Inversion polymorphism in malaria mosquito Anopheles messeae. Part X. Resistance of larvae with different genotypes to toxins of crystal-forming bacteria Bacillus thuringiensis subsp. israelensis (serovar H14)

Insensibility of larvae with different chromosomal inversions to the toxins of Bacillus thuringiensis subsp. israelensis (Bti) was examined. It has been shown that larvae with inversion combinations XL0(XL1)2R0-3R0-3L0 had greater variability after treatment with Bti than larvae with inversions XL1(XL2)2R1-3R1-3L1(3L0). The former inversion combinations were previously shown to dominate in the south of the species area and to be supported by K-selection. The latter inversion combinations form "northest" karyotypes and are supported by r-selection. It is obvious that genetic effects of treatments with Bti depend on the population's structure and the directions of natural selection. The decrease in the level of heterozygotes after treatment of larvae with Bti reflects destruction of the system of genetic homeostasis in the natural populations of A. messeae.     

Genetic distance of the malarial mosquitoes, Anopheles beklemishevi and Anopheles messeae (Diptera, Culiccidae), and their intraspecific polymorphism

Allele frequencies at enzyme loci have been studied in Finnish populations of two species of the Anopheles maculipennis complex: A. beklemishevi and A. messeae. A. beklemishevi is spread over central and northern Finland, whereas A. messeae is found in southwestern and central Finland. The allele frequencies of these two species exhibit both similarities and differences. The results indicate that the two species do not interbreed in the nature. The allele frequencies at two loci--Hydroxybutyrate dehydrogenase (Hbdh) and Superoxide dismutase-2 (Su-2)--are almost totally different and adult individuals of the two species can be reliably diagnosed by these allelic differences. The genetic distance, D, between A. beklemishevi and A. messeae is 0.35. This value is compared with corresponding distances between other dipterans studied.     

Chromosomal polymorphism in the populations of malaria mosquito <Emphasis Type="Italic">Anopheles messeae</Emphasis> (Diptera,Culicidae) in the Volga region

We studied the species composition and chromosomal variability of malaria mosquitoes in the Volga Basin (Upper, Middle, and Lower Volga regions). We investigated larvae karyotypes of sibling species of the Anopheles maculipennis group. We calculated the frequencies of chromosomal inversions in the local populations of the dominant species An. messeae. We discovered that karyotypic structure of An. messeae populations depends on landscape-climatic zones. Populations of the Upper, Middle and Lower Volga differ in frequency of chromosome inversions XL, 2R, 3R, and 3L.     

Inversion polymorphism in malarial mosquito Anopheles messeae natural populations from the north-eastern region of the range

A cytogenetic study of eight natural populations of Anopheles messeae from the north-eastern part of the species areal was conducted. Complete predominance of homozygotes XL11 and 3R11 in the northern populations was observed. Change in the chromosome 2 inversion frequencies from south northwards was shown. The 2R11 variant, which was not observed in the southern region, was found in the northern populations. These results indicate the maintenance of chromosome frequency of the distribution of inversions XL1 and 3R (in longitude) and 2R1 (in latitude). The inversion frequency distribution in the examined part of the areal have been preserved for a long time.     

Inversion polymorphism in the malaria mosquito Anopheles messeae. VI. Local selection and 3-dimensional differentiation of the inversion gene complexes for fertility

A field experiment was carried on with the view of compulsory change of the frequency of chromosomal inversion (2R1) in the population of Anopheles messeae from the centre of the area. Quick return of the population to the original structure was observed. This confirmed that the local differentiation of chromosomal polymorphism is supported by natural selection. The fertility of the females was shown to be connected with the inversion polymorphism. The females with inversion complexes of genes of the "northern" type (with homozygotes 2R1) had higher fertility and lower dispersion of the fertility, in comparison with those having gene complexes which prevailed in the south part of the area.     

Cytogenetic analysis of the species composition and inversion structure of populations of malarial mosquitoes in the Astrakhan region

A cytogenetic analysis of Anopheles mosquitoes in the Astrakhan region was carried out. Three species of Anopheles were identified. An. messeae lives everywhere and prevails in all of the areas of research, An. hyrcanus is found in the southwest of the region, and An. maculipennis in the northern part of the region. The populations of An. messeae show a high level of inversion polymorphism for the sex chromosome and the third autosome. A clear clinal trend of an increase in chromosomal rearrangements XL1, 3R1, and 3L1 and a decrease in the frequency of evolutionary source alternatives was revealed in laraval hemipopulations of the species from south to north.     

Characterization and comparative analysis of DNA from the pericentric heterochromatin of chromosome 2 of Anopheles atroparvus V. Tiel (Culicidae, Diptera)

The minilibrary containing DNA sequences from the diffuse pericentric heterochromatin from the right arm of Anopheles atroparvus V. Tiel (Culicidae, Diptera) chromosome 2 (2R) was generated by use of chromosome microdissection technique. Southern-blot hybridization of the minilibrary fragments with the labeled genomic DNA of A. atroparvus and analysis of their primary structure showed that this heterochromatin region contained repeated DNA sequences differed by their primary structure and the number of copies. These were mostly AT-rich sequences harboring the features characteristic of the S/MAR regions. Based on the clones homology to the sequences from the An. gambiae and Drosophila melanogaster genomes, it was demonstrated that the pericentric heterochromatin from the right arm of An. atroparvus chromosome 2 contained gypsy-like transposable elements, as well as the sequences homologous to the structural genes. In situ hybridization with the chromosomes of A. atroparvus and of the two representatives of the Anopheles maculipennis species complex, A. messeae and A. beklemishevi, showed that pericentric regions of all these chromosomes contained DNA sequences homologous to the sequences from the region-specific minilibrary. Cloned fragments of conserved repetitive DNA revealed upon interspecific Southern-blot hybridization of the clones with the labeled genomic DNA of A. messeae can be utilized in further investigations of evolutionary rearrangements of the pericentric heterochromatin within the Anopheles maculipennis species complex.     

On ranges of the malaria mosquitoes (Diptera: Culicidae: Anopheles) of the Maculipennis complex on the territory of Russia

Maps and distribution data are provided for the seven mosquito species of the genus Anopheles, the maculipennis group: Anopheles atroparvus, A. beklemishevi, A. maculipennis, A. messeae, A. malanoon, A. sacharovi and A. subalpinus.     

Adaptive association of inversions in a natural population of the malaria mosquito Anopheles messeae Fall.]

The dependent combination of chromosomal variants by five paracentric inversions (IL1, IL2, IIR1, IIIR1, IIIL1) in Anopheles messeae population from the West Siberia was discovered. It is found that the inversion interactions interactions are the same at both larval and imaginal parts of the population, and they are stable during four years of studying. The inversion of hetero- and homozygotes demonstrates identical properties, that is, phylogenetic secondary sequencies dominate in heterozygotes. Two associative groups of chromosome variants were revealed. The association correlates with geographic distribution and temporal dynamics of inversions and on the whole, it reflects the evolutionary history of inversion polymorphism in A. messeae. It is supposed that the adaptive association of inversions found is the high degree polymorphism formed and functioned on the basis of the groups of inversion chromosome blocks.     

Inversion polymorphism in the malaria mosquito Anopheles messeae. VII. Fertility and the population genetics structure of the species

The role of chromosomal inversional complexes of different fecundity has been studied in the process of formation of karyotypic populational structure. Females with homozygotes 2R11 and "north-est" inversional combinations are shown to have maximal total egg production, while females with three or four inversional heterozygotes from XL01, XL12, 2R01, 3R01 and 3L01 demonstrated lower level of fecundity. It is found that the seasonal conversion from r-selection to K-selection occurs in the period of population "prosperity" (July). The results of such conversion are destruction of "northest" genocomplexes and reduction of relative fecundity of inversional homozygotes 2R11-Alternative tendencies take place at the beginning of the reproductive period.     

Mosquitoes of the Anopheles maculipennis group (Diptera: Culicidae) in Romania, with the discovery and formal recognition of a new species based on molecular and morphological evidence

Mosquitoes of the Anopheles maculipennis group were collected in five districts of Romania (Constant,a, Giurgiu, Ilfov, Mehedint,i and Suceava) between March 2000 and June 2003. Two hundred and ninety-seven specimens were identified by molecular methods. Nuclear rDNA ITS2 sequences of 178 specimens were compared with GenBank sequences for nine known Palaearctic species of the group, and 119 specimens were identified using an ITS2 PCR-RFLP assay developed during the study. Five genetically distinct species of the group were identified: A. atroparvus van Thiel, A. maculipennis Meigen, A. melanoon Hackett and A. messeae Falleroni and a previously unrecognized species. The new species, herein formally described and named A. daciae sp. n., was collected in the Black Sea coastal region and plains adjacent to the Danube River in southern Romania. Anopheles daciae is most similar to and sympatric with A. messeae. It is contrasted with A. messeae and characterized on the basis of unique nuclear ITS2 and mitochondrial COI DNA sequences and morphological characters of the eggs. The larval, pupal and adults stages of the two species were also compared, but no reliable characters were found to distinguish them. It seems likely that A. daciae is more widespread in eastern Europe and the Balkan States, and could be responsible for malaria transmission in these regions that is currently attributed to A. messeae. Anopheles melanoon is reported from Romania for the first time.     

Inversion polymorphism in the malaria mosquito Anopheles messeae. XI. The group effect of larval infection with Bacillus thuringiensis subsp. israeliensis bacteria]

Genetic consequences of the group and individual infections of Anopheles messeae larvae with bacteria Bacillus thuringiensis subsp. israelensis (Bti) were examined. The group effect of infections was manifested by increase in mortality and the speed-up of selection of chromosomal inversions resistant to Bti. Connection between the group and individual selections during the process of populations' adaptation is under discussion.     

Inversion polymorphism of the malarial mosquito Anopheles messeae. V. The interaction of different chromosomal inversions in the spatial area

The relations between inversions of chromosome XL, 2R, 3R, 3L from 8 populations of the central part and periphery of the species area were studied. 2-, 3- and 4-factor analysis was carried out. Interaction of inversions XL1, 2R1, 3R1 in central populations (Riga, Moscow, Tomsk) was observed. The nonrandom association of definite inversional genotypes was stationary in spatial - temporary. The phylogenetic initial sequences XL0, 2R0, 3R0 display "+" interaction. The 3-factor analysis of populations of Tomsk shows: 1) interaction of inversions is more essential in males than in females; 2) the statistically significant interaction of 3-4 inversions is not always determined by the effect of 2-factor analysis; 3) the chromosome 3R has a dominance influence on the pattern of association of the multiinversional complex. These data support the hypothesis that differential selection for chromosomes with certain combinations of arrangements is mainly responsible for this phenomenon. In peripheral area populations (Syctyvkar, Irkutsk, Chita), no associations were observed (2R and 3R). When they do take place, their character is changed (Kiev - XL and 3R). This phenomenon may be explained by the influence of frequency-dependent selection.     

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%).     

Localization of repetitive DNA sequences in the pericentromeric heterochromatin of malarial mosquitoes of the "Anopheles maculipennis" complex

Distribution of eight fragments of conserved repetitive DNA from pericentromeric heterochromatin of chromosome 2 of Anopheles atroparvus has been investigated by in situ hybridization on polytene chromosomes of An. atroparvus and An. messeae. We have shown that heterochromatic regions of all chromosomes both in An. atroparvus and An. messeae vary in combinations of, at least, conserved repeats. Some repeats have been found only in pericentromeric heterochromatic regions of chromosomes 2 (clones Atr2R-46a, Atr2R-73, Atr2R-85a in An. atroparvus and Atr2R-25 in An. messeae). Others have been found in two (clones Atr2R-25a and Atr2R-90 in An. atroparvus, Atr2R-25a in An. messeae) and more (clones Atr2R-118, Atr2R-136 in An. atroparvus, Atr2R-73 in An. messeae) pericentromeric heterochromatic regions of chromosomes. DNA comparison of pericentromeric heterochromatic regions of chromosomes in species of the "Anopheles maculipennis" complex is species- and chromosome-specific, due, in particular, to different maintenance of conserved repeates.     

Inversion polymorphism of the malarial mosquito Anopheles messeae. IV. The stability of the frequency distribution of the inversions by species area

Distribution of the frequencies of inversions XL1, 2R1, 3R1, 3L1, from geographically widely separated 8 populations had been studied during a long period of time. The geographical inclines of distribution of inversions XL1, 3R1 (a longitudinal) and 2R1 (a latitudinal) are stable in time. Stationarity of inversional polymorphism is not connected with superdominance of heterozygotes. It is supposed that the stable equilibrium of the frequencies of inversions is supported by variable selection.     

Chromosomal and cross-mating evidence for two species within Anopheles (A.) coustani (Diptera: Culicidae)

Abstract Examination of the polytene chromosomes of the fourth instar larvae provides evidence for the existence of two sibling species within the taxon Anopheles (Anopheles) coustani Laveran. Crosses between the two chromosomal types produces sterile male offspring. Since no classical morphological differences can be demonstrated in the adults, the probable existence of such characters in the larvae and pupae is discussed.     

Morphological and chromosomal descriptions of new species in the Anopheles subpictus complex

Abstract. Anopheles subpictus Grassi is shown to comprise four reproductively distinct species, designated A, B, C and D, occurring sympatrically in villages of Pondicherry, southeast India.
Adult females were reared individually from wild larvae and examined for their morphological and chromosomal characters. Paracentric fixed inversions on the X-chromosome serve to distinguish the species cytogenetically, with no inversion heterozygotes (i.e. no interspecific hybrids) among totals of 717 species A (X+^a,+^b), 1863 species B (Xa, b), 869 species C (Xa,+^b) and 1365 species D (X +^a,b) identified.
Morphologically, diagnostic characters for each of the four species are seen in the egg float ridge number, larval mesothoracic seta 4, pupal seta 7-1 and the palpi of female adults. Species A. C and D immatures inhabit freshwater, whereas the malaria vector species B breeds in saltwater and was found only in coastal villages.     

Genetic differentiation in the African malaria vector, Anopheles gambiae s.s., and the problem of taxonomic status

Of the seven recognized species of the Anopheles gambiae complex, A. gambiae s.s. is the most widespread and most important vector of malaria. It is becoming clear that, in parts of West Africa, this nominal species is not a single panmictic unit. We found that the internal transcribed spacer (ITS) of the X-linked rDNA has two distinct sequences with three fixed nucleotide differences; we detected no heterozygotes at these three sites, even in areas of sympatry of the two ITS types. The intergenic spacer (IGS) of this region also displays two distinct sequences that are in almost complete linkage disequilibrium with the distinct ITS alleles. We have designated these two types as S/type I and M/type II. These rDNA types correspond at least partly to the previously recognized chromosomal forms. Here we expand the geographic range of sampling to 251 individuals from 38 populations. Outside of West Africa, a single rDNA type, S/type I, corresponds to the Savanna chromosomal form. In West Africa, both types are often found in a single local sample. To understand if these findings might be due to unusual behavior of the rDNA region, we sequenced the same region for 46 A. arabiensis, a sympatric sibling species. No such distinct discontinuity was observed for this species. Autosomal inversions in one chromosome arm (2R), an insecticide resistance gene on 2L, and this single X-linked region indicate at least two genetically differentiated subpopulations of A. gambiae. Yet, rather extensive studies of other regions of the genome have failed to reveal genetic discontinuity. Evidently, incomplete genetic isolation exists within this single nominal species.     

Crepidulospora--nomen novum for the junior generic homonym (preoccupied generic name) 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).