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Fifteen trematode species belonging to seven families parasitizing the females of Bithynia troscheli (Paasch, 1842) at metacercarial stage, were recorded in Kargat River (Lake Chany, South of West Siberia, Russia). The breeding mollusk females have less metacercarial diversity (9 species vs 15) and lower mean parasite abundance, comparing to non-ovigerous mollusks. The hypothesis of the metacercarial influence on individual fecundity of aquatic gastropods was tested. The individual fecundity parameters of the B. troscheli females, uninfected and infected with the trematode metacercariae belonging to fam. Echinostomatidae, Cyathocotilidae, Strigeidae, Cyclocoelidae, were compared. The percentage of the breeding B. troscheli females was less and their fecundity parameters were lower for the hosts infected (with the Strigeidae or Cyclocoelidae metacercariae) comparing to non-infected ones. Trematode metacercariae found in the mantle or somatic musculature had no significant effects on the fecundity of the host. However, our results showed that trematode metacercariae affect the reproduction of B. troscheli in dual ways. All fecundity parameters of the mollusk females with the high infection rate were significantly lower than those for uninfected females: the percentage of fecund females (χ2= 6.73, p < 0.01), number of clutches per female, number of egg capsules per clutch and number of normal egg capsules per female (Tukey HSD, p < 0.001). Although the females with low intensity of metacercarial infection lay egg clutches significantly more frequently than uninfected ones (χ2 = 4.18, P = 0.04); the fecundity parameters were approximately equal for both groups of the mollusk females. These pioneer results prove the reality of influence of metacercariae on the individual fecundity of aquatic gastropods. The regulatory population mechanisms that may compensate the host reproduction loss caused by metacercaria, are discussed.

The Ixodes persulcatus life cycle has been studied in natural environments of taiga forests in The Eastern Sayan Plateau (56°10' N, 91°30' E). Engorged larvae and nymphs develop with a morphogenetic diapause or without diapause, with ratio of these two ways of development for larvae and nymphs 77.25/22.75 % and 43.43/56.57 %, respectively. The hypothetic season hemipopulation consists of 34.5 ± 4.5, 50.1 ± 1.3, 13.2 ± 4.0 и 2.2 % of unfed imagoes, completing 3-year, 4-year, 5-year, and 6-year life cycles, respectively. Mean life span is 3.83 ± 0.10 years per generation. The "life table" predicting the probability to complete life cycle through phases from egg to adult, was developed.

Microtine rodents were captured in two disconnected sampling sites in Omsk region where Ixodes persidcatus and Ixodes trianguliceps are sympatric. In blood samples of rodents the DNA was revealed belonging to several ixodid-transmitted pathogens: Borrelia burgdorferi sensu lato (prevalence 20.0 and 6.0%, here and further values are given for the first and second site, respectively), Borrelia miyamotoi (8.3 and 2.0%), Anaplasma phagocytophilum (33.3 and 48.0%), Ehrlichia muris (30.0 and 2.0 %) and Babesia microti (33.3 and 42.0 %). Three genetic groups of A. phagocytophilum based on 16S rRNA gene and groESL operon, as well as two genetic groups of B. microti, B. microti 'US'-type and B. microti 'Munich'-type, were detected.

During January—May, 2007, 105 specimens of minnow of the 2+—3+ age were collected from the Pechora River in the central homestead of the Pechora-Ilechsky Natural Reserve, and studied using the standard technique of the general parasitological dissection. It was concluded that in a period of studies the component parasite community was in a formation process.

Immunolabeling method of microsporidium Paranosema locustae proteins on cryosections of locust infected fat body was proposed. In contrast to single parasite cells and artificially infected host cell cultures, this method allows to study molecular mechanisms of host-parasite relationships and in particular the secretory microsporidial proteins either at cellular or tissue level. Immunolocalization of the EPR-specific and cytoplasmic forms of Hsp70 family of molecular chaperones on cryosections showed accumulation of these proteins in the respective compartments of intracellular developmental stages of P. locustae and their absence in host structures. This allows to use them in diagnostics of microsporidiosis lesions in infected tissues as well as in colocalization analysis with P. locustae secretory proteins as a marker of parasite. The cytoplasmic chaperone stains cytoplasmic compartment homogeneously, but in the infected host cell during sporogony it disappears partially from the intracellular stages of development which damaged by maturing spores. Thereby study of molecular mechanisms of host-parasite relationships is to be carried out at the earlier stages of infection before active sporogony.

The structure of the information system "Biodiversity of dipteran insects of the „gnus" complex of the northeastern European Russia" is described. Perspectives of its use in regional parasitological studies and for the public information on bloodsucking insects control are discussed.

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