Scientific journal
Fundamental research
ISSN 1812-7339
"Перечень" ВАК
ИФ РИНЦ = 1,749

Polyakov A.D.

Kuzbass region forest-steppe and taiga ecosystems are characterized by the complication and versatility. Tick focuses (focuses of tick-borne encephalitis) are one of the most principal elements of taiga ecosystems. The degree of taiga lands development is of great importance in tick focus formation. Ixodes persulcatus is the main component of tick focus and tick-borne encephalitis carrier.

Among rodents of squirrel family living in sets the following species of taiga tick hosts are established on the territory of Kuzbass: Asian burunduk (Tamias sibiricus), long-tailed suslik (Spermophilus undulatus), Spermophilus erythrogenys, Marmota baibacina and a forest-steppe marmot (Marmota kastschenkoi).

Earlier we shoved up a 36-chromosomal kariotipe in Marmota kastschenkoi. Forest-steppe marmot is the youngest species among them and diverged from M. baibacina due to chromosomal rearrangement (Brandler, 2002; Brandler, Boyeskorov, 2003).

Now epidemiologists should turn their special attention to burunduk and marmot. In connection with mass extermination actions towards suslik their number is insignificantly small on the territory of Kuzbass.

Asian burunduk as a typical taiga species is one of the basic universal host of ticks at all stages of growth in taiga formation. The marmot, due to it´s ecological plasticity, is capable to create mobile anthropurgic tick centres near to settlements. In Kuzbass it is protected everywhere, but at the same time the problem of prevention of its resettlement to man´s habitation should be solved.

The large group of small mammals are the hosts for larvae and nymph phases of Ixodes persulcatus growth (22 specieses of the small mammals) (Kalyagin, Polyakov, 1998; Polyakov, 2003).

Ixodes persulcatus exists everywhere even in forest-steppe and in steppe where woody and shrub vegetation is growing. But taiga type biocenosis is the main site of Ixodes persulcatus concentration. It is the most numerous species, practically all small mammals inhabiting the same area as Ixodes persulcatus are the hosts for its nymphs and larvae.

The phase of imago is fed up on the large wild mammals and birds. The pieces of tissue from belly with sucked ticks on them were fixed in 10 % formalin and were treated according to the standard methods (pieces washing from formalin, dehydration, covering with paraffin and cutting on microtome). Eyelids, lips and ears - the usual places of ticks sucking on mammals were free from ticks. The sections with thickness of 8-10 micrometers were being coloured by hematoxylin-eosin.

Anthropogenic transformation of taiga ecosystems begins and grows with taiga lands development. Transitional and zoonotic tick focuses begin appearing in place of primary taiga tick focuses. There remain Ixodes persulcatus carrier itself and the hosts for its larvae and nymph phases of growth i.e. the small mammals and birds in taiga ecosystems. The phase of imago turned to parasitize on the domestic animals. The primary tick focuses with the settled components are considered to be the most stable, their plenty and occurrence indices don´t reach considerable magnitude and are not exposed to severe fluctuations.

The zoonotic focuses present oneselves as the most unstable tick focuses.

Under conditions of primary focuses Ixodes persulcatus females are fed up on large wild animals. Ixodes persulcatus activity appears very early with the first thawed patches and is fluctuated depending on spring course reaching activity peak on the first ten-day period of June and gradually being reduced by the end of summer.

The ticks larvae, nimphs and imago (female) parasitism begins with mechanical destruction of ground squirrel derma by ticks oral cavities and with the forming of peculiar fixative apparatus (so called "cement etui") which is being formed from indurated saliva of taiga tick and it keeps them well on the animals derma during bloodsuction process of many days. On early stages of larvae, nimphs and imago bloodsuction considerable inflammatory infiltration is not to be observed in round squirrel derma. Perhaps it is bound up with saliva characteristics to detain inflammatory process coming and to secure free process of bloodsuction and the exchange by infections organisms. The phenomenon is to be observed both in single separate ticks parasitism and in plural one in different combinations (larva-larva, nympha-nympha, larva-nympha, larva-imago, nympha-imago, imago-inago), for all that age and sex of animal was not of particular importance. The next stages of ticks parasitism are characterized by emergence of weak (with larvae parasitism) and moderate (with nymphs parasitism) inflammatory infiltration in wound defect place, infiltration being accumulated by he end of parasitism.

Perhaps it is bound up with lowering and subsequent stopping of secretory activity of ticks (larvae, nymphs, and imago) salivary glands. At the same time the animation of regeneration process in epithelial derma is to be observed together with inflammatory process.

By the end of larvae, nymphs, and imago parasitism regeneration process, promoting passivevfalling taiga tick away from ground squirrel derma has been developed.

Researching inflammatory process proceeding in epidermis of various species of wild small mammals, with larvae, nymphs and imago taiga tick parasitizing on them, certain difficulties in determining of blood satiation degree and spase of time ectoparasite presence on hosts arise.

On histological preparations from the host tissue in places of tick suction epicuticle, hypoderma and intenstine cells are especially clear shown, therefore morphological changes of these signs have been used as criterion of blood satiation degree and space of time of presence of tick growth stages on mammal epidermis: 1) hungry, 2) started to blood sucking, 3) having sucked a considerable amount of blood, 4) completely sucked.

The intestines of hungry taiga tick female are covered with small poorly differentiated cells, the boundaries between them are not distinct. The intestine is flat.

During the second stage (1day) the boundaries between epithelium cells are shown up. The intestine lumen is clearly shown up. Those who sucked a considerable amount of blood (4-5 days) have the separation of macelike cells in the intestine lumen. The destruction of torn away cells takes place. The intestine walls of completely sucked females (6-8 days) are as much as possible stretched. The intestine lumen is overfilled with black-brown crystals of heme.

REFERENCES

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  2. Brandler O.V., Boyeskorov G.G. Karyotype evolution of some Palearctic species of Marmota (Sciuridae, Rodentia) //In European Mammology 2003. European Congress of Mammology, Brno, Czech Republic, July 27 - August 1, 2003. Abstracts". Brno, 2003. P. 72.
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