Archive

Indication of Borrelia (В. burgdorferi sensu lato) in 205 adult unfed I. persulcatus ticks from a natural focus was carried out simultaneously by methods of PCR and dark-field microscopy of vital preparations. PCR method revealed Borrelia prevalence in considerable number of ticks, in which were not found by microscopy of 250 microscopic fields in a preparation from each individual tick. At the same time, PCR method didn't give positive results for approximately 8% of ticks, which contained rather high concentration of Borrelia (more than 10 per 100 microscopic fields). In general, PCR method doesn't have advantages in comparison with a microscopy of vital preparations for study the Borrelia prevalence in ticks.

The phenomenon of the parallel evolution is considered with the example of the myobiid mites (Acari: Prostigmata: Myobiidae) and the jerboas (Rodentia: Dipodoidea). According to recent phylogenetic studies of the superfamily Dipodoidea it is separated into 4 family: Allactagidae, Dipodidae, Zapodidae and Sminthidae (Shenbrot e. a., 1995). The myobiid mites of the subenus Dipodomyobia (11 species) of the genus Cryptomyobia are known as specific parasites associated with jerboas of the families Dipodidae and Allactagidae. One more species (Radfordia ewingi) considered as incertae sedis species within the genus Radfordia is found on the jerboas of the family Zapodidae. The myobiid mites are apperently absent on the members of the family Sminthidae. The reconstruction of phylogeny of the myobiid subgenus Dipodomyobia was carried out by the cladistic method (software PAUP 3.0s). The analysis was based on 13 morphological characters. At the first step of analysis 42 parsimonious trees have been obtained. The strict consensus tree displays one distinct cluster, which incorporates mites of the allactaga species of group restricted to the jerboa family Allactagidae, and several plesions, species of which are usually reffered to as dipi species group and associated with the family Dipodidae (fig. 1). At the second step of analysis, two characters, which appeared as homoplasies at the first step of analysis were excluded, and one new characters (structure of male genital shield) was additianally included. Single cladogram obtained displays two general clusters and one plesion. The first cluster comprises the allactaga species group (parasites of Allactagidae). The second cluster incorporates the dipi species group, the parasites of subfamilies Dipodinae and Paradipodinae of Dipodidae). The plesion is represented by one species Cryptomyobia baranovae being a specific parasite of Salpingotus crassicauda (Cardiocraninae, Dipodidae). There is the high level congruence between the pattern of myobiid cladogram and jerboas phylogeny proposed by Shenbrot (1992) (fig. 2). The position of one species C. paradipi (the parasite of Paradipus ctenodactylus, single representative of subfam. Paradipodinae) does not fit to this phylogenetic system of the jerboas. This mite species belongs to the claster dipi. All others myobiid species of this group are the parasites of the subfamily Dipodinae. In the cladogram of jerboas, the subfam. Paradipodinae is a sister group of Cardiocraninae, but not of Dipodinae, as it is suggested by the parasitological data. If sinapomorphies in the node Paradipodinae — Cardiocraninae are not correct (as Shenbrot admitted), there would be a complete congruence between the phylogenetic pattern of myobiid and of jerboas. The general phylogeny of Dipodoidea based on citogenetical data was proposed by Vorontsov e. a. (1971). 3 families only were recognized within Dipodoidea: Zapodidae, Sminthidae and Dipodidae. The latter family included 3 subfamilies: Dipodinae, Cardiocraninae and Allactaginae. The version of the jerboa phylogeny proposed in the present paper based on parasitological data corresponds in general lines to the hypotesis of Vorontsov e. a. (1971). The myobiid mites are absent on Sminthidae, they are represented by one species incertae sedis on Zapodidae, and by the subgenus Dipodomyobia on others jerboas (Dipodidae sensu Vorontsov e. a.). According to the parasitological data, the subfamilies Dipodinae and Allactaginae are the sister groups, because the myobiid mites of the subgenus Dipodomyobia parazitise on the jerboas of these taxa only. The subfamily Paradipodinae (sensu Shenbrot) is a sister group for Dipodinae, as far as species C. paradipi is the sister species to other members of the dipi group. The subfamily Cardiocraninae is a sister group for the node Dipodinae — Paradipodinae and also should be included to Dipodidae, because the aberrant species C. baranovae is obviously related to the dipi species group.

Numbers of scutal, coxal and sternal setae were counted in 1393 specimens of 5 Hirsutiella species. All observed chaetotactic anomalies were classified into 3 groups: 1) "rare" anomalies, such as absence of one AL, AM, coxal or sternal setae, presence of additional AL, AM, coxal or anterior sternal setae; 2) presence of 1—2 post-posterolateral soutal setae (PPL); 3) presence of additional 1—3 posterior sternal setae. "Rare" anomalies were found in 2.8% of the specimens examined. They were observed usually in northern or alpine populations. Obviously, it is an effect of more frequent ontogenetic failures in rigorous climate conditions being out of optimum for trombiculids. The quota of the individuals with PPL in a set of H. steineri samples varied from 16 to 74%, while in the other samples of this species the presence of the single (and not more) PPL were found very seldom, as well as in the other species examined. In the similar way, the additional posterior sternal setae were found with the frequency up to 100% in the some samples of H. steineri, H. hexasternalis and H. alpina, but in other ones they were present only in few specimens. Since in a series of cases the ratio of the number of specimens with PPL to the number of specimens without PPL, as well as the ratio of the number of specimens with fSt = 2.4 to the number of specimens with fSt = 2.2 is almost equal to 2, one can suppose that the variance of this characters has a genetic basis. All samples having a high frequency of the PPL appearance or the appearance of additional posterior sternal setae were collected in the alpine zone. It is an evident example of the ecogeographical rules, which were reported previously by the author for the quantitative characters in species of the genera Neotrombicula (Stekolnikov, 1996, 1998, 1999) and Hirsutiella (Stekolnikov, 2001). It is possible that the PPL appearance is caused by the higher humidity of the climate, and the appearance of additional posterior sternal setae — by the low temperature. It is supported by the fact that the samples with high friquency of individuals having PPL are specific to damp areas of Western Caucasus, while the populations with high frequency of additional posterior sternal setae appear to be characteristic for regions with more dry climate (Daghestan, Turkey, Chelyabinsk Region of Russia). The fact, that in some populations of H. steineri, the individuals having PPL are prevalent, can serve as a serious argument for the abolishment of the genera Hoffmannina Brennan et Jones, 1959 and Aboriginesia Kudryashova, 1993 distinguished from related groups only by the presence of this setae.

Peculiarities of geograpfical distribution and distribution among hosts of the haemosporidian parasites, which couse lethal diseases in poultry, are specified. So far, 11 species of such parasites have been described. This represents about 5% of bird haemosporidian parasites. The haemospori-dians cause the lethal epizooties in turkeys, chickens, ducks, geese, pigeons and domesticated ostriches. One species of parasites belongs to the family Haemoproteidae, six — to Plasmodiidae, and four — to Leucocytozoidae. The agents of lethal haemosporidioses have been recorded in domestic birds of the orders Galliformes, Anseriformes, Columbiformes and Struthiorniformes. The majority of these parasites (eight species of 73%) occurs in the galliform birds. Each other order obtaines only one species of parasites. Five species parasitize turkey, which is the main host of the agent of lethal haemosporidioses. The majority of highly virulent haemosporidian species have been recorded throughout a global territory, which includes the Holarctic, Ethiopian and Oriental zoogeorgaphical regions. Three species of these parasites have been found in the Neotropical region, while none species has been recorded in Australia. The majority of highly virulent haemosporidian species have quite clear outlined areas, that is important to know for the prophilactic purposes including the quarantine of bird introducing from endemic terrritories.

Different classification of the phylum Microsporidia (Sprague, 1977; Weiser, 1977; Issi, 1986; Sprague, Becnel, Hazard, 1992) are briefly discussed. New taxa (families Glugoididae, Flabelliformidae, Neopereziidae, Rectosporidae and superfamilies Encephalitozoonoidea, Cylindrosporoidea) are proposed in the new classification of Microsoridia.

The comparative analysis of the ultrastructure of various types of parasitophorous vacuoles (PV) induced by microsporidians is given. The data on the occurrence of PV in the hosts belonging to different systematic phyla are summarised. It is concluded, that the formation of PV around microsporidians might take place either in certain parasite species or in the special type of the invaded cells, or could be connected with the development in the unspecific host. The variety of fine structure of PV might be explained by an extremely broad range of hosts (from protists to mammalians), with different level of development of their immune system (defence reactions). Three basic types of PV are proposed according the organization of their envelopes (walls): (1) a single membrane originated from the host cell plasmalemma (hosts: Aves and Mammalia); (2) a single membrane derived from the host ER (hosts: Pisces); (3) a single- or double-membrane host ER (hosts: protists, invertebrates and animals of other systematic groups). It was assumed that the formation of the PV around microsporidians reflects more primitive host-parasite interactions, than the development of the parasite in a direct contact with the host cell cytoplasm.

The influence of the T. nodulosus plerocercoid invasion on the liver of the intermediate fish hosts (perch) was studied. The water, protein, glycogen and glucose contents was examined in adult worms inhabiting the intestine of definitive hosts (pike), the rate of glucose accumulation along the strobile of parasite and an ability of adult worms to hydrolyze the main nutrients was also investigated. As a result of the plerocercoid infection, the glucose and glycogen contents in the liver of perch juveniles decreased, while the wet weight of liver increased. It was found, that the water and protein contents from the anterior to posterior section of strobile in T. nodulosus adults was not significantly different, while the glucose contents and the rate of its accumulation decreased. The data confirming the possibility to realize the final stages of protein and carbohydrate hydrolisis with the participation of membrane digestion on the surface of helminths and proving the ability of cestodes. The problems of relations of T. nodulosus with intermediate and definitive hosts at the level of the whole organisms are discussed.

The influence of temperature and salinity on the survival of free-living cercariae of the marine trematodes Podocotyle atomon and Renicola thaidus has been examined. It was found out, that the survival of free-living cercariae depend upon the temperature and salinity of the water.

The canines have been investigated during 19 year (1980—1998) in the Belorussian Polesie in realtion to their infection with the trematode Alaria alata (Goeze, 1782). Four species of canines (Canis familiaris, C. lupus, Vulpes vulpes and Nyctereutes procyonoides) have been recorded as definitive hosts. A significance of meliorative channels as potentian foci of the alariasis infection is considered for the first time.

In the Kandalaksha Bay (White Sea), the experiments have been carried out to study the life cycle of the larval trematodes of the genus Himasthla (Dietz, 1909) from the intertidal whelk Littorina saxatilis. It has been established that the blue mussel, Mytilus edulis, is the second intermediate host for this species. The seagull Larus canus is the final host. The species has been identified as Himasthla elongata.