[Ecology and epizootology of Microsporidia in malarial mosquitoes (diptera: culicidae) from the south of Western Siberia].

The ecology and epizootology of Microsporidia were studied in the natural population of malarial mosquitoes from Western Siberia over a 30-year period. Symptoms of the disease, host specificity and character of parasite localization in host tissues were investigated. Microsporidia of 9 species from 4 genera, namely Amblyospora, Crepidulospora, Senoma, and Parathelohania, were found in the malarial mosquito larvae from the territory examined. The mosquito species Anopheles messeae was infested by larger number of the microsporidian species, than A. beklemishevi. Spores and active stages of the microsporidian Senoma sp. from mosquito larvae are localized in epithelial cells of the host's intestine. There are no external signs of the infestation. The infested larvae do not die, and the infection proceeds to the pupal stage. Microsporidians of the genus Parathelohania infest larvae of both male and female mosquitoes. The parasites localized in the fat body cells. Body of the infested host gets an opaque white color in the period of spore maturation. The infested larvae perish at 4th stage. Microsporidian spores are formed in the mosquito larvae of both sexes. However, infection rate is much higher in the male larvae (77.8%), than that in the female larvae (22.2%). Symptoms of the disease under the infestation by the genera Crepidulospora and Amblyospora are similar to those under the infestation by Parathelohania sp. There are no external signs of the infestation in the adult mosquito females. In these hosts microsporidians form large two-nuclear spores with a thin capsule accounted for transovarial transmission. An about two times decrease of fertility in the Anopheles messeae females infested by the Parathelohania microsporidians is revealed. Mean number of eggs laid by the infested females was 121, while that of the noninfested ones was 232. Thus, the cause of the decrease in the mosquito abundance is both the elimination of male larvae and the decrease of fertility in females. In Siberia malarial mosquitoes yield 2 or 3 generations per year. Infested larvae are rarely occurred in the beginning of summer. Maximal extensiveness of the invasion may be observed in the end of summer, because of the accumulation of the infection in water bodies. Number of the peaks of infestation coincides with the peaks of abundance of mosquito larvae of 4th stage. Peaks of infestation are delayed as compared with the peaks of mosquito abundance. It is an evidence of the development delay in the infested larvae. Long-term dynamics of the infestation by microsporidians is studied. The epizooty caused by Parathelohania was observed in the malarial mosquitoes in the eighties (with the infestation rate up to 62 %). In the last ten years the infestation rate was low (from 0.1 to 2.6%).

[Six new species of microsporidia of the genus Amblyospora (Microspora: Amblyosporidae) from blood sucking mosquitoes (Diptera: Culicidae) from the west Siberia].

Microsporidia of the genus Amblyospora parasiting the adipose body of mosquito larvae of the genus Aedes and Culex has been studied with both light and electron microscopy. Six new species of microsporidia are described based on ultrastructural characteristics of spores and sporogony stages. Amblyospora flavescens sp. n. Mature spores are egg-shaped. The spore wall with three layers, about 165 nm. Exospore is two-membranous. Subexospore is absent. Endospore is electron-translucent. Polaroplast consists of three parts: lamellar, large vesicular, lamellar. The anisofilar polar filament with 10--11 coils (3 1/2 + 2 1/2 + 4-5). Fixed spores are 6.3 +/- 0.1 x 4.24 +/- 0.1 microm. Amblyospora kolarovi sp. n. Mature spores are egg-shaped. The spore wall with three layers, about 265-315 nm. Exospore shapes tucks on the surface of spore. It is two-membranous. Subexospore is quagge, structural. Endospore is electron-translucent. Polaroplast consists of two parts: lamellar and large vesicular. The anisofilar polar filament with 11-13 coils (3 + 8-10). Fixed spores are 5.4-5.6 x 3.5-4.2 microm. Amblyospora orbiculata sp. n. Mature spores are widely egg-shaped. On a back pole there is a small concavity. The spore wall with three layers, about 155 nm. Exospore is shapes tucks on a surface of spore. It is two-membranous. Subexospore is absent. Endospore is electron-translucent. Polaroplast consists of three parts: lamellar, vesicular, lamellar. Polar filament is anisofilar, with 11 1/2 coils (4 1/2 + 1 + 6). Fixed spores are 6.3 +/- 0.1 x x 4.0 +/- 0.1 microm. Amblyospora rugosa sp. n. Mature spores are egg-shaped. On a back pole there is a small concavity. The spore wall with three layers, about 225 nm. Exospore is shapes tucks on a surface of spore. It is two-membranous. Subexospore is quaggy, structural. Endospore is electron-translucent. Polaroplast lamellate. Polar filament is anisofilar, with 17 1/2 coils (3 1/2 + 1 + 13). Fixed spores are 5.3 +/- 0.1 x 3.7 +/- 0.1 microm. Amblyospora undata sp. n. Mature spores are egg-shaped. The spore wall is three-layered, about 220 nm. Exospore is shapes tucks on a surface of spore. It is two-membranous. Subexospore is quaggy, structural. Endospore is electron-translucent. Polaroplast lamellate. The anisofilar polar filament with 8 coils (3 + 5). Fixed spores are 5.0 +/- 0.1 x 3.0 +/- 0.1 microm. Amblyospora urski sp. n. Mature spores have widely oval form. The back pole is concave. The spore wall with three layers, about 280 nm. Exospore is shapes tucks on a surface of spore. It is two-membranous. Subexospore is quaggy, structural. Endospore is electron-translucent. Polaroplast lamellate. Polar filament is anisofilar, with 6 coils (2 + 4). Fixed spores are 4.4 +/- 0.1 x 2.9 +/- 0.1 microm.

[Crepidulospora--nomen novum for the junior generic homonym (preoccupied generic name) Crepidula]. / Crepidulospora--novoe nazvanie dlia mladshego gomonima, (preokkupirovannogo rodovogo imeni) Crepidula.

Crepidulospora nom. nov. is a replacement generic name for the genus Crepidula Simakova, Pankova et Issi, 2003 based on the type species Crepidula beklemishevi Simakova, Pankova et Issi, 2003 (Microsporida) from Anopheles beklemishevi. The name proposed by Simakova et al., 2003 is a preoccupied name, because it was already used for the gastropode Crepidula Lamarque 1899 (Echinospirida, Calibraeidae), a parasite of Mytilus. A valid name of the type species of the genus is now Crepidulospora beklemishevi (Simakova, Pankova, Issi, 2003) comb. n. Crepidulospora Simakova, Pankova et Issi nom. non. Type species: Crepidula beklemishevi Simakova, Pankova, Issi, 2003. Diagnosis. Sporogony is octosporoblastic. Sporogonal stages are in direct contact with host cell cytoplasm. 8 uninucleate spores, 4.2 x 2.2 mkm, are sandals-like. Polar tube is anisofilar, with 6-7 coils (2 + 4-5). Polaroplast is three-partite, with broad vesicular, vesicular and lamellar compartments. Microsporidia ilnfects larval adipose tissues. Type host: Anopheles beklemishevi (Diptera, Culicidae).

[Microsporidia of the genus Parahtelohania (Microspora: Amblyosporidae) from blood-sucking mosquitoes of the genus Anopeles (Diptera: Culicidae) from the South of the West Siberia]. / Mikrosporidii roda Parathelohania (Microspora: Amblyosporidae) iz komarov roda Anopheles (Diptera: Culicidae) iuga Zapadnoi Sibiri.

Five new microsporidian species of the genus Parathelohania have been found in the fat body of blood-sucking mosquitoes collected in various water basins in the South of West Siberia: Parathelohania divulgata sp. n., P. formosa sp. n., P. sibirika sp. n., P. teguldeti sp. n., and P. tomski sp. n. Processes of merogony, sporogony, and ultrastructure of spores was were investigated by means light and electronic microscopy.

[Crepidula beklemishevi gen. et sp. n. and Dimeiospora palustris gen. et sp. n. (Microspora: Amblyosporidae)--new microsporidian genera and species from blood-sucking mosquitoes (Diptera: Culicidae) from the south of the western Siberia]. / Crepidula beklemishevi gen. et sp. n. i Dimeiospora palustris gen et sp. n. (Microspora: Amblyosporidae)--novye mikrosporidii iz krovososushchikh komarov (Diptera: Culicidae) iuga zapadnoi Sibiri.

Microsporidia parasitizing the adipose body of mosquito larvae of Anopheles beklemishevi and Aedes punctor has been studied. Two new genera of microsporidia are described based on lightmicroscopic and ultrastructural characteristics of spores and sporogony stages. The spore wall of Crepidula beklemishevi gen. n. et sp. n. is formed by two-membrane exospore, thick exospore, bilayer endospore and thin plasmolemma. Spores with single nucleus, polar filament anisofilar, with 6-7 coils (2+ 4-5), polaroplast consisting of three parts: macrochelicoidal, microhelicoidal and lamellar. Fixed spores 4.2 +/- 0.22 x 2 +/- 0.01 microns. The sporogony of Dimeiospora palustris gen. et. n. results in spore formation of two different types. Spores of the first type are oviform, with thick wall, single-nuclear, 6.1 x 4.9 microns. Spore wall with three layers, about 370 nm. Exospore electron-dense, subexospore moderately electrondense. Exospore and subexospore irregularly pleated on the almost spore surface and slightly thinner on anterior end only. Endospore electron-translucent. Polar filament anisofilar, with 9 coils (3 + 6). Polaroplas consists of three parts: lamellar, fine bubbled, and coarse bubbled. Spores of the second type broad-ovate, with apical pole narrower, distal pole concave, 4.6 x 3.7 microns. Spore wall with three layer, 355 nm. Exospore on the apical end irregularly pleated, consists of thin electrondense exospore, subexospore of variable electron density, endospore electron-translucent. Polar filament anisofilar, with 13 coils (3 + 10). Polaroplast has two parts: lamellar and vesicular.

[Refinement of the diagnosis of Issia globifera (Microsporidia: nosematidae) based on ultrastructural data]. / Utochnenie diagnoza Issia globulifera (Microsporidea, nosematidae) na osnove dannykh po ul'trastrukture mikrosporidii.

An ultrastructure of a microsporidian belonging to the aberrant and poorly studied genus Issia is discribed in this paper. The first description of Issia globulifera (Issi, Pankova, 1983) was made on the basis of light microscopic analysis of midgut smears of the infected insects. Both late merogonic and sporogonic stages can be met on the sections from midguts of Anopheles messae. Meronts are ameba-like cells (3.0-3.5 x 2.0-2.5 microns) forming conglomerates of cells without any regular organization. Meronts and sporonts directly contact with the host cell cytoplasm; they are surrounded by numerous mitochondria. Sporonts divide into 2 sporoblasts, but remain connected with each other by posterial ends. In the vicinity of the contact the paramural bodies (structures, presumably participating in the formation of the exospore) can be seen. Sporoblast morphogenesis is accompanied by the rapid grow of electron dense layer in the region of the contact of two sister sporoblasts. Due to such intensive growth the sporoblasts are finally located at sharp angle to each other. Envelopes of sporonts and sporoblasts possess typical 2-membrane structure. Their nuclei lay in pairs like in Nosema species. Sporoblasts (unlike meronts and sporonts) are surrounded by the electron lucid zone of the cytoplasm with numerous tubule-like and spherical inclusions. Host mitochondria are closely adjacent to the periphery of this zone. The formation of characteristic spherical structures (globules), in which the posterior ends of two (in rare cases of 1 or 4) sister spores are downsinked, starts immediately after the sporont division. Globules rapidly increase in size during the sporogenesis. The homogenous globule (6-8 microns), which is essentially larger than a spore, seems to represent the modified exospore; it is not limited by any visible membrane. Fine structure of spores (2.5-3.0 x 2.0-2.3 microns) is typical for the nosems: spherical polar disk; lamellas polaroplast; nuclei located along the long spore axis; basal part of a polar tube forming a fork. A thin (25-40 nm) heterophilar polar filament forms 12 rows of various structure (8 + 4) packed in two rows. The posterior vacuole was no revealed. Endospore is very thick up to 250-400 nm in mature spores. The exospore covering the 2/3-4/5 of the spore length passes into the globule on the posterior end. The refined diagnosis of Issia globulifera: type host species--Anopheles messae (larvae, pupae); tissue localization: mitgut epithelium; terra typica: Siberia, Tomsk region, Ob river basin; developmental stages: multicellular merogonial plasmodium, sporont gives rise to 2 (rarely 1 or 4) sporoblasts connected with each other by a "globule", a specific formation homologous to an exospore of other microsporidians; globule (6-8 microns) possesses a homogenous inner structure of average electron density; sporophorous vesicle not formed; spore structure is typical for Nosematidae. Embeddings, negatives (## 2301, 2303, 2308, 2311-2313, 2532, 2533) and photos of type material in the collection of All-Russian Institute for Plant Protection.

[New species of Microsporidia in the genus Amblyospora from blood-sucking mosquitoes in the family Culicidae]. / Novye vidy mikrosporidii roda Amblyospora iz krovososushchikh komarov semeistva Culicidae.

Two microsporidians of the genus Amblyospora from mosquito larvae of Aedes and Culex were studied in Tomsk region (Siberia). Peculiarities of the sporogony and the meiospore ultrastructure were studied by light and electron microscopy. The meiospores of A. caspius sp. n. from Aedes caspius and Ae. communis measured on smears, were c. 4.8 x 3.6 microns in size. A polar filament was anisofilar with 5 wide (290 nm) and 9 narrow (190 nm) coils arranged in a single layer. A polaroplast of both species was composed of two parts: anterior lamellae and posterior fibrillae. Meiospores of A. burlaki sp. n. from Culex pipiens measured c. 4.8 x 3.5 microns. A polar filament was anisofilar with 3 wide (260 nm) and 6 narrow (110 nm) coils. The meiospore of this species had a 260 nm thick multilayered exospore.

[Distribution of natural parasites--fungi and microsporidia--in a population of malarial mosquito larva (Diptera: Culicidae) before and after infection by the entomopathogenic bacteria Bacillus thuringiensis israelensis]. / Raspredelenie estestvennykh parazitov--gribov i mikrosporidii--v populiatsii lichinok maliariinykh komarov (Diptera: Culicidae) do i posle infitsirovaniia éntomopatogennoi bakteriei Bacillus thuringiensis israelensis.

The distribution specificity of fungi and microsporidies in natural population of Anopheles messeae Fall. and A. beklemishevi Stegny et Kab. and those which survived after treatment them by Bacillus thuringiensis israelensis (Bti) were observed. Parasitic fungus nonselectively affected individuals of both species and all inversion genotypes of A. messeae. Microsporidia Parathelohania messeae affected males and it has not species and genotypic specificity. The 4-th instar larvae of both species infected by parasitic fungus after treatment them by Bti did not survive. The level of microsporidian infection of A. messeae and A. beklemishevi after Bti treatment was reduced from 1.1 +/- 0.5 to 0.5 +/- 0.3% and from 1.3 +/- 1.3 to 0.7 +/- 0.5% accordingly. A. beklemishevi was registered as Parathelohania messeae host for the first time. The harmonious relationships between malaria mosquitoes and their parasites in natural populations may be destructed by the Bti treatments.

[Experimental study of the routes of transmission of Microsporidia in blood-sucking mosquitoes from southwestern Siberia]. / Eksperimental'noe izuchenie putei peredachi mikrosporidii krovososushchikh komarov iuga Zapadnoi Sibiri.

Experiments were conducted on the artificial infection of larvae of 8 species of bloodsucking mosquitoes (Aedes diantaeus, A. punctor, A. cinereus, A. flavescens, A. aegypti, Culex pipiens, Anopheles messeae, Anopheles atroparvus) with spores of Amblyospora opacita var. sibirica, Parathelohania costatus sp. n., P. obesa, P. anophelis. Negative results were obtained in all experiments.

[New species of microsporidian Issia globulifera sp. n. (Nosematidae) in the malarial mosquito Anopheles maculipennis]. / Novyi vid mikrosporidii Issia globulifera sp. n. (Nosematidae) maliariinogo komara Anopheles maculipennis.

A microsporidia, Issia globulifera sp. n., which has diplocaryotic stages during its whole developmental cycle and disporoblastic sporogony, is described. Spores are eggshaped, 3.6 X 2.4 mu in size. During sporogenesis at the hind pole of spores in the place of their contact a globule holding spores together is formed. Spores and globule are covered by a compact pansporoblastic membrane.