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The salivary glands of the representatives of the subfamilies Ixodinae and Amblyomminae are significantly different in their structure and functions. These organs are formed of alveoli of 4 types. The alveoli of I type only are similar in structure in both subfamilies, because they provide the vapour absorbtion in hungry ticks. The cell number, ultrastructure and chemical compound of secretory inclusions as well as functional activity of alveoli of II, III, and IV types are significantly different. The similarity is observed only in cells «f» of III type, which provide the removal out an excess amount of water and salts. Granular-secretory cells are quite different in their structure and secret production. The designation the secretory cells of all ixodid ticks as "а", "b", "с", and others is rather conventional, and the homology of them in Ixodinae and Amblyomminae needs additional studies. Difference in chemical compound of saliva and intensivity of its production in different period of feeding influences the direction and protective reactions of host organism.

Fine structural investigation of specialized seta on body limbs of larvae and adult chiggers (12 species) had made it possible to distinguish among them olfactory sensilla (solenidia), gustatory sensilla (eupatidia) and thermo-hygroreceptors (famuli). Problems of evolutionary development of sensory apparatus in chiggers during adaptation to larval parasitism and post-larval predation is discussed.

The dependence of the species composition and abundance of biting midges upon a degree of the antropogene impact in landscape of the vicinity of St. Petersburg was investigated. The species of the subgenus Monoculicoides could be used as bioindicators of the environmental pollution.

Different methods of estimation the elimination potential of invertebrate hydrobionts, members of water biocenoses, in relation to freeliving instars such as egg (miracidium) and cercarium of O. felineus are considered. Calculations and conclusions are based on field and laboratory investigation carried out in the period 1985—1992. The elimination process in biocenoses does not practically influence on the intensivity of infection, but influences significantly on the extensivity of the infection of the molluscs Codiella with O. felineus larvae. This process is also the cause of low extensivity of enfection of Codiella in natural water reservoirs (usually less 1—2.5%) in all infection centres of exUSSR area including Western Siberia. The eggs (miracidia) of O. felineus are eliminated with different effectivity by invertebrate of nectobentos (oligichaeta, molluscs, and with less rate by arthropodes). Coracidia are eliminate generally by nectoplancton crustaceans and water insect larvae. Invertebrate hydrobionts eliminate about 70% cercaria of the number coming out the infected molluscs being intermedial hosts.

The study has been carried out on Blastocystis galli Belova et Kostenko, 1990. The characters as the presence of glycocalex, plasmatic membrane, ameboid and plasmodial organisation of the cell, pseudopodia of lobopodial type, tube christs of mitochondria, reservoirs of the Goldgi apparatus arranged in a pile, point out the belonging of B. galli to the reign Protista, type Rhizopoda, class Lobosea, subclass Gimnamoeba. It is proposed to rise up the taxonomy rank of the suborder Blastocystina Zierdt, 1988 to the order rank.

Description of Haemoproteus payevskyi sp. n. parasitizing in reed warbler is presented. The new species has small gametocytes which never fill the poles of infected erythrocytes. The nucleus is located centrally in macrogaraetocytes. The pigment granules show a clear tendency to be clumped at the poles of macrogametocytes. The nucleus of microgametocytes is relatively small and compact. The dimension of the nucleus of microgametocytes do not exceed the dimension of the nucleus of macrogametocytes. The new species is compared with H. belopolskyi, H. sylvae, H. wenyoni and other related species of passerine haemoproteids.

The history of descriptions of the reproductive system of diplozoids is displayed. Different authors referred the canal through which the spermatozoa pass into the second worm (spermcarring duct) as vagina, vas deferens of another worm, ductus vaginalis, ductus vaginoides de novo. In order to understand the nature of the spermcarrng duct of diplozoids, the author used the collection of Zoological Institute of Russian Academy of Sciences for checking the structure of reproductive system of key species, original descriptions of which were put into the base of different points of view on the nature of the diplozoids spermcarring duct. We confirm the description of the structure of the reproductive system Eudiplozoon nipponicum (Goto, 1891), in which the spermcarring duct considered as vas deferens of another worm, and improve the picture of the reproductive system Paradiplozoon zeller (Gyntovt, 1964) displayed by Zeller (1888) by the description of genito-intestinal canal. Critical re-estimation of data of Bovet (1967) for the reproductive system structure of "Diplozoon paradoxum" and of the same description given by Khotenovsky (1985) is proposed. Distinctly different morphogenesis of reproductive system of Eudiplozoon nipponicum and Diplozoon paradoxum is described. In latter species the morphogenesis has a resemblance with one of Paradiplozoon rutili (after: Gerasev, Khotenovsky, 1985). In representatives of the genera Diplozoon and Paradiplozoon the spermcarring duct is formed in the specimen, which assumed spermatozoa, and it may fall into the oviduct or vitelline resevoir. In our opinion, in this case the spermcarring duct is the ductus vaginoides de novo. In the genera Eudiplozoon, Inusiatus and Sindiplozoon we consider the spermcarring duct (according Goto and others) as vas deferens of second worm, that falls into vitelline duct.

A new species of microsporidia has been described from the laboratory population of Gryllus bimaculatus using light and electron microscopy. All stages of parasite life cycle have been examined. Characteristic features (nuclei in diplokariotic arrangement, direct contact of all developmental stages with host cell cytoplasm, disporoblastic type of development, ultrastructural details of the spore extrusion apparatus) indicate on the position of the species studied inside the genus Nosema. Large number (18—20) of polar filament coils arranged in two layers, intensive secretory activity on prespore stages in combination with some other features differ Nosema grylli from other nosems. This microsporidia is the first one discovered in crickets (Gryllidae). Comparative review of microsporidia species infective for Orthoptera is given.

Invasion activity of different geographical populations of nematodes some genera of Steinernematidae and Heterorhabditidae against currant clearing moth, Synanthedon tipuliformis, and locust, Chortippus albomarginatus at 10°C to 30°C has been studied. The most active invasion into host insect by nematode population Steinernema sp. 90 from Yakutia was observed at optimum temperature limits from 18 to 21°C while the most high activity of S. carpocapsae — strain "agriotos" was observed from 23 to 27.5°C. The highest activity of other nematode strains and species was observed at 20°C.

The ultrastructure of genital ducts of feminine and musculine genital system and copulatory organ of monozoic cestode Caryophyllaeus laticeps has been examined. Difference in structure, functional peculiarities and origin of different parts of genital apparatus are discussed.

The authors propose a model of extractor using sun light for the extraction the dwellers of burrows and nests of rodents in field circumstances.

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