick females (of the 4th physiological age) appeared in the groups in a month after molting. The supposition is proposed that the tick population is heterogeneous by the rate of the individual ageing. It means that different specimens differ by the rate of consumption of their storage compounds i. e. by the intensity of metabolism. Such difference may be a cause of the variability in chemical conditions in the gut of the tick being the habitat of Borrelia.
Lernaea cyprinacea (Copepoda, Lernaeidae) from crucian carp Carassius carassius from the Dlinnoje Lake in the middle stream of the Vychegda River. P. 140-154.
Till 1996 the Vychegda River's flood lakes at the territory of the biological station of the Syktyvkar University were overflowed every spring by water so that fishing took place from time to time. In 1996 a low flood level and intensive fishing resulted in the change of the infection rate of crucians by Lernaea, as well as in the change of the size and sex ratios of the crucian population in the Dlinnoje Lake. Thus, the size pattern of the crucian population became simpler, and it led to the changes in parasite-host relation. As a result, the intensity of the invasion of crucians by Lernaea cyprinacea have increased and the distribution of the parasite in the host population does not fit by the negative-binomial distribution. Crucian females and males play an equal role in the maintenance of the parasite population. In 1984 crucian females of medium and large body length played the main role in that process. Functions of other host groups (fishes of small body length, males) were different. Up to 2001 a significance of "k"-exponent of the negative-binomial distribution, describing the number of copepods in the mature part of crucian population, changed with a small range that suggests a stability of parasite-host relationship in the investigated crucian groups. We suppose that after a period of an unstable state in 1997—2000 the population of the parasite reached a new stable state.
Analysis of parasitic communities in fishes from Lake Baikal. P. 155-170.
Analysis of infracommunities and component communities of fish parasites in Lake Baikal has been conducted for the first time. It has been revealed that parasite infracommunities for the majority of Baikal fishes are weakly balanced and impoverished (the Berger—Parker Index is > 0.5; Evension is < 0.5; the Brillouin Index is < 1). The highest diversity and balance of the communities are characteristic for carnivorous fishes (Brachymystax lenok, Hucho taimen, Thymallus arcticus, Esox lucius, and Perca fluviatilis). The component parasitic communities of Leuciscus leuciscus baicalensis, Rutilus rutilus, and Leocottus kesslerii are the most diverse in Lake Baikal since the Shennon index for L. leuciscus baicalensis, R. rutilus, and L. kesslerii is 2.4, for Paracottus knerii — 2.2, Limnocottus godlewskii — 2.3, Phoxinus phoxinus — 2.1, Lota lota and Limnocottus pallidus — 1.9, P. fluviatilis — 1.8, Leuciscus idus — 1.8. The component parasitic communities of other fishes in Lake Baikal have low indices of biological diversity (H = 0.5—1.05, Smp is close to 1). A classification of mature and immature components of parasitic communities based on the ratio of specialist species and generalist species has been proposed. It is established that the component parasitic communities in sublitoral, profundal, and pseudoabyssal zones are mature, while in the littoral zone they are immature (impoverished and weakly balanced). The component parasitic communities in benthophagous fishes and predators are mature, in planktivorous fishes they are immature. The component parasitic communities are mature in the family Cyprinidae and immature in the families Coregonidae and Cottidae. The component parasitic communities of the Boreal Plain and Boreal Submountain faunal complexes are mature, but they are immature in Lake Baikal and Arctic freshwater complexes.
Parasite fauna of the perch fishes Percidae in waterbodies of the Kola Region. P. 171-184.
Results of the parasitological investigation of two species of perch fisches (perch Perca fluviatilis and ruff Gymnocephalus cernuus) from Kola Region are given. 63 species of parasites were found on perch in 16 waterbodies belonging to the White Sea and Barents Sea basins (Myxosporea — 3, Pleurostomata — 1, Suctoria — 2, Peritricha — 21, Protozoa incertae sedis — 1, Monogenea — 2, Cestoda — 6, Trematoda — 10, Nemadota — 8, Acanthocephala — 4, Hirudinea — 1, Bivalvia — 1, Crustacea — 3). 33 species of parasites were found on ruff in 5 waterbodies belonging to the White Sea basin (Cyrtostomata — 1, Hymenostomata — 1, Peritricha — 8, Monogenea — 2, Cestoda — 6, Trematoda — 9, Nematoda — 2, Acanthocephala — 2, Bivalvia — 1, Crustacea — 1). Data on the infestation of perch and ruff by different parasite species are obtained, occurrence of the parasites in the examined waterbodies is shown.
Seasonal dynamics of the population structure of Sphaerostomum globiporum (Trematoda: Opecoelidae) maritae in Ladoga Lake. P. 185-191.
Data on the seasonal dynamics of population structure is obtained for the first time for the Trematode species Sphaerostomum globiporum from roach Rutilus rutilus (L) in Ladoga Lake, which situates in the northern limit of the distribution range of this species. The parasites infest the host in October and leave it from the end of July to the beginning of August. The maximum of the magnitude of the Trematode population falls on spring, and the minimum is observed in summer. In August and September roach is free of the parasites. It is established that the period of maturing occupies 10 months for S. globiporum from roach in Ladoga Lake. The prereproductive period takes 5 months and comes to the end in February. The reproductive period occupies 5 months too. Although these two periods of the parasite's life cycle do not separated from each other clearly, an overlapping of two generations was not observed, unlike the case of more southern water bodies.
The use of endobiotic ciliates from old collections in transmission electron microscopic investigations. P. 192-200.
The opportunity of the use of formalin-fixed endobiotic ciliates from old collections in transmission electron microscopic investigations (ТЕМ) has been studied. Ciliates from the following species were examined: Ditoxum funinucleum Gassovsky, 1919 from the hindgut of Equus hemionus kulan Groves et Mazak, 1967 preserved in a collection during 19 years, Blepharoprosthium pireum Bundle, 1895 and Cochliatoxum periachtum Gassovsky, 1919 from the hindgut of the Yakut horse Equus caballus L. stored during 1.5 years, and Triplumaria heterofasciculata Timoshenko et Imai, 1995 from faeces of the Asian elephant Elephas maximus L. stored during 2.5 years. It is shown, that the main taxonomically important characters of the cortex ultrastructure, ciliature, and internal fibril structure of the cell of Trichostomatia keep well during a long-term storage in formalin.