A comparative study on mouthpart morphology of certain larvae of Chironomini (Diptera: Chironomidae) with reference to the larval feeding habits

Mouthparts of six species of chironomid larvae were compared on both an intra- and inter-specific level. The species were: Chironomus riparius, Cryptochironomus defectus gr., Endochironomus albipennis, Glyptotendipes pallens, Microtendipes pedellus and Parachironomus arcuatus . The mouthpart morphology in C. defectus gr. and P. arcuatus is considerably different from the four other species and changes little between instars. Within C. riparius, E. albipennis, G. pallens and M. pedellus there is a considerable difference in the mouthpart morphology between the first instar and the remaining instars. The morphology of the mouthparts of the first instar of C. riparius, E. albipennis, G. pallens and M. pedellus resembles in many ways that found in C. defectus gr. and P. arcuatus .     

Evaluation of phylogenetic relationships between five polyploid Aegilops L. species of the U-genome cluster by means of chromosomal analysis

Four tetraploid (Aegilops ovata, Ae. biuncialis, Ae. columnaris, and Ae. triaristata) and one hexaploid (Ae. recta) species of the U-genome cluster were studied using C-banding technique. All species displayed broad C-banding polymorphism and high frequency of chromosomal rearrangements. Chromosomal rearrangements were represented by paracentric inversions and intragenomic and intergenomic translocations. We found that the processes of intraspecific divergence of Ae. ovata, Ae. biuncialis, and Ae. columnaris were probably associated with introgression of genetic material from other species. The results obtained confirmed that tetraploid species Ae. ovata and Ae. biuncialis occurred as a result of hybridization of a diploid Ae. umbellulata with Ae. comosa and Ae. heldreichii, respectively. The dissimilarity of the C-banding patterns of several chromosomes of these tetraploid species and their ancestral diploid forms indicated that chromosomal aberrations might have taken place during their speciation. Significant differences of karyotype structure, total amount and distribution of C-heterochromatin found between Ae. columnaris and Ae. triaristata, on the one hand, and Ae. ovata and Ae. biuncialis, on the other, evidenced in favor of different origin of these groups of species. In turn, similarity of the C-banding patterns of Ae. columnaris and Ae. triaristata chromosomes suggested that they were derived from a common ancestor. A diploid species Ae. umbellulata was the U-genome donor of Ae. columnaris and Ae. triaristata; however, the donor of the second genome of these species was not determined. We assumed that these tetraploid species occurred as a result of introgressive hybridization. Similarity of the C-banding patterns of chromosomes of Ae. recta and its parental species Ae. triaristata and Ae. uniaristata indicated that the formation of the hexaploid form was not associated with large modifications of the parental genomes.     

Polymorphism and divergence of multilocus DNA markers in sibling species Chironomus riparius Meigen and Chironomus piger Strenzke (Diptera, Chironomidae)

Intra- and interspecific variation and divergence of multilocus markers for genomic DNA of the sibling species from the thimmi group, Chironomus riparius and C. piger, were studied by PCR with arbitrary primers (RAPD). A high level of RAPD polymorphism was determined in both laboratory and natural populations of these species. The genetic distances were estimated between the C. riparius populations and between the sibling species C. riparius and C. piger. The genetic distance between C. riparius and C. piger was 4 to 5 times higher than that between the C. riparius populations. A comparison of the variation and divergence for the RAPD markers with those for other genomic markers--enzyme-coding genes and chromosomes (linked gene groups)--showed that different components of the genome differed in their contribution to the genome divergence.     

Evaluation of Phylogenetic Relationships between Five Polyploid Aegilops L. Species of the U-Genome Cluster by Means of Chromosome Analysis

Four tetraploid (Aegilops ovata, Ae. biuncialis, Ae. columnaris, and Ae. triaristata) and one hexaploid (Ae. recta) species of the U-genome cluster were studied using C-banding technique. All species displayed broad C-banding polymorphism and high frequency of chromosomal rearrangements. Chromosomal rearrangements were represented by paracentric inversions and intragenomic and intergenomic translocations. We found that the processes of intraspecific divergence of Ae. ovata, Ae. biuncialis,and Ae. columnaris were probably associated with introgression of genetic material from other species. The results obtained confirmed that tetraploid species Ae. ovata and Ae. biuncialis occurred as a result of hybridization of a diploidAe. umbellulata with Ae. comosa and Ae. heldreichii, respectively. The dissimilarity of the C-banding patterns of several chromosomes of these tetraploid species and their ancestral diploid forms indicated that chromosomal aberrations might have taken place during their speciation. Significant differences of karyotype structure, total amount and distribution of C-heterochromatin found between Ae. columnarisand Ae. triaristata, on the one hand, and Ae. ovata and Ae. biuncialis, on the other, evidenced in favor of different origin of these groups of species. In turn, similarity of the C-banding patterns of Ae. columnaris and Ae. triaristata chromosomes suggested that they were derived from a common ancestor. A diploid species Ae. umbellulata was the U-genome donor of Ae. columnaris and Ae. triaristata;however, the donor of the second genome of these species was not determined. We assumed that these tetraploid species occurred as a result of introgressive hybridization. Similarity of the C-banding patterns of chromosomes of Ae. recta and its parental species Ae. triaristata and Ae. uniaristata indicated that the formation of the hexaploid form was not associated with large modifications of the parental genomes.     

Molecular analysis of the phylogenetic relationships among the diploid aegilops species of the section Sitopsis

RAPD analysis was used to study the intraspecific variation and phylogenetic relationships of S-genome diploid Aegilops species regarded as potential donors of the B genome of cultivated wheat. In total, 21 DNA specimens from six S-genome diploid species were examined. On a dendrogram, Ae. speltoides and Ae. aucheri formed the most isolated cluster. Among the other species, Ae. searsii was the most distant while Ae. longissima and Ae. sharonensis were the closest species. The maximum difference between individual accessions within one species was approximately the same (0.18-0.22) in Ae. bicornis, Ae. longissima. Ae. sharonensis, and Ae. searsii. The difference between the clusters of questionable species Ae. speltoides and Ae. aucheri corresponded to the intraspecific level; the difference between closely related Ae. longissima and Ae. sharonensis corresponded to the interspecific level. The section Sitopsis of the genus Aegilops includes six diploid species containing the S genome, which is regarded as an ancestor of the B genome of cultivated wheat. The species of the section are thought to be closest to the genus Triticum. Note that the taxonomic status of some forms of the section Sitopsis is questionable. For instance, Ae. speltoides and Ae. aucheri are variously considered as individual species or as a single species, Ae. speltoides. The situation with Ae. longissima and Ae. sharonensis is similar. Thus, although the group includes only diploid species and is well studied morphologically, its phylogeny and taxonomy are still questionable.     

Productivity of natural and artificial containers for Aedes polynesiensis and Aedes aegypti in four American Samoan villages

Six mosquito species were identified in a survey of containers associated with 347 households in four villages in American Samoa. Aedes polynesiensis Marks (Diptera: Culicidae) and Aedes aegypti (L) were the most abundant species, representing 57% and 29% of the mosquitoes identified. Culex quinquefasciatus (Say), Culex annulirostris (Skuse), Aedes oceanicus (Belkin) and Toxorhynchites amboinensis (Doleschall) were also found. Aedes aegypti and Ae. polynesiensis showed distinct differences in their use of containers, preferring large and small containers, respectively. By contrast with previous studies, Ae. polynesiensis utilized domestic and natural containers with equal frequency, whereas Ae. aegypti continued to be found predominantly in domestic containers. Only 15% of containers holding immature mosquitoes included pupae and fewer than 10 Aedes spp. pupae were found in most containers with pupae. An estimated 2289 Ae. polynesiensis and 1640 Ae. aegypti pupae were found in 2258 containers. The presence of both species in the same container did not affect the mean density of either species for larvae or pupae. Glass jars, leaf axils, tree holes and seashells produced few Aedes spp. pupae in any of the study villages. Overall, 75% of Ae. polynesiensis pupae were found in buckets, ice-cream containers and tyres, with <7% being produced in natural containers, whereas 82% of Ae. aegypti pupae were found in 44-gallon (US) drums ( approximately 166L), buckets and tyres. Source reduction efforts targeting these container types may yield significant reductions in both Ae. polynesiensis and Ae. aegypti populations in American Samoa.     

RAPD analysis of the intraspecific and interspecific variation and phylogenetic relationships of <Emphasis Type="Italic">Aegilops</Emphasis> L. species with the U genome

RAPD analysis was used to study the genetic variation and phylogenetic relationships of polyploid Aegilops species with the U genome. In total, 115 DNA samples of eight polyploid species containing the U genome and the diploid species Ae. umbellulata (U) were examined. Substantial interspecific polymorphism was observed for the majority of the polyploid species with the U genome (interspecific differences, 0.01–0,2; proportion of polymorphic loci, 56.6–88.2%). Aegilops triuncialis was identified as the only alloploid species with low interspecific polymorphism (interspecific differences, 0–0.01, P = 50%) in the U-genome group. The U-genome Aegilops species proved to be separated from other species of the genus. The phylogenetic relationships were established for the U-genome species. The greatest separation within the U-genome group was observed for the US-genome species Ae. kotschyi and Ae. variabilis. The tetraploid species Ae. triaristata and Ae. columnaris, which had the UX genome, and the hexaploid species Ae. recta (UXN) were found to be related to each other and separate from the UM-genome species. A similarity was observed between the UM-genome species Ae. ovata and Ae. biuncialis, which had the UM genome, and the ancestral diploid U-genome species Ae. umbellulata. The UC-genome species Ae. triuncialis was rather separate and slightly similar to the UX-genome species.     

Salt Tolerance in the Triticeae: K/Na Discrimination in Aegilops Species

Inorganic ion concentrations were measured in the leaves ofAegilops species growing in 50 or 75 mol m^–3 NaCl (+2.5or 3.75 mol m–3 CaCl₂). The low leaf Na and high leafK concentrations characteristic of the enhanced K/Na discriminationcharacter, originally found in Aegilops squarrosa and in hexaploidwheat, were also found in other Aegilops species containingthe D genome, but not in Ae. ventricosa. The S genome diploidAegilops species (section Sitopsis) all lacked the enhancedK/Na discrimination trait, as did the C genome species Ae. caudataand the N genome species Ae. uniaristata. Most of the U genomespecies (section Polyeides), except Ae. biuncialis, Ae. kotschyiand Ae. variabilis, also exhibited the trait. Examination ofamphiploid hybrids suggested that the trait was dominant incrosses involving Ae. squarrosa or Ae. umbellulata with otherspecies in which the trait was absent. Key words: Salt, ion transport, D genome, Aegilops spp     

Species relationships and genetic variation in the diploid wheats (Triticum,Aegilops) as revealed by starch gel electrophoresis

Twenty enzyme loci were examined in the diploid species ofTriticum andAegilops for allelic variation by starch gel electrophoresis. SectionSitopsis, including the five species,Ae. speltoides, Ae. lingissima, Ae. sharonensis, Ae. bicornis andAe. searsii form a close subgroup withAe. speltoides slightly removed from the others.T. monococcum s. lat., was found to be closest to the species of theSitopsis group.Ae. comosa, Ae. umbellulata andAe. uniaristata form a second subgroup withAe. caudata most closely related to these species.Ae. squarrosa appears almost equally related to all of the species, showing no special affinity for any one species group. Nineteen out of twenty loci examined were polymorphic with a mean of 6.7 alleles per locus. Species could be, for most loci, characterized by the presence of predominant alleles. A conspicious genetic characteristic ofTriticum-Aegilops is the sharing of these predominant alleles between species. Within species variation is characterized by a diffuse distribution of secondary alleles.     

A catalog of mosquito species (Culicidae family) from the Asian region of Russia

A new checklist of mosquitoes (Culicidae) recorded in the Asian part of Russia includes 79 species. The checklist is provided with taxonomic comments and compared with ones compiled by previous authors. In a comparison to the checklist of Kukharchuk (1980) including 73 species, 10 species are added into the present checklist and 6 species mentioned by this author are excluded, as far they were not actually found in Asian part of Russia. The names of 9 species are chanced according to the International Code of Zoological Nomenclature (1966). In the checklist of Stojanovich and Scott (1995) including 64 species, 5 species were included erraneously and 21 species were missed. The classification and valid species names are listed according to the Catalog of the Mosquitoes of the World (Knight, Stone, 1977) and its supplements (Knight, 1978; Ward, 1984, 1992; Gaffigan, Ward, 1985), except 5 species. These species (Aedes implicatus, Ae. esoensis, Ae. rossicus, Ae. albescens, Ae. subdiversus) are considered in the comments to the checklist.     

Differential lipid reserves influence host-seeking behaviour in the mosquitoes Aedes cantans and Aedes punctor

ipid reserves of bait-caught female Ae.cantans and Ae.punctor mosquitoes (Diptera: Culicidae) were significantly higher than in teneral females. Female Ae.cantans given access to 10% w/v sucrose solution post-emergence showed an ability to synthesize lipid and, after 192 h, they were willing to take a bloodmeal from a human volunteer. At this point, mean lipid reserves were not significantly different from mean lipid reserves of bait-caught females. Prior to 192 h, females would not take a bloodmeal and lipid reserves were significantly lower than in bait-caught females. Female Ae.punctor given access to 10% w/v sucrose solution post-emergence also showed an ability to synthesize lipid. Females of this species were willing to feed from a human host after only 48 h, at which point lipid content was not significantly different from that in bait-caught females. The level of lipid reserves in females coming to bait differs significantly between species: Ae.cantans has lipid reserves approximately double those of Ae.punctor . In addition, Ae.punctor is able to synthesize lipid to a level comparable with that found in bait-caught females after only 24 h, whilst it takes 192 h for Ae.cantans females to synthesize the amount of lipid found in host-seeking females, when allowed free access to sugar. Physiological differences in lipid synthesis and the level of lipid reserves required may therefore explain the differences observed between the species in the time taken to initiate host seeking.     

Geographic and ecological distribution of the dengue and chikungunya virus vectors Aedes aegypti and Aedes albopictus in three major Cameroonian towns

Aedes albopictus (Diptera: Culicidae) was first reported in Central Africa in 2000, together with the indigenous mosquito species Aedes aegypti (Diptera: Culicidae). Because Ae. albopictus can also transmit arboviruses, its introduction is a public health concern. We undertook a comparative study in three Cameroonian towns (Sahelian domain: Garoua; equatorial domain: Douala and Yaoundé) in order to document infestation by the two species and their ecological preferences. High and variable levels of pre‐imaginal Ae. aegypti and Ae. albopictus infestation were detected. Only Ae. aegypti was encountered in Garoua, whereas both species were found in Douala and Yaoundé, albeit with significant differences in their relative prevalence. Peridomestic water containers were the most strongly colonized and productive larval habitats for both species. No major differences in types of larval habitat were found, but Ae. albopictus preferentially bred in containers containing plant debris or surrounded by vegetation, whereas Ae. aegypti tended to breed in containers located in environments with a high density of buildings. These findings may have important implications for vector control strategies.     

The first report of Aedes (Stegomyia) albopictus in Haiti

Aedes albopictus was found in six of the 10 departments of Haiti and in 14 of the 35 communes surveyed. The survey found the larvae of Ae. albopictus in 13 different types of containers. Used tires and tins were by far the most common breeding sites used by this mosquito species. At the breeding sites, Ae. albopictus was associated with other mosquito species, such as Aedes aegypti, Culex nigripalpus and Aedes mediovittatus. The highest proportion of association was with Ae. aegypti. This study represents the first report of Ae. albopictus in Haiti.     

Midgut and salivary gland barriers to La Crosse virus dissemination in mosquitoes of the Aedes triseriatus group

Vector competence for La Crosse virus (LACV) was compared for four species in the Aedes (Protomacleaya) triseriatus group: Ae. triseriatus (Say), Ae. hendersoni Cockerell, Ae. zoosophus Dyar and Knab and Ae. brelandi Zavortink (Diptera: Culicidae). Rates of replication and dissemination of virus in the mosquito hosts were compared and rates of oral transmission of virus to suckling mice were determined. Barriers to virus dissemination which limited the ability of each species to transmit virus were identified. Ae. zoosophus displayed the highest vector competence for LACV. Both infection and transmission rates were high: 99% and 85% respectively; no significant barriers to LACV were found. Disseminated infection of Ae. triseriatus with LACV was controlled primarily be a midgut escape barrier. When virus was introduced directly into the haemocoel, transmission rates were significantly increased (37% v. 79%). Ae. hendersoni showed high susceptibility to LACV infection but a very low rate of oral transmission (7%). Ae. brelandi was also highly susceptible to infection by LACV and transmitted virus at an intermediate rate (27%). Modulation of vector competence in both Ae. hendersoni and Ae. brelandi resulted from a salivary gland escape barrier. As these four species of mosquitoes comprise a closely related monophyletic series, their differences of vector competence for LACV provide an excellent model for studying the genetic basis of the barriers involved.     

High-molecular-weight glutenin subunits in the Cylindropyrum and Vertebrata section of the Aegilops genus and identification of subunits related to those encoded by the Dx alleles of common wheat

The high-molecular-weight (HMW) glute-nin subunit composition of seven species from the Cylindropyrum and Vertebrata sections of the Aegilops genus was studied using SDS-PAGE and Western blot analysis. Two subunits were detected in Ae. caudata and three in Ae. cylindrica. In both species, subunits showing electrophoretic mobility similar to that of 1Dx2 were present. Western blot analysis using a monoclonal antibody (IFRN 1602) specific for the 1Ax and 1Dx subunits of bread wheat showed that the 1Dx-like subunit of Ae. caudata gave only a weak reaction. This indicates that Ae. caudata expresses subunits which are more distantly related to the 1Dx subunits. Two subunits were detected in each of the 60 accessions of Ae. tauschii, including several 1D^tx subunits showing different electrophoretic mobilities from those of the 1Dx subunits commonly found in bread wheat. All of the 1D^tx subunits reacted strongly with IFRN 1602, confirming their close relationship to the 1Dx subunits of bread wheat. Three subunits were found in Ae. crassa (6 x), four in Ae. ventricosa and Ae. juvenalis and five in Ae. vavilovii. In these four species, the subunits that showed electrophoretic mobility similar, or close, to that of 1Dx2 all reacted with IFRN 1602. In addition, Ae. ventricosa contained a subunit showing electrophoretic mobility slower than that of 1Dx2.2, which also reacted with IFRN 1602. These results suggest that the D-genome component in the multiploid Aegilops species express at least one HMW glutenin subunit that is structurally related to the 1Dx subunits of bread wheat. Received: 5 November 1999 / Accepted: 12 February 2000     

Aquatic thermal conditions predict the presence of native and invasive rock pool Aedes (Diptera: Culicidae) in the southern Appalachians,U.S.A.

The native rock pool mosquito, Aedes atropalpus (Coquillett), and the invasive Aedes japonicus (Theobald) have been found in many types of artificial and natural containers throughout North America. Little is known about the ecology of these two species in habitats where they co‐occur, although multiple investigators have reported the decline of the native species concurrent with the introduction and spread of the invasive species. Here we report the results of riverine rock pool collections (n=503) in the southern Appalachian Mountains between 2009‐2015. Surface water temperatures strongly predicted the presence of each species across a broad range of observed temperatures (11‐39.8° C). For every unit of increase in temperature (°C) the odds of collecting Ae. atropalpus larvae increased by 0.34 while the odds of collecting Ae. japonicus larvae decreased by 0.28. No Ae. japonicus larvae or pupae were collected at temperatures greater than 36° C; however, immature Ae. atropalpus were found in rock pools with temperatures up to 39.8° C. In contrast, Ae. japonicus were highly abundant in cooler rock pools (<17° C) where Ae. atropalpus were infrequent or absent. Our findings suggest that in spite of the successful invasion by Ae. japonicus, Ae. atropalpus remains well established in the southern Appalachian Mountains. Given the strong correlation of temperature with the presence of the two species and the contrasting absence of each species at observed temperature extremes, the role of thermal conditions should be carefully explored in the context of other ecological factors likely influencing the range and abundance of these mosquitoes.     

Expression of Chironomus riparius serine-type endopeptidase gene under di-(2-ethylhexyl)-phthalate (DEHP) exposure

Environmental stressors can induce changes in gene expression that can be useful as biomarkers. To identify potential biomarkers of water quality, we characterized full-length cDNA sequences of the serine-type endopeptidase (SP) gene from Chironomus riparius. Their expression was analyzed during different life-history stages and in response to treatment with various concentrations of di(2-ethylhexyl) phthalate (DEHP) for short and long periods of time. A comparative molecular and phylogenetic investigation was then conducted among different orders of insects using sequence database analysis. The sequence of the C. riparius SP gene was found to be most closely related to the sequence of SPs isolated from Aedes aegypti. In addition, the basal level of C. riparius SP mRNA was more highly expressed in larvae than in other life-history stages. However, the expression of C. riparius SP was primarily limited to the gut in larvae. When the effects of short-term exposure to DEHP were evaluated, C. riparius SP gene expression decreased within 1 h of treatment, regardless of dose. We also investigated expression of the C. riparius SP gene following long-term DEHP exposure (10 days) and found that it decreased significantly across all DEHP dosages. Finally, the response of the SP gene was more sensitive in C. riparius that were exposed to low concentrations of DEHP than in those that were exposed to high concentrations. These results show that suppression of the C. riparius SP gene by DEHP is as a potential biomarker that could be useful for monitoring aquatic quality.     

AFLP-based analysis to study genetic variability and relationships in the Spanish species of the genus Aegilops

Amplified fragment length polymorphism (AFLP) DNA markers were used to characterize the genetic diversity and relationships in wild species of the genus Aegilops. Fifty populations, which included the species Aegilops biuncialis (UUMM), Ae. neglecta (UUMMNN), Ae. ovata (UUMM), Ae. ventricosa (DDNN) and Ae. triuncialis (UUCC) were selected. These populations are distributed in the Iberian peninsula and Balearic islands. Five AFLP selective primer combinations generated a total of 527 amplification products of which 517 (98.10%) detected polymorphisms. Aegilops neglecta showed the least variation in contrast with Ae. biuncialis that presented the highest degree of polymorphism. Genetic relationships within the populations were evaluated by generating a similarity matrix based on the Jaccard index. In the resulting phenogram Ae. ventricosa appears segregated from the other species, probably owing to the influence of the D genome. The species sharing the U genome are located in the main cluster. The branching pattern of the U genome group reflects the proximity of the species sharing the M genome. Ae. biuncialis and Ae. ovata are clearly separated suggesting that the super index system should be used to differentiate the M genomes of both species. The variation among populations within species in relation to their geographical origin and results previously obtained by the authors using biochemical and molecular markers are discussed.     

中国武陵山地区淡水钩虾属一新种(甲壳纲:端足目:钩虾科)

记述了采自湖北省宣恩县长潭河的淡水沟虾1新种,溪水钩虾Gammarus riparius sp.nov.。该种隶属于G.balcanicus-group,其鉴别特征为：第2触角鞭节无鞋形感觉器,4－5腹节背部无刺或刚毛。文中对新种的形态特征和与近似种的区别均有详细的论述,并附有详细的特征图。新种模式标本保存在中国科学院动物研究所。     

Genetics of speciation in the Aedes (Stegomyia) scutellaris group (Diptera: Culicidae) V. Chromosomal relationships among five species

A comparison was made of karyotypes of 5 species in the Aedes scutellaris group and their hybrids. All species had 3 distinct pairs of metacentric chromosomes (2n=6). These were of similar lengths in Ae: malayensis and Ae. alcasidi, and in Ae. polynesiensis and Ae. pseudoscutellaris. However, chromosome 1 in Ae. polynesiensis and Ae. kesseli, and chromosome 2 in Ae. pseudoscutellaris and Ae. kesseli were of unequal lengths. Meiotic analyses revealed that chromosome asynapsis was frequently seen in species hybrids. There was a significant variation in chiasma frequencies between species and their hybrids. However, the mean chiasma frequency was species specific. In addition, the mean chiasma frequency of species hybrids and the extent of chromosomal asynapsis provided a measure of genetic homology between species. Based on the assumption that a dicentric bridge and an acentric fragment were due to a single crossover within a paracentric inversion loop the following conclusions are made. Ae. malayensis and Ae. alcasidi are polymorphic for one paracentric inversion in chromosome 1. Ae. polynesiensis and Ae. pseudoscutellaris, and Ae. pseudoscutellaris and Ae. kesseli are fixed for one paracentric inversion in chromosome 2. Similarly, Ae. polynesiensis and Ae. kesseli are fixed for one paracentric inversion in chromosome 1. These chromosomal differences between species are discussed with respect to hybrid fertility data reported earlier.