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This paper is devoted to the contributions of the outstanding parasitologist Yuri S. Balashov. It is not biographical. Its purpose is to highlight selected aspects of Yuri S. Balashov's scientific legacy that the authors consider most important for an international readership. This should direct the attention of international researchers to his various scientific theses and concepts, some of which have been only published in Russian language, and should also open up a broader discussion. The scope of Balashov's scientific interests was remarkable, although he devoted special attention to the research of argasid and ixodid ticks (Argasidae and Ixodidae). The main results and conclusions of his tremendous work have been described here using mainly his own words. Only some explanations that may be required to increase the reader's understanding of the concepts, terms and thoughts of Yu. Balashov were made by the authors.

Antimicrobial proteins and peptides (AMPs), essential components of the immune system, represent a diverse class of natural molecules produced by all living organisms in response to pathogen attacks. AMPs can possess a wide range of antibiotic activity against foreign and opportunistic bacteria, fungi, and viruses. AMPs play an important role in the selection of colonizing bacterial symbionts, which helps multicellular organisms to cope with certain environmental problems. AMPs are especially important for invertebrates due to the absence of an adaptive immune system. Although many AMPs have similar physical and chemical properties (common total length varying from 10 to 100 amino acids, total positive charge, or high cysteine content), their immunomodulatory activity is specific for each AMP type. The present review summarizes current state of knowledge on leech immunity, with emphasis on the special role of AMPs, and indicates the wide variety of primary AMP structures, which seems to correlate with a variety of life strategies and ecology of ectoparasites.

Detection and treatment of theileriosis is an important tool for controlling this disease. Wide range of Theileria spp. species, their species-specific characteristics, disease severity, and drug susceptibility determine the importance of accurate identification of the pathogen for epidemiological research and diagnostic purposes, taking into account the characteristics of their vertebrate hosts and arthropod vectors. The presence of many varieties of Theileria is an incentive for the creation of PCR test systems with an ability to identify different species, as well as to register coinfection. Modern methods of control detection and spreading of the disease do not always allow recognizing early stages; this fact, taking in account high transience of the disease, can contribute to losses in animal husbandry. Hence, the development of rapid and sensitive detection methods in the early stages of the disease causes interest. The present paper presents modern approaches to the molecular diagnostics of Theileria spp.

Data on differences in ecological needs of mosquitoes of different genera and species at different stages of the life cycle are important for the explanation of their distribution in regions with different climate and can also be compared with differences in their physiological characteristics. In the present paper, air temperature and humidity were measured in sites of maximum density of adult mosquito females of the genera Culex and Culiseta, overwintering in near-entrance parts of Sablino Caves (Northwestern Russia). Overwintering together, Culex females (predominantly Cx. pipiens) concentrated, in general, in warmer places than Culiseta females (mainly Cs. annulata). The mean difference in temperature between sites of maximum density of Culex and Culiseta females was 1.6 °C (p = 0.0039, Wilcoxon signed rank test; the Bayes factor in favor of alternative (BF10) was more than 40). In general, humidity was also higher in sites of maximum density of Culex females in comparison with those of Culiseta females - the mean difference constituted 9.4 % (p = 0.0051, the BF10 is more than 20). These results support a hypothesis on the different temperature and/or humidity requirements of Cx. pipiens and Cs. annulata: the latter species may be considered as better adapted to low temperature and/or low humidity. Probably, when temperature and humidity fall in near-entrance parts of caves, Culiseta females tend to stay in sites occupied earlier, while females of Culex migrate to neighbor sites with higher temperature and humidity.

Peculiarities of the pupal development of horseflies have been experimentally studied in Pskov Province with an example of tabanids. The temperature dependence of the pupal phase duration was investigated. Under stable laboratory conditions, the duration of pupal development of the same species obtained from larvae collected in the year of the investigation was characterized by strong fluctuations. Pupae obtained from larvae that had wintered in laboratory, had demonstrated the minimal degree of fluctuation concerning duration of the development. Reasons of these differences are discussed.

The fine structure of the metacestode Aploparaksis shigini Bondarenko et Kontrimavichus, 2006 from the predatory leeches Erpobdella octoculata L. from the lakes of the Upper Kolyma River basin was studied for the first time. The cysticercoid is similar to the floricercus, i.e. has an open cellular exocyst and many processes at its base, however, it is distinguished by a long tail. The exocyst and all its outgrowths (including the caudal process) are covered with long and thick microvilli. Excretory canals of different diameter are noted in the exocyst, near the base of the caudal process. The structure of the endocyst is typical of hymenolepidid metacestodes; the glycocalyx has a characteristic reticular structure.

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