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A local population of any species of helminths is considered to be an assemblage of its individuals pressentas i the organisms of all categories of hosts from corresponding demes so in the environment within the limits of the latter. Its borders coinside with the limits of the activity zone of the definitive host (hosts) which contains a spreading phase of helminths, mature individuals, and is represented by a local population. The borders of the population area are affected by daily and seasonal fluctuations but at the same time rather constant within a long time. The number of the population in different parts of its area can be dissimilar. It is also characterized by many-year fluctuations (pulsation in the number) having a specific character for each species. It is supposed that control of helminths of a given population will be effective mainly in the period of natural recession and depression of its number. Birds-migrants do not cause great changes in the population number though the birds can play a significant part in the formation of new populations in new biotopes.

The division of the family Microcotylidae suggested by Unnithan, 1971 into subordinate taxons is quite unsatisfactory, A detailed analysis has shown that all the subfamilies erected by Unnithan due to some reasons or others are invalid. Of 13 new genera six are synonyms of other earlier known genera, one is nomen preoccupatum, one genus is doubtful and only five genera are valid. However, three genera of these five need a serious revision since they represent a conglomerate of non-allied species and one genus requires some emmendations.

On the basis of hystological studies a description of fission and gastrulation in Microsomacanthus paramicrosoma (Gasowska, 1931) is given. Eggs lacking morphological characters of polarity and symmetry display features of duet and spiral fission characteristic of lower groups of Turbellaria. Serial sections (5 mcm thick) have shown that the fission ends in the formation of coeloblastula consisting of 26±3 cells. Gastrulation is expressed in immigration into blastocoel of two micromeres which later degenerate. These micromeres are homologous to entomesodermal micromeres of other Platodes. Blastocoel disappears as a result of local reproduction of ectodermal cells that is regarded as an anlage of ectomesenchyma. Ectoderm and mesenchyma are not morphologically separated from each other.

A taxonomic status of a new species of Trichinella from Procyon lotor L. described by V.L. Garkavi in 1972 as T. pseudospiralis is discussed. Two-month invasional larvae resemble in their size and structure 19—20-day larvae of typical T. spiralis. However, the ratio between their organs points not only to the delay in development but also to significant structural morphological differences. Luminiscent microscopic analysis of muscular and intestinal forms of both species confirms this. Impossibility of crossing between both species is noted. Results of investigations show that T. pseudospiralis Garkavi can be accepted as a valid species.

Conducted experiments and observations in nature have shown that in spring and early summer the formation of egg sacs of Ergasilus sieboldi is stimulated only by temperature while from midsummer and in autumn it depends to a considerable extent on a day length. This suggests that parasitic crustaceans of the genus Ergasilus have a state of diapause.

Studies were carried out of the ultrafine structure of the midgut epithelium of hungry nymphs of O. papillipes. The intestinal epithelium has been shown to consist of both reserve and digestive cells which are at different stages of blood digestion. The former are characterized by a poor development of surface structures and by the absence of inclusions. On the contrary, the digestive cells abound in inclusions most of which are associated with intracellular blood digestion. On the surface of such cells there are specialized pinocytosis structures: coated kesicles and tubular invaginations. A number of cells possess vacuoles which are, apparently, secretory in their nature.

Described and figured are deutonymphs of 18 species of the genus Hirstionyssus Fonseca, 1948, parasites of small mammals (H. carnifex (L. C. Koch) Oudemans, 1913; H. blanchardi (Trouessart, 1904); H. ellobii Bregetova, 1956; H. myospalacis Zemskaja et Piontkovskaja, 1957; H. transiliensis Bregetova, 1956; H. georgicus Bregetova, 1956; H. sciurinus (Hirst, 1921); H. confucianus (Hirst, 1921); H. bregetovae Razumova, 1953; H. macedonicus (Hirst, 1921); H. pauli Willmann, 1952; H. criceti (Sulzer, 1774); H. latiscutatus (Meillon et Lavoipierre, 1944); H. apodemi Zuevsky, 1970; H. pavlovskii Zemskaja, 1959; H. soricis (Turk, 1945); H. meridianus Zemskaja, 1955; H. isabellinus Oudemans, 1913); Keys to deutonymphs of the genus Hirstionyssus are given for the first time.

524 nests of 12 species of birds were examined in the Volga—Kama state reserve. From these nests there were collected 214575 mites belonging to 11 families and 48 species. The specific composition and quantitative ration between ecological groups of gamasid mites associated with the nests of birds depend not only on the evolutionary history of the host and gamasids-nidicols but also on many present factors, ecological type of the nesting place in particular.

Fleas of Xenopsylla gerbilli and Xenopsylla hirtipes, parasites of Rhombonus opimus in the Kizil-Kum, have a sympathric distribution. Within a greater part of their common area both species vicariate in landscapes: X. hirtipes occupties more mesophilous parts while X. gerbilli is distributed in all parts where the first species is missing. The distribution of X. hirtipes depends first of all on abiotic environmental factors and that of X. gerbilli — on biotic ones, i. e. on the competition with X. hirtipes. However, under more favourable conditions (northern foothill valleys of the Bukantau ridge) both species occur together in great number.

The ability of apiosomes for the formation of non-contractile stems (such as epistylids) and colonies suggests to refer them to the family Epistylidae rather than to Scyphidiidae. On the other hand, the atrophy of the stem in the majority of the species, changes in the structure of the foot, in the form and position of the nuclei under the effect of parasitism on fishes suggest their separation into a distinct subfamily, Apiosomatinae subfam. n.

A method was worked out for cloning Leishmania strains at the promastigote stage from cultures reared on two-phase nutrient medium by means of Vonbrtin micromanipulator. By this method cultures of Leishmania can be obtained from one cell of these protozoans. During the cloning of Leishmania strains isolated from experimentally and naturally infected Phlebotomus papatasi and Ph. caucasicus the per cent of obtaining the clones from isolated promastigotes cultivated on a nutrient medium depends on the absolute and relative age of culture and on the growth intensity of the strain on a nutrient medium.

The fine structure of E. acervulina sporozoite excysted in vitro is described. It was found that quantitative characteristics of the ropthries-micronemes complex in sporozoite of this species is lower than that of other species. It is noteworthy that free sporozoite of E. acervulina has no amylopectin granules.

10 species of myxosporidians of teleost fishes from the northern part of Patagonian Shelf are described. Of them 9 species are described for the first time. They are members of the genera Zschokella, Sinuolinea, Myxoproteus, Ceratomyxa, Leptotheca and Myxobilatus. Conclusions are drawn concerning the origin of myxosporidians and the order of their appearance in the fishes of the shelf.

Experiments were conducted with ticks of I. persulcatus collected in the vicinity of Khabarovsk. The females were fed at the beginning of June, hatched larvae and nymphs — after the completion of postlarval development. The ticks were maintained in testglasses at constant humidity, at temperatures of 6, 12, 15, 28 and 33C in darkness. Minimum developmental periods of the ticks from egg to imago are 211 days at 28C, 732 days at 15C and 869 days at 12C. The development without diapause was not observed in the experiment.

The name Aedes (Finlaya) kobayashii Nakata, 1956 for the mosquitoes from Japan and South Korea is a synonym of A. (F.) alektorovi Stackelberg, 1943 from the south of the Soviet Far East as well as A. (F.) bunanoki Sasa et Ishimura, 1951 from Japan is a synonym of A. (F.) oreophilus Edwards, 1916 spread in Pakistan, India, China and related to Chinese-Himalayan subregion of the Palaearctic Region; therefore it may be spread also in Nepal, North Burma and in the south of the Soviet Far East. It is proposed to consider A. (Neomelaniconion) aureus Gutvsevich, 1955 from the Primorye Territory of the USSR as a subspecies of A. (N.) lineatopennis Ludlow, 1905 widely spread in the tropics of the Old World, i. e. A. (N.) lineatopennis aureus Gutsevich, 1955, stat. nov.

For maintenance of a laboratory culture of Aedes caspius caspius Pall. there was chosen a stenogamic autogene population from Bairam-Ali, Turkmenia (sandy desert zone). The conditions necessary for cultivation of the mosquitoes were revealed. 25generations were obtained for two years. Within this period biology of A. c. caspius was traced and evaluation of main biological indices of the culture given.

Lice occurring on small mammals of Priamurje are represented by six species. Of 6501 insects collected 91.2% fall on H. acanthopus. 99.8% of lice were collected from rodents of which the main hosts are Clethrionomys rufocanus and Microtus fortis. The active reproduction of insects takes place in a warm period. High abundance indices were registered from April to July: abundance indices were from 0.6 to 3.0; occurrence indices — from 10.1 to 24.9%.

IIIrd and IVth instar larvae of Aedes caspius and Uranotania unguiculata were found to be infected with Protozoa similar in their morphology with Tetrahymena stegomyiae. The infection extensity of A. caspius was 18 to 27% and that of U. unguiculata — 14 to 29%.

Summary is absent.