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Karyotypes of four species of blackflies belonging to plesiomorphic superspecific taxa, Prosimulium pronevitshae, P. frontatum, Stegopterna richteri, Greniera dogieli have been studied. Structural peculiarities of polythene chromosomes of the salivary glands in older larvae have been analysed. Banding patterns of polythene chromosomes and descriptions of these karyotypes are given for the first time. Karyotypical features of the examined species are compared. Based on the comparative karyological analysis the differences between taxa and their possible relationships are revealed.

Ixodes trianguliceps is a common tick species of the Eurasian forest zone. These ticks live probably in natural foci of ixodid tick-borne borrelioses (ITBB) from Western Europe to Transbaikalia, but their role in circulation of corresponding pathogens remains unclear. This study was performed in a natural ITBB focus iocated in the Perm region of Russia (near the Urals), where Borrelia garinii and B. afzelii circulate and I. persulcatus serves as their main vector. In July-August of 1994, 296 small mammals (mostly Clethrionomys glareolus) were tested for tick infestation. From these mammals, 49 I. trianguliceps and 252 I. persulcatus ticks were collected (16.3 and 83.7%, respectively). I. trianguliceps ticks were found on 33 rodents of three species: Cl. glareolus, Cl. rutilus, and Microtus oeconomus. The abundance of I. trianguliceps (on average, less than 0.2 ticks per animal) was approximately five times lower than that of I. persulcatus. I. trianguliceps larvae, nymphs, and adults (22, 15, and 5 specimens, respectively) were analyzed for Borrelia infection by plating their intemal organs on the BSK-2 medium. Spirochete isolates were obtained from four nymphs. Three infected nymphs were collected from different Cl. glareolus specimens, and one was found on Cl. rutilus. According to the results of RFLP analysis, all four isolates were classified as B. garinii. This experiment is the first successful attempt to isolate on of ITBB pathogens from I. trianguliceps ticks. These ticks do not attack people, and their roie in ITBB foci should be analyzed only in terms of epizootiology. The results of previous zoological-parasitological and bacteriological studies performed in the Ural region suggest that I. trianguliceps and I. persulcatus populations are maintained there by the same species of small rodents and insectivores, which mostly belong to the genera Clethrionomys and Sorex. Many of them were identified as the reservoir hosts of Borrelia. These data, in complex with the fact of B. garinii isolation from I. trianguliceps, suggest that I. trianguliceps ticks are involved in the maintenance of Borrelia circulation in natural ITBB foci. Taking into account the low abundance of these ticks in the Ural forests, they should be regarded as an important but not principal component of the epizootic process. It is suggested that such a conclusion about the significance of I. trianguliceps ticks also pertains to ITBB foci of other regions.

There were 22 species of fleas recorded on different Rodentia and Insectivora in the Kostroma region. The flea species M. turbidus, M. penicilliger, M. walkeri, C. agyrtes, C. uncinatus, P. sylvatica dominate on the rodents, and the species C. bisoctodentatus, P. soricis, P. kohauti, D. dasycnema dominate on the insectivores.

There are 27 ectoparasites species recorded now on the root voles Microtus oeconomus in Byelorussia. Among them, 14 species are recorded for the first time in the territory of the republic.

The daily emission dynamics of the intertidal cercariae P. atomon was studied in situ. P. atomon larvae have a circadian emission rhythm with an evening maximum. The temperature affects the process positively and the light does it negatively. The emission rythm of the cercariae corresponds to the biology of their second intermediate host, intertidal gammarides.

Three species of genus Bacciger from the fishes of Black and Mediterranean Seas are described. It is shown, that B. bacciger (Rud., 1802) is specific to atherinids, B. israelensis Fischthal, 1980 to sparids, B. minutus Gaevskaja et Naydenova n. sp. to engraulids.

The study of the effect of plerocercoid Ligula intestinalis infection on activity of digestive enzymes and glycogen content in bream tissues has shown, that the invasion decreases the activity of intestinal cavity enzymes and properly intestinal enzymes. The general proteolitic activity is decreased more than the general amilolitic activity. The kinetic characteristics of the properly intestinal enzyme are changed. The glycogen contents in muscles and hepatopancreas are decreased, and its ratio in these tissues is changed.

The pikeperch, the aborigen of the White lake, was introduced into the Kubenskoye lake in 1934-1936, where it has survived and become the object of intensive fishing. 1550 specimens of the pikeperch were removed from the Kubenskoye lake to the Vozhe lake in 1987. In the Kubenskoye lake the parasite fauna of the pikeperch has been enriched with 18 parasite species. The pikeperchs in the Vozhe lake have revealed 5 parasite species. Some typical regularities have been observed in the changes of the parasite fauna of the introduced fishes in a new lake: at first the pikeperchs get rid of parasites, then an enrichment of the pikeperch parasite fauna begins. It is caused by the changes in the pikeperch ecology.

The ultrastructure of Stempellia diaptomi Voronin, 1977, a parasite of the Diaptomus gracilis Sars (Crustacea, Calanoida) is described with emphasis on its systematic position. Nuclei are unpaired at all stages of the life cycle. Ribbon-like meronts lie in direct contact with the host cell cytoplfism, have 4-6 of nuclei and divide by binary fission or plasmotomy. The sporogonial plasmodium divide by a rosette-like budding, producing 6-16 sporoblasts. The sporophorous vesicle wall is fine, membrane-like and fragile. Vesicles with sporoblasts have small and polymorphic electron-dense inclusions. Fresh spores are elonga-te-ovoid or pyriform, measure 3.7 ± 0.2 X 1.9 ± 0.2 um. The polaroplast has two lamellar parts, where the anterior lamellae are the widest. The heterofilar (or slightly anisofilar) polar filament is arranged in 7-8 coils which are subdivided as (1-2) + 1 + (5-6). The exospore is layered. On the basis of the ultrastructural cytology the microsporidium is transferred from genus Stempellia to the genus Flabelliforma.

A description of a new species of homoxenous adeleid coccidia is given. Host - imago and nymphs of Gryllus bimaculatus Deg. Localization - fat body. Point of discovery - laboratory culture of crickets from natural populations of surrounding of Ashkhabat (Turkmenistan). Diagnosis (all dimentions are given in micrometres, in straight brackets are given dimentions of fresh material). Sporozoite - vermiform, 25 X 5.5, nucleus 3.4 X 2. Meront - 25.6 X 16.4, given rise to 20-40, usually about 40 merozoites packed either perpendicular or parallei to each other or laying spirally; residual body has not been found. Merozoite - vermiform, 22.6 X 2.4, nucleus 4.35 X 2. Female schizont - 23.9 X 19.8, gives rise to 9-21, usually 12-16 female zoites (macrogamonts) packed parallelly to each other with residual body. Male schizont -24.4 X 14.4, gives rise to 5-16, usually 8-10 male zoites, packed parallelly to each other in two poles of one and the same schizont. Female zoite - vermiform, 20.9 X 4 [22.1 X 3.6], nucleus 4.4 X 2.1. Male zoite -oviform, 11.4 X 4.6 [16.9 x 4.6], nucleus 4.1. Syzygy: - macrogamont 24.5 X 18.8 [20.5 X 17.1], microgamont 7.5 X 5.5 [9.6 X 7.45]. Microgamete - 3.5 X 2.45. Oocyst - 36.3 X 30.1 [32.5 X 24.7], the number of sporocysts in the oocysts - 4-22, usually 6-10. Sporocyst - diametre 9.9 [13.3], dizoic. A differential diagnosis is also given. The new species is named Adelina grylli due to the host's generic name.

Fat body of Gryllus bimaculatus is beeing infected with two intracellular parasites Nosema grylli (Microsporidia) (M) and Adelina sp. (Coccidia) (C). It is known that M penetrate inside host cells through the polar filament, develop without a parasitophorous vacuole (at least Nosema-species), do not possess mitochondria and any visualized nutrients. C invade host cells by induced endocytosis, develop inside a vacuole, possess mitochondria and store nutrients in special granules. We noticed that infection with M (in contrast to C) suppressed the development of the female reproductive system of crickets. We suppose that all mentioned pecularities should evolve a specific influence of M and C on the metabolic proces-es of hosts, especially in such crucial and energy-consuming period of their life as an ovary maturation. Measuring showed that infection with M caused prominent reducing of gonad weight in virgin females and a simultaneous hypertrophy of their fat bodies. None of these effects was caused by C. Specific activities of 3 dehydrogenases: (1) cytoplasmic forms of NAD-dependant malatdehydrogenase (EC 1.1.1.37) (MDH), (2) malic-enzyme (EC 1.1.1.40) (ME) and (3) glucose-6-phosphate dehydrogenase (EC 1.1.1.49) (G-6-PDH) were measured spectrophotometrically in cricket fat bodies infected with two parasites. M caused a decrease of activities of studied enzymes in fat bodies of 2-23 day felames: activity of MDH reduced in 1.5 times; ME - in 2.6; G-6-PDH - in 1.3-1.4, comparatively with the control. Infection with C leaded to a slight decrease of MDH activities and didn't cause statistically significant alterations in activities of ME and G-6-PDH. We suppose that lowering of enzyme activities is connected with suppressing of gonad development by M.

Peculiarities of the pulmonary and skin respiration of Lymnaea stagnalis in cases of 10-days starvation, infection with parthenites Echinostoma miyagawai, and repeated poisoning with the solution of nitric acetic lead (concentrations 15, 50, 85 mg/1). The degree of changes in such indices as the time of inspiration and length of interval between inspirations depends upon the intensivity of trematode infection and concentrations of the toxin.

A new species of blackflies, Montisimulium peskovi sp. n. from the northern Tien-Shan (Kazakhstan Republik) is described. Morphological characters of development phases are given. The photomaps of the salivary polythene chromosomes are constructed.

It was found out, that non-lineal young white rats have a natural resistence to the leishmania infection, but it coud be overcome with the mean of immunosupression caused by the corticosteroid of prolonged action Tricort-40. The leishmania infection caused by immunosupression is successfully eliminated by the animal organism soon after the stopping of immunosupressant action, that coud be considered as the restitution of the natural resistence.

Morphological peculiarities of some adaptation characters of the spores Henneguya cutanea Dogiel et Petruschewsky, 1933 (Myxosporidia) is considered.

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