[Demography and population models of ticks of the genus Ixodes with long-term life cycles].

The most important parameters necessary for the creation of population models for threehost species with long-term life cycles are discussed with an example of ticks Ixodes persulcatus and I. ricinus. In these species, specimens of the same biological age may belong to different age cohorts and their calendar age may differ by several months or even years. Accurate estimation of the calendar age of separate individuals is dofficult; it is based on the extrapolation by its possible biological age and by belonging to the certain age cohort of a natural population. Population models that can predict simultaneous abundance of activated hungry specimens of all the three developmental stages and probability of host-finding in hyngry ticks during questing period possess the prognostic value. Daily mortality of ticks of different developmental stages and phases of each stage (questing, feeding, preparation for molting, and diapause) must also be known. The abundance of questing hungry ticks in the ecosystem is determined by the balance between recruitment of the population with new individuals, their selection by hosts, dying of ticks from starvation, and consumption of ticks by predators. At present, unfortunately, only some of these parameters are known rather sufficiently.

[Parasitism and ecological parasitology].

Parasitism as one of the life modes is a general biological phenomenon and is a characteristic of all viruses, many taxa of bacteria, fungi, protists, metaphytes, and metazoans. Zooparasitology is focused on studies of parasitic animals, particularly, on their taxonomy, anatomy, life cycles, host-parasite relations, biocoenotic connections, and evolution. Ecological parasitology is a component of ecology, as the scientific study of the relation of living organisms with each other and their surroundings. In the present paper, critical analysis of the problems, main postulates, and terminology of the modern ecological parasitology is given.

[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.

[To 70th anniversary of E. N. Pavlovsky's theory on the natural nidality of human diseases].

For 70 years of the development of concept of the natural nidality of human diseases many its initial postulates undergo considerable changes, while its essence remain the same. Many "new" infections with natural foci were discovered and their geographic distribution was investigated in detail, classification of natural foci was developed. It was established, that epidemic features of transmissive infections depend mainly on the types of parasitism of their insect, tick and mite vectors.

[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).

[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.

[The origin and evolution of parasitism on terrestrial vertebrates in insects, mites, and ticks].

Coexistence of terrestrial vertebrates and arthropods has been continuing over 200 million years; various forms of parasitism originated independently in various groups of arthropods during this period. The association of Acari and insects with nests and shelters of their hosts (nidicoly) played the main role in the origin of parasitism in these major groups of arthropods. The primary step in the evolution of parasitism was the permanent habitation in nests and borrows of mammals and birds in Mesozoic era. The second step was a substitution of various forms of schizophagy by the regular feeding on products of vital activity and dead parts of host body. The next step was the feeding on various body parts of vertebrate hosts, namely skin, hair, feathers, external excreta, and drops of blood. The final step was the development of the ability to damage skin and suck out the blood of vertebrates. In some taxa of astigmatid mites the parasitism on birds originated from phoresy: hypopi (heteromorphous deutonymphs) obtained the ability to absorb the liquid nutrients from hair follicles and subcutaneous tissues through the cuticle. The development of haematophagous feeding on mammals in several families of Diptera was the second way of the origin of parasitism. Highly mobile dipterans with the piercing-sucking or licking mouthparts were able to change easily from the accidental puncturing of the host skin or licking of the blood, pus, and mucus to the obligatory haematophagy. The evolution of some arthropod taxa did not went beyond a primary domination of spatial relations, as in many astigmatid mites, or trophic relations in the form of micropredatory, as in the haematophagous Diptera.

[An algorithm for synthesis of small-size autonomous devices for detection of medico-biological parameters].

Problems of synthesis of devices for detection of medico-biological parameters are considered. A classification of the devices and their functional units is proposed. An algorithm for synthesis of detectors of medico-biological parameters on the basis of multiple-use functional units is suggested. The algorithm is based on analysis of functional unit modifications providing optimization of the device characteristics.

[Ecological niches of ectoparasites].

On mammals and birds communities of ectoparasites are present, which can include scores of ticks, mites and insects species. The parasitizing of arthropods terrestrial vertebrates appeared as far back a the Cretaceous period, and after 70-100 mil. years of the coevolution ectoparasites have assimilated all food resources and localities of the hosts' bodies. To the present only spatial and (to the less extent) trophic niches of parasitic insects, ticks and mites are studied completely enough. The main results these investigations are discussed in the present paper. A high abundance of the communities is reached because of their partition into the number of ecological niches. Host is complex of ecological niches for many ectoparasites species. These niches reiterate in the populations of a species closely related species of hosts and repeat from generation to generation. The each part of host (niche) being assimilated be certain parasite species is available potentially for other species. The partition of host into ecological niches is clearer than the structure of ecosystems including free-living organisms. A real extent of the ecological niches occupation by different species of ticks, mites and insects is considerably lower than a potential maximum. The degree of ecological niches saturation depends on the history of the coevolution of parasites community components, previous colonization be new ectoparasite species and many other ecological factors affecting host-parasite system. The use of the ecological niche conception in parasitology is proved to be rather promising. Ectoparasites communities because of their species diversity, different types of feeding and a number of habitats on host represent convenient models and study of them can contribute significantly to the developmeht of the general conception of ecological niche.

[Structure of parasitic arthropod communities in forest small mammals]. / Struktura soobshchestv paraziticheskikh chlenistonogikh melkikh lesnykh mlekopitaiushchikh.

Species composition and structure of ectoparasite arthropod communities were examined all year round six years in the bank vole Clethrionomys glareolus, Ural wood mouse Apodemus uralensis and the common shrew Sorex araneus in forests of the Ilmen'-Volkhov depression. In total, 4500 host samples have been examined and all ectoparasites have been collected. The species composition of ectoparasite community in small mammal species are as follows: the bank vole--29 insect, tick and mite species, the common shrew--23 species, the Ural wood mouse--16 species. In forest biotopes, many temporary ectoparasitic species occur on several host species living in the same habitats under a forest canopy and contacting each other. A parasitic supracommunity in the ecosystem examined has a pool of temporary ectoparasites, which is available for all the community of small mammals. A role of different rodent and shrew species are hosts of insects and ticks changes depending on a density of potential host populations and numerous other environment factors.

[Academician E. N. Pavlovskii's parasitology school in the Zoological institute RAS]. / Parazitologicheskaia shkola akademika E. N. Pavlovskogo v Zoologicheskom institute RAN.

The first parasitological division in the Zoological Museum was created in 1924 by the initiative of E. N. Pavlovsky and A. A. Schtakelberg and originally had a named "The permanent commission on the study of malaria mosquitoes". In the process of reorganisation of the Zoological Museum into Zoological Institute in 1930, it was modified into the Department of Parasitology with the E. N. Pavlovsky as a head. In 1934-1935, two laboratories were formed within this department: the Laboratory arachno-entomology and Laboratory of parasitic worms. In subsequent history of ZIN, these parasitological laboratories existed at first as subdivisions of the Department of Parasitology and finally the they were reorganised into independent administrative divisions. The study of parasitic and blood-sucking arthropodes is concentrated in the Laboratory of Parasitology (the head Yu. S. Balashov). A creation of the most important concepts of ecological parasitology was taking place in the Zoological Institute in the middle of 30th. E. N. Pavlovsky for the first time had formulated the principle of an organism as an environment for parasites, the concept of communities of parasitic organisms (concept of parasitocoenosis), and the theory of natural focuses of transmissive diseases. In the process of development of these scientific generalisations, a scientific direction named "Academician E. N. Pavlovsky's school of thought in parasitology" was formed in the USSR in 40-50th. In the frame of this school of thought, the main tusks of the Laboratory of Parasitology ZIN are to work out fundamental problems in ecology, systematics and morphology of parasitic and blood-sucking ticks, mites and insects. Within the ecological parasitology, different aspects of host-parasite relationships are studied at organism and population levels. The main basis of systematics studies of parasitic arthropodes is a scientific collection including over 250,000 samples. Based on this material, 40 key books and monographs on the USSR's fauna were created. Over 20 doctors of science and 50 candidates of science have been prepared within the laboratory or under the promotion of its stuff during 70 years of the existence of the Laboratory of Parasitology.

[Structure and seasonal dynamics of an ectoparasite community on the common shrew (Sorex araneus) in the Il'men'-Volkhov lowland]. / Struktura i sezonnaia dinamika soobshchestva éktoparazitov obyknovennoi burozubki (Sorex araneus) v Il'men'-Volkhovskoi nizine.

Species composition, seasonal dynamics, and a load of ectoparasites per individual and population of the common shrew Sorex araneus have been examined in coniferous and mixed forests of the Ilmen'-Volkhov lowland (a neighbourhood of Oskuy village, Chudovo district, Novgorod Province) during the period 1999-2003. Trapping of mammals was carried monthly, with exception of few accidental gaps. The Gero traps were used for catching micromammalian hosts. The lines of trap were checked 2 times a day, places of lines changed each 3-5 day. Total number of micromammalians collected during the period of study is 3215, including 1115 specimens of the common shrew S. araneus and 246 ones of the pigmy shrew S. minutus. Parasite fauna on the common shrew included 23 ectoparasite species: fleas--12, ixodid ticks--2, gamasid mites--7, and myobiid mites--2 species. Among recorded species, 9 fleas species and some gamasid species are accidental parasites. These accidental ectoparasite species are common to the bank vole Clethrionomys glareolus in the territory investigated. Species composition, occurrence and abundance indices of parasites changed during the year. In total, about 55% shrew specimens are infected with ectoparasites. The infracommunity of ectoparasites on the common shrew usually consists of 6 species or less. Mean number of all ectoparasite individuals per one host specimens varies from 4 to 83. The greatest number of parasites (50 and 83) was recorded on the shrews, which carried 5 and 4 parasites species, respectively. Biodiversity of parasite species in the ectoparasite community on the common shrew and the load of parasites per one host specimen are lower than those in the bank vole. In forest biotopes explored, the most part of temporary ectoparasite species found on the common shrew was also recorded on other small mammals, which could have contacts with this host. It is possible to conclude that among the parasite supracommunity in the explored ecosystem, the temporary ectoparasites represent a "fond" of temporary parasites, which are common for most small mammal species. A role of different shrew and rodent species as main of additional hosts changes depending on a population density of potential mammalian hosts and other environment factors.

[Structure and seasonal dynamics of the biotic community ectoparasites of the bank vole in the Il'men'-Volkhov lowland]. / Struktura i sezonnaia dinamika soobshchestva éktoparazitov ryzhei polevki v Il'men'-Volkhovskoi nizine.

A biodiversity, seasonal dynamics and parasite load of a single individual and local population of the bank vole (Clethrionomys glareolus) were studied in coniferous and mixed forests of the Ilmen-Volkhov lowland (neighborhood of Oskuy village, Chudovo region, Novgorod Province) in the period from June 1999 till May 2002. The Gero's traps were used for collecting the host. Lines of traps stood in each place during 3-5 days and were checked twice a day. Trapping of micromammalian hosts and collecting of parasites took place each month, except a few gaps. Total number of collected animals 2854 including 1405 bank voles. The 29 ectoparasite species were recorded on the bank vole in the area of study. Among some mites and fleas a few species are accidental parasites probably accepted by voles from other species of animals. In the Oskuy area, the bank voles are the main and additional hosts of 25 ectoparasite species: fleas--8, lice--1, ixodid ticks--2, gamasid mites--7, acariform mites 7. Species composition of ectoparasites, their occurrence and abundance change during the year. Seasonal changes of abundance and occurrence indices are most expressed in the temporary ectoparasites (ixodid ticks, chiggers, gamasid mites), while in the permanent parasites (lice, acariform mites: Myobiidae, Myocoptidae, Listrophoridae), the seasonal fluctuations of indices are displayed in a less scale. Most vole specimens were infected with this or that ectoparasite species. The parasitocenosis on an individual specimen usually included less than 10 species of the total number 29 species recorded on the bank vole in the area investigated. One ectoparasite species was recorded on 21% of host specimens, 2-5 ectoparasite species were found on 71% of host individuals. Maximal number of ectoparasite species (10 species) was registered on one specimen only. The parasite load was dispersed unevenly among the infected voles. Mean number of parasites of all species on a host individual varied from 124 to 295. The highest grade of parasites (237-297 parasite specimens) was found in the voles with 7-10 species of parasites.

[Specificity of host-parasite relations between arthropods and terrestrial vertebrates]. / Spetsifichnost' parazito-khoziainnykh sviazei chlenistonogikh s nazemnymi pozvonochnymi.

Specificity of partners in host-parasite system is one of its main characteristics. Unfortunately this term has different senses in scientific literature. In everyday practice one judges an extent of host specificity of a parasite mainly by indices of its occurrence and abundance on different host species. An occurrence of parasites in nature reflects general result of complex eco-physiological interrelationships between partners in hostparasite system. Specificity of parasites in a choice of hosts may depend on a belonging of the latter to certain taxa (phylogenetic specificity), or on biotic and abiotic factors (ecological specificity). In arthropods, the phylogentic specificity and coevolution are characteristic to a greater extent for permanent hosts (lice, Mallophaga, cheyletoid and feather mites). A coevolutionaryphylogenesis is disturbed by transfers of parasites onto new hosts, by different rates of speciation in filial lines or by an extinction of several parasite taxa. In temporary parasites different forms of ecological specificity are prevalent. A host specificity is expressed to the lesser extent in mosquitoes, horseflies and in other blood-sucking Diptera. In temporary parasites with a long-term feeding (ticks) coevolutionary sequences are relatively rare, because this parasites had to adapt not only to a life on host, but also to a lesser stable environment. In some nest-burrow bloodsuckers (fleas, gamasid mites and argasid ticks) the ecological specificity is shown no by their relations with certain host species, but by an associations with habitats occupied by hosts (burrow, nests, caves). In relation with a high dynamics of host-parasite system, a specificity of its partners is comparative and it is kept up only under specific ecological conditions.

[Terms and concepts used in the study of parasite populations and communities]. / Terminy i poniatiia, ispol'zuemye pri izuchenii populiatsii i soobshchestv parazitov.

Russian terms commonly used in publications dealing with descriptions of habitats, populations and communities of parasitic animals and respective synonyms or similar concepts in English scientific papers are listed below. [symbol: see text] (biotope)--a land or aquatic area with uniform abiotic conditions occupied with certain biocoenosis.

[The role of blood-sucking ticks and insects in natural foci of infections]. / Rol' krovososushchikh kleshchei i nasekomykh v prirodnykh ochagakh infektsii.

During 60 years passed after the creation of the conception on natural focus of human infections by the academician E. N. Pavlovskii our knowledge on a role of blood-sucking insects and ticks in this phenomenon have been significantly enlarged. It has been recovered, that these arthropods serve not only as vectors of infection agents, but also as natural reservoirs and amplificators of these agents. In the process of the infection agent circulation in the natural focus there are several additional pathways of circulations without a participation of vertebrates. These pathways are as follows: the dispersion of infection agent in cases of simultaneous feeding of infected and "clean" ticks, and also the sexual, transovarial and transphase transmissions of pathogens. These mechanism of circulation are most often occur in the ixodid ticks, which can play the main role in supporting the infection agent in the focus.

[Transovarial and transphasic transmissions of Borrelia by the taiga tick Ixodes persulcatus (Ixodidae)]. / Transovarial'naia i transfazovaia peredachi borrelii taezhnym kleshchom Ixodes perculcatus (Ixodidae).

Three generations of the taiga tick Ixodes persulcatus, the descendants from naturally infected females, have been examined by means of dark field and phase contrast microscopies and indirect immunofluorescent reactions with monoclonal antibodies. Location of borreliae in oocytes was examined by means of electron microscopy. The examined ticks derived from 9 females collected in the Novgorod Province, from 6 females of 1st laboratory generation and 5 females of the 2nd generation. In total, 250 larvae, 178 nymphs, 59 females and 70 males of three consequent generation have been examined. Almost 100% of descendants of naturally infected females were infected with Borrelia burgdorferi s. l. and similar infection rate was observed in unfed tick larvae collected in field conditions. The borreliae received transovarially to larvae of the 1st generation then were transmitted to 100% nymphs and imago of this generation and two next generations.