[Studies of the biological age in adult taiga ticks Ixodes persulcatus (Ixodinae)].

The history of studies of the biological age in ixodid ticks is discussed. A method of estimation of the biological age in adult ticks of the genus Ixodes by the degree of fat inclusions in midgut cells and in the fat body is developed. An "age scale" for the determination of the calendar age was assumed.

[Estimation of the biological age in males of the taiga tick (Ixodes persulcatus: Ixodinae) by fat reserves in the midgut].

Some criteria for the estimation of the biological and calendar age by the fat storage in midgut cells of Ixodes persulcatus males were established on the basis of examination of ticks from the laboratory culture.

[Age changes in Ixodes pavlovskyi (Ixodinae) natural populations from Novosibirsk and its outskirts].

The age structure of I. pavlovskyi natural populations from Novosibirsk and its outskirts was studied with the use of the fat reserves in the midgut and in the fat body as the age index.

[Formalin fixation in the method of the Ixodes persulcatus (ixodidae) age estimation by the state of fat reserves].

Formalin fixation is proved to be the useful tool in the method of age estimation for the taiga ticks collected in field. Formalin does not deform fixed material and does not dissolve fat; hence, it is the best fixing fluid when tick age is estimated by the state of fat reserves in its organism. The ticks preserved in 9% formalin were shown to be suitable for age estimation 1.5-2 months after fixation.

[PCR identification of DNA of hosts of the taiga tick nymphs (Ixodes persulcatus: Ixodinae) in St. Petersburg and its suburbs].

PCR identification of host DNA in unfed females and males of taiga tick Ixodes persulcatus was performed. Amplification of each sample was done using primers species-specific by 12S rDNA mitochondrial gene. Four species of small mammals (Apodemus uralensis, Clethrionomys glareolus, Microtus arvalis, and Sorex araneus) and two passeriform bird species (Fringilla coelebs and Parus major) were analysed. For one third of tick samples, hosts of previous stages were established using this method. In five cases, feeding on more than one host species was detected.

[Estimation of the biological age in taiga tick females (Ixodes persulcatus:Ixodidae) by the fat reserves in organism].

The method of estimation of the biological age in non-feeding tick females by the level of adipose inclusions in the cells of the midgut and fat body is developed. In order to estimate the fat reserves in non-feeding females, alive ticks were dissected and fragments of their internal were vitally stained with the pregnant solution of sudan III in 70 % ethanol. Three age-specific groups were established: I, young females whose intestines and fat body were filled with fat inclusions; II, mature females whose fat reserves were partially expended; III, old females having isolated fat inclusions in their midgut and fat body.

[Morphofunctional changes in the midgut of ticks of the genus Ixodes (Acarina: Ixodidae) during life cycle].

Morphofunctional investigations of five Ixodes species (Ixodes pacificus, I. pavlovsky, I. persulcatus, I. ricinus and I. scapularis) were carried out. It was established, that the change of midgut epithelium lags at the each next developmental stage, and it is not synchronized with general processes of metamorphosis and organogenesis during molts. The midgut epithelium of a previous phase of the life cycle persists and functions during the feeding stage at the next phase.

[Estimation of the biological age in females of the taiga tick Ixodes persulcatus by changes in the body shape and surface of cuticle].

A method of visual estimation of the biological age of living hungry tick females by visible changes in the depth of marginal groove and the structure of the alloscutum cuticle during natural ageing is developed. In recently activated individuals, the body is convex and the marginal groove is exposed, demonstrating distinctly visible cuticular microfolds (Figs 1-4). In attenuated ticks, the body is flattened and marginal fold overlays the marginal groove, concealing cuticular microfolds (Figs 5-8).

[Morphofunctional changes, and their significance, of salivary glands of ixodid ticks of subfamilies Ixodinae and Amblyomminae (Acari: Ixodidae) during nutrition].

By methods of light and electron microscopy, dynamics of functioning of salivary glands has been studied in female ticks of the genus Ixodes. Based on literature data and on our own studies, a comparative analysis of morphofunctional changes and of role of salivary gland secretion has been performed in female ticks of subfamilies Ixodinae and Amblyomminae in the process of nutrition.

[Structure of populations and ecological nishes of ectoparasites in the parasite communities of small forest mammals].

The paper reports the results of eight-year investigations on the ectoparasites of rodents and insectivores carried out in southern taiga of the Ilmen-Volkhov lowland (Novgorod Region) and Kurgolovsky reserve (Leningrad Region). Twelve species of small mammals were captured including three dominate species--bank vole Clethrionomys glareolus (2722 specimens), common shrew Sorex araneus (1658 specimens), and wood mouse Apodemus uralensis (367 specimens). Parasite community of the bank vole comprises 34 species of mites, ticks, and insects, the community of common shrew comprises 25 species, and the community of A. uralensis includes 28 species. Taxonomic diversity of the ectoparasite communities was shown to be based on the diversity of types of parasitism and ecological nishes of the host body. Permanent ectoparasites are found to be represented by 2 species of lie and 14 species of acariform mites. The group of temporary parasites includes 13 species of fleas, 10 species of gamasid mites. 3 ixodid species and 1 Trombiculidae. There is a common pool of temporary parasites of small mammals in the ecological system of taiga. Significance of different shrew and rodent species as hosts were found to be dependent on the population density in possible hosts and many other factors. Species diversity in the parasite communities of different small mammal species is dependent on the number of possible ecological nishes in the host body. Actual infill of these nishes by ectoparasites is usually lesser than potential one. Species composition of temporary parasites, their occurrence and abundance changes according to season. Interspecific competition in the temporary parasite species can decrease because of the seasonal disjunction of their population peaks. Diversification of the ecological niches of ectoparasites allow simultaneous feeding of more parasite individuals on one host, than in the case of parasitising of single species or several species with similar ecological nishes. The distribution of parasites on their hosts was also studied. The aggregative distribution has been found in ixodid larvae only, and the distribution of fleas was close to the Poisson distribution. Deviations from the aggregative distribution can be an effect of several independent factors, including limited ability of small mammals for providing numerous parasites with food. On the most part of hosts simultaneous parasitizing of no more than 1-3 individuals of each tick, mite, and flea species was registered. Excessive infestation by ectoparasites may probably be limited by effective reactions of self-purification in the mammal hosts.

[Skin lesions in small mammals parasitized by Psorergates apodemi and P. dissimilis (Gheyletoidea: Psorergatidae)].

Histopathology in the sites of localization and parasiting of the mites Psorergates apodemi Fain et al., 1966 and P. dissimilis Fain et al., 1966 on the Ural field mouse Apodemus uralensis (Pallas) and the bank vole Clethrionomys glareolus (Schreber) is described. The mites affected all epidermis cell layers down to the cambium layer and caused hyperkeratosis.

[Morphofunctional changes in the midgut of the Ixodes ricinus nymphs (Acari: Ixodidae) during developmental diapause].

Changes in the midgut of the Ixodes ricinus nymphs at the stage of developmental diapause were studied. It is established, that the midgut of the tick nymphs undergoes the identical and synchronous changes at the development without diapause and in the state of diapause. In 7-8 months after feeding the midgut of the nymphs containes the digestive cells with gematine and food inclusions, as well as reserve cells, like the midgut of unengorged moulted female. But the midgut of diapausing nymphs retaines such condition during the whole period of diapause.

[Morphofunctional changes in the midgut of the Ixodes females (Acari: Ixodidae) during the immunizing feedings].

The changes of the midgut in the females of the tick species Ixodes persulcatus and I. ricinus during the second and third immunizing feeding on rabbits were studied by the histological technics. The alternation of one generation of the digestive cells of nymphal stage and two generations of the digestive cells of adult stage was observed. The generation of secretory cells is absent. The tick completes feeding and drop off when the last generation of the digestive cells is on the initial activity stages. The amount of the blood consumed is not enough for the rhythmical functioning of the midgut. The feeding of tick is broken on the second phase and full satiation does not take place. It is apparently an effect of the interruption of the blood entrance into the midgut cavity of feeding tick as a probable result of anti-ticks resistance of unnatural hosts.

[Morphofunctional changes in the midgut of virgin tick females of the genus ixodes (Acarina: Ixodidae) during and after feeding].

The midgut epithelium of the virgin females in Ixodes ricinus, L. pacificus, and I. persulcatus is represented by the digestive cells of nymphal phase and stem cells. Digestion of feed is performed by the one generation of digestive cells of nymphal phase and two generations of digestive cells of adult females. The generation of secretory cells and two generations of digestive cells are absent. The feeding of virgin females is not completed but interrupted in the second phase during the period of slow feeding and preparation of the intestine for the third phase.

[Morphofunctional changes in the midgut of tick nymphs of the genus Ixodes (Acarina: Ixodidae) during and after feeding]. / Morfofunktsional'nye izmeneniia kishechnika nimf kleshchei roda Ixodes (Acarina: Ixodidae) vo vremia i posle pitaniia.

The midgut epithelium of feeding nymph is represented by the digestive cells of larval phase. Digestion of the main part of feed is performed by the one generation of digestive cells of nymphal phase after detachment, during moult. This period precedes the apolysis. The generation of secretory cells is absent on the nymphal phase. Secretory vacuoles are formed in the digestive cells of larval phase. All functioning cells form a peritrophic matrix on their apical surface. The replacement of the digestive cells of larval phase by the digestive cells of nymphal phase proceeds gradually, during the first 5-10 days after detachment. The beginning of the accumulation of digestive inclusions in the young digestive cells of nymphal phase takes place in the 10-15 days after detachment.

[Peritrophic matrix in the midgut of tick females of the genus Ixodes (Acari: Ixodidae)]. / Osobennosti peritroficheskogo matriksa v kishechnike samok kleshchei roda Ixodes (Acari: Ixodidae).

The formation of the peritrophic matrix in the midgut of females of 5 ixodid tick species (Ixodes pacificus, I. pavlovskyi, I. persulcatus, I. ricinus and I. scapularis) was studied by means of light and electron microscopy in different periods of the feeding and after detachment. The formation of the peritrophic matrix started when the first food portions came into the gut lumen, 9-12 hours after the attachment. Renovation of the peritrophic matrix took place during the whole feeding period; every new generation of midgut cells synthesized their own matrix. It was deposited on the apical surface of every midgut cell in the beginning of differentiation, and was functioning during the life of the cell. The peritrophic matrix separates spaces of the cavitary and cytozoic digestions.

[Morphofunctional changes in the midgut of tick females of the genus Ixodes (Acari: Ixodidae) during and after feeding]. / Morfofunktsional'nye izmeneniia srednei kishki samok kleshchei roda Ixodes (Acari:Ixodidae) vo vremia i posle pitaniia.

Cyclic changes of the midgut epithelium were observed in females of 5 ticks species of the genus Ixodes during 7-10 days of feeding. The midgut epithelium of unfed females is represented by the digestive cells of nymphal phase and stem cells. The digestive cells of nymphal phase are functional during 1.5-2 days after attachment of the tick, and then, after the tearing away they go into the gut lumen. The secretory cells substitute the digestive cells of nymphal phase and finish their growth during the 4-4.5 days. Secretion of digestive enzymes is performed by the holocrine type with tearing away a whole cell. Intracellular digestion takes place in the digestive cells of four consequent generations. The secretory and digestive cells form a peritrophic matrix on their surface. The presence of peritrophic matrix gives an evidence the maturity and functional activity of the secretory and digestive cells. We suggest, that the peritrophic matrix takes part in intracellular digestion, namely in the process of micropinocytosis. The phagocytosis was not found in the ticks investigated. Digestion in the midgut lumen is performed by enzymes of the ruptured secretory and digestive cells, that is proved by the haemolysis of erythrocytes in the zone of their contact with these cells. The digestive cells of each generation functioned almost synchronously, with largest difference in starting about 12 hours.

[Histopathological changes in lizard skin (Reptilia: Lacertidae) in feeding places of ticks of the genus Ixodes (Acari: Ixodidae)]. / Gistopatologicheskie izmeneniia kozhi iashcherits (Reptilia: Lacertidae) v mestakh pitaniia kleshchei roda Ixodes (Acari: Ixodidae).

Histopathological changes in a skin of Lacerta agilis in the places of attachment and feeding of nymphs of Ixodes pacificus and I. ricinus were investigated. The mouthparts of ticks are surrounded by the fibrin cone and collagen capsula formed by their hosts. Ticks of these species do not produce the cement. A proliferation stage of skin inflammation is expressed, the large collagen capsula is formed as the result of proliferation. Neutrophils and eosinophils predominate in the inflammate cell infiltrate.