Vol 57, No 2 (2023)

Different hypotheses on the origin of ixodid ticks, vectors of numerous dangerous transmissive diseases of humans and animals are analyzed basing on literary and partly own data. According to latest molecular-genetic and paleontological data, pro-ixodid ticks appeared not in mid-Mesosoic, as it was believed earlier, but most likely in the middle of Devonian. Among Parasitiformes, mites of the order Holothyrida Thon, 1905 form the most closely related to Ixodidae sister group.

The dominant zonal rodent species in the steppes and semi-deserts of the Caspian Lowland is the small ground squirrel Spermophilus pygmaeus (Pallas, 1778). Flea species, which are its specific ectoparasites, play a significant role in the occurrence of plague epizootics in this area. The impact of global climate warming on the population dynamics of the fleas of the small ground squirrel in the northern deserts on the territory of the Caspian Lowland is discussed in this article. The literature sources and extensive archival materials were used for the analysis. The Ilmen-Pridelta landscape region (southwest of the Astrakhan Region), which is most fully characterized through the necessary quantitative indicators, was chosen as a model territory. The data of the annual spring-summer registration of indices of the flea abundance in wool and at the entrances of the burrows of the small ground squirrel, as well as his abundance rates (number of specimens per 1 ha), average monthly air temperature values reported by meteorological stations in Astrakhan over the past 70 years were statistically processed. The article reveals the mechanism of the influence of contemporary climate warming on the dynamics of the number of fleas of the small ground squirrel in the territory of the Caspian Lowland over the period of 1950-2021.

The Transcaucasian highland vole natural plague focus is located within the Javakheti-Armenian (Javakheti and Armenian) Highlands and the Lesser Caucasus. In this region, rodents are hosts for fleas of 42 species from 21 genera. The one third part of flea species are monoxenous, the remaining species are oligoxene or pleioxene parasites. Fleas of 24 species are represented throughout the focus. Others are confined either to the Armenian or the Javakheti Highlands, as well as to the Lesser Caucasus. On the territory of the Transcaucasian focus, the warm period of the year is the most favorable time for the transmission of the plague, since fleas - parasites of the common vole - are characterized by high activity of nutrition and reproduction during this period.

The genus Haemaphysalis includes 168 tick species recorded in Europe, Asia, Africa and Australia. Within the Russian Federation 15 species of Haemaphysalis genus are endemic to different forested habitats in the south of European part and south of the Far East. H. japonica tick is common in Japan and on the continental part of South-Eastern Asia, including the Russian Maritime Territory. The continent al population is referred to the subspecies H. japonica douglasi. In Russia it is common in Amur Region and Primorye. This communication is devoted to five findings of the tick in Irkutsk region (East Siberia). The findings were recurrent during the same season and the same route, suggesting the idea of micropopulations of H. japonica douglasi existing in our region.