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The purpose of this communication is to provide a combined, morphophysiological and ecological analysis of ontogenesis in Parasitengona mites that is characterized by the phenomenon of "alternating calyptostasy" (Kethley, 1991). The enrichment of eggs in yolk and the progressive embryonization of prelarvae represent the evolutionary tendency of accelerated development, that theoretically could lead to a complete loss of capability to feed at the larval phase. Indeed, the trombiculid mite larvae (Trombiculidae) undergo the post-moult development and completely utilize the masses of embryonic yolk in the giant mid-gut cells. Theoretically, this situation may lead to the quite moderate feeding of larvae that may be seen in some other groups of the Acariformes. Nevertheless, it does not take place because it is necessary for larvae to reach, during their feeding, the large sizes of deutonymphs and adult mites, which reproduce a conservative morphological prototype with apparent secondary simplification. This is a result of the finest preadaptation of these mites to the animal carnivorous diet and of the following specialization of the active post-larval instars to the egg-feeding on insect preys. The extra-oral digestion and the favourable specialization have provoked the hypertrophy and closing of the mid gut and the final stabilization of the conservative morphology. Thus, the differences between the early and the late stages of mite development in their sizes and the feeding specialization of postlarval stages lead to the following ontogenetic steps in recent parasitengona groups. The prelarva is a specialized instar for the utilization of the embryonic yolk with fixed ontogenetic status. The larva is the first active instar which feeds superfluously and reaches, during its effective parasitic feeding, the approximate sizes of postlarval stages due to the ingestion of large masses of the liquid food. It has an inevitable result of the non-feeding and the gradual regression of the protonymph instar. The tritonymph instar reduces synchronously with protonymph that obviously indicate the concordant evolution of the whole ontogenesis as a separate evolutive unit. The latter takes place entirely within the soil and litter, the environment with a quite low degree of the different evolutive trends. The free-living deutonymphs and adult mites remain as active instars and are reserved in ontogenesis for feeding and reproducing small eggs riched in yolk. These complex factors are supposedly interknitted in the real course of the "accelerated development" (Kethley, 1991).

The distribution range of Ixodes pavlovskyi has the Pliocene disjuntion into two main areas (fig. 1). The western area includes mountains of southern Siberia (Salair ridge, Kuznetskyi Alatau, Western Sayan, Altai, Dzungarian Alatau, and Tarbagatai). The eastern area is situated in western macroslope of Sikhote Alin ridge. Seventy-five females, 75 males, 63 nymphs, and 69 larvae have been studied in three close locations of eastern slope of Salair ridge — western one of Kuznetskyi Alatau (Д), in s.-w. Altai (В), and in four close locations of w. Sikhote Alin (C). Forty specimens of all stages in seven other locations have been studied also. All corresponding morphometric characters are overlapped in the range of I. pavlovskyi, but 15 measured characters and 5 proportions of organs have statistically significant differences (in accordance with Student's test, p = 0.05) in each main disjunct areas, i. e. in western area (A, B) on the one hand and eastern area (C) on the other hand (tables 1—12). In these areas four characters (length of II—III palpal atricles, length of medial spur of coxa I, length of tarsus I, and proportions of tarsus I) have significant differences in larva, nymph, female and male simultaneously (transit characters). Two more characters (length of gnathosoma and hypostome) have significant differences in male, nymph, and larva in western and eastern areas. It is essential that sizes of corresponding organs of all stages of ontogenesis have the same tendency: in the western area (A, B) — smaller, in eastern one (C) — larger. Many characters differ significantly in one — two stages or sexes. As a whole there are significant differences between the western and eastern samples by 29 measured characters of 57 ones studied (table 13). In addition nearly 70% of females in disjunct areas have differences of shape of fissures of scutum, hypostome, tarsus I (fig. 2), and of colour of legs. The great number of statistically significant differences in all stages permits choosing two subspecies: eastern — I. pavlovskyi pavlovskyi Pomerantzev, 1946 and western one — I. pavlovskyi occidentalis Filippova et Panova, ssp. nov. The differential characters may be all those, having significant differences in sizes or proportions, especially transit characters (tables 1 and 2, heavy type for A—С toghether), and shape of some organs in female (fig. 2). The number of significant differences between samples in locations A and В within the western area (fig. 1, tables 1, 2, the asterisks) is less than between subspecies. There are no transit differences between A and B. The morphological differentiation of subspecies corresponds to age and distance of disjunction of the range of species I. pavlovskyi.

An increase of the number of Borrelia burgdorferi s. l. in nymphs was observed 3—4 months later the moulting and during the following 4—5 months. The percent of infected ticks remained unchanged. The reproduction of spirochete was going not only at a room temperature, but also at a lower temperature, 3—5° (imitation of hibernation conditios). An increase of the spirochete density was especially well marked, when the ticks were maintained under fluctuated daily conditions. We have foud out the difference in the transphase transmission. Almost all larvae and nymphs infected by a bloodsucking retained spirochetes after moulting (the first transphase transmission). When the nymphs infected at larval stage were fed bn an uninfected mouse, only 30% of imago ticks retained the spirochetes (the second transphase transmission).

Mammals and ticks was collected in 1995—1997 years in Novgorod region from May to September. Traps were exposed during 5 consecutive days every month in 4 different biotops. 928 hosts were captured during three years. 357 larvae and 59 nymphs of Ixodes persulcatus, 356 larvae and 71 nymphs of I. trianguliceps were collected. The Clethrionomys glareolus and Sorex araneus are main hosts of larvae of I. persulcatus and I. trianguliceps. C. glareolus feed 76.2% of I. persulcatus larvae and 25% of I. trianguliceps larvae, S. araneus — 27.1 and 45.9% of larvae, respectively. The abundance of larvae and nymphs of I. persulcatus was 0.26 and 0.13 on C. glareolus, and 0.41, 0.08 on S. araneus; for I. trianguliceps this indices are 0.15 and 0.09, 0.95 and 0.13, respectively. Infection rate of larvae and nymphs I. persulcatus and I. trianguliceps with Borrelia burgdorferi s. l. was 94—100%, confirmed by IFA with H5332. The borreliemia was found in 13.6% C. glareolus, 6.6% — Microtus arvialis, 4.2% Apodemus uralensis. For all species of sorex this index varied from 0.9 to 44.9% in different years. Increase of mammal's numbers with the borreliemia correlated with peaks of activity of larvae of I. persulcatus. Finding of Borrelia burgdorferi s. l. in I. trianguliceps indicates an occurrence of enzootic locuses.

Infection rate of 11 parasite species was investigated in the Theragra chalcogramma of 6 year age during the pre-sprawning period in western part of Bering Sea and in a pacific aquatory of Kamchatka. It was found, out that adults of T. chalcogramma near Comandor Islands are represented by a mixture of comandor group fishes and ones migrated from Bering Sea. The main characteristic of the comandor group is the presence of a proboscis worm Corynosoma sp. and absence of cestode larvae P. phocarum and G. erinaceus.

The paper contains data on 20 trematode and 36 cestode type materials, which entered into the Museum of Institute of Parasitology RAS during ten passed years.

Activities and properties of NADF-dependent isocitrate dehydrogenases in cytosol and mitochondrial fractions from trematodes Eurytrema pancreaticum and Calicophoron ijimai were examined. Cytosol and mitochondrial enzymes were activated by ions Mn2+ and Mg2+ and inhibited by ions of heavy metals and p-chloromercuribenzoate. The effect of anthelmintic preparations on activity of enzymes was investigated.

Peculiarities of pathogenesis of Gryllus bimaculatus fat body infected with Adelina grylli were investigated by means of histochemical methods and electron microscopy. The obtained results revealed the following. 1. Abrupt disappearance of glycogen from parasitized host cells, which takes place already at early stages of infection and is accompanied by accumulation of glycogen by parasites. 2. Gradual disappearance of fat drops from cytoplasm of infected cells, complete disappearance of fat drops being observed only if the tissue is filled with cyst stages and its integrity is actually distroyed. 3. The pathogenesis of insect coccidiose is closely connected with extraordinary hemocyte reaction of the host, apparently induced by parasites. Such a reaction results in the infiltration of the fat body with hemocytes and formation of melanized capsules around oocytes. In fact the activation of the hemocyte reaction is the transition from intracellular parasitism to the tissue one.

Activities of hexokinase (EC 2.7.1.1), glycerol-3-phosphate dehydrogenase (EC 1.1.1.8), pyruvate kinase (EC 2.7.1.40) and alcohol dehydrogenase (EC 1.1.1.1) were measured in fat bodies of control, infected with Nosema grylli (Microsporidia) (M) and infected with Adelina grylli (Coccidia) (C) crickets Gryllus bimaculatus. Measuring did not show alterations of the hexokinase activities in fat body of crickets with both infections in comparison with the control. Two parasites caused an increase of glycerol-3-phosphate dehydrogenase activity (in 6 times with M and in 4 times with C). Pyruvate kinase activities increased approximately in 10 times in fat body with M infection, but С did not cause alterations of activity of this enzyme. In contrast, the alcohol dehydrogenase activity increased in 2—3 times in fat body with С infection, but did not alter in the case of M infection. Data about influence of M and С on enzymes activities are discussed.

The paper gives brief biographic data biologists, to whom the valid names of mosquitos, described from the former USSR, had been dedicated.

The oocyst are oval, 13.5—19 by 11 —16.2 µm. The oocyst's wall is smooth, colorless and consisted of a layer with two outlines, without a micropyle. The sporulation time is three days. The sporocyst are ovoid, 10.8—13.5 by 5.4—6.7 µm. The sporocyst residuum and Stieda body are present.