Karyotypic characteristics of the genus Prosimulium Roub. (Simuliidae) and the problems of systematics

A comparative-karyologycal study of 12 species of black flies of the genus Prosimulium was carried out. Species referring to the groups hirtipes and macropyga have similar karyotypical characteristics differing in general in the degree of ploidy of chromosomal sets. Species which form the group alpestre possess peculiar karyologycal characters occupying due to this an intermediate position between the genera Prosimulium and Helodon. They should be separated into a distinct superspecies taxon, Ahaimophaga Chubareva et Rubzov gen. n. P. multicaulis differs karyotypically from other species of the genus Prosimulium but displays a great resemblance to species of Helodon; due to this it should be assigned to the latter.     

Triploidy in populations of three species of black flies of the genus Prosimulium roubaud (Diptera, Simuliidae)]

Karyotypes of 94 larvae belonging to species of black flies of the genus Prosimulium Rouband were studied on aceto-orcein stained squashes of 94 larvae belonging to three species of Prosimulium: P. isos Rubzov, P. pecticrassum Rubzov, and P. pamiricum Chubareva et Petrova. All the larvae appeared to be triploid parthenogenetic females, with no males being found. The structural peculiarities of these polytene chromosomes suggest a heterozygous nature of the examined larvae.     

Description of males of <Emphasis Type="Italic">Prosimulium candicans</Emphasis> Rubzov, 1956 (Diptera: Simuliidae)

Previously unknown males of Prosimulium candicans are described. Belonging of this species to the genus Prosimulium Roubaud, 1906, but not to the genus Taeniopterna Enderlein, 1925, is confirmed.     

Morphology of the blackfly species group macropyga of the genus Prosimulium roubaud, 1906, and re-establishment of the generic name Taeniopterna Enderlein, 1925 for this group (Diptera: Simuliidae)

The genus Taeniopterna with the types species Melusina macropyga Lundstrom, 1911 was proposed by Enderlein in 1925. Later this taxon was considered as the species group macropyga in the genus Prosimulium Roubaud, 1906 by many authors (Rubzov, 1956; Crosskey et Howard, 1997; Adler et al., 2004, and others). However, differences between this group and the remaining species of Prosimulium s. str. (species group hirtipes/mixtum) seem to be not lesser, than those between other genera (or subgenera) of the tribe Prosimuliini (in our sense), namely Helodon Enderlein, 1921, Urosimulium Contini, 1963, Parahelodon Peterson, 1970, and Distosimulium Peterson, 1970. Taeniopterna differs from other genera of Prosimuliini by the following characters. Imago differs from all other genera in having shortened proboscic (1.5 times shorter than clypeus, while in other genera it is of the same length with clypeus). It differs from all genera except Helodon in having relatively prolonged and lightly pointed distally wings (in other genera wings are wide and rounded distally). Male differs from all other genera of the tribe, except Urosimulium, in having narrow frons between the eyes. It differs from the Urosimulium male by conic gonostyles (in Urosimulium gonostyles bear the large heel). Female differs from all other genera of tribe by very small spermatheca (1/3-1/5 of the lenght of the branch of genital fork (while in other genera spermatheca is equal or longer, than the branch of genital fork) and by the absence of serration on maxillae and mandibles. Female also differs from other genera of the tribe, except Prosimulium, by very long hypogynal valves and by missing or very small and pressed basal tooth of claws (in Helodon, Urosimulium, Parahelodon, and Distosimulium hypogynal valves are short and rounded, basal tooth of claws is moderate or large and put aside). It differs from Prosimulium by smaller head (more narrow than thorax, while in Prosimulium head is near equal by width with thorax) and by absence of sclerotization on the medial edges of hypogynal valves. Larva differs from all other genera of the tribe, except Prosimulium, in having long dorsoventral projections of wide sclerotized band of prothorax (in other genera this band is narrow and without projections). It differs from Prosimulium by another pattern of the hypostomal teeth. Pupa differs from all other genera of the tribe, except Distosimulium, by cocoon covering all the pupal body (in other genera cocoon covers only posterior part of the pupal body). It differs from Distosimulium by long and strong caudal thorns (in Distosimulium caudal thorns are of moderate length and more thin). These and some other characters give the base for the proposition to consider the species group macropyga as a a separate genus Taeniopterna Enderlein, 1925. A list of Taeniopterna species is given.     

The fossil pupa Simulimima and the evidence it provides for the Jurassic origin of the Simuliidae (Diptera)

Abstract. Examination of the Middle Jurassic dipteran pupal fossil Simulimima grandis Kalugina shows it to possess the pupal diagnostic characters of Simuliidae and to be not significantly distinguishable from the pupa of modern Prosimulium . The nominal monotypic genus Simulimima Kalugina is assigned to that family, but provisionally maintained as valid in the absence of knowledge of associated life stages. The holotype and only specimen of S. grandis is redescribed and illustrated photographically and by line drawings, with emphasis on features which pertain to its family placement. Unambiguous assignment to Simuliidae implies an earlier Mesozoic origin for the blackflies than previously evidenced by available fossils, and it is suggested that the origins of the Simuliidae go back to Lower Jurassic times.     

Cytotaxonomy of the Prosimulium (Diptera: Simuliidae) of Western Asia

Chromosomal analysis of more than 500 larval black flies from 19 sites in Armenia and Turkey revealed five taxa in the Prosimulium hirtipes group: Prosimulium frontatum Terteryan, Prosimulium rachiliense Djafarov cytoform ‘A,’ P. rachiliense Djafarov cytoform ‘B,’ Prosimulium tomosvaryi (Enderlein), and a new species of Prosimulium. To associate the names rufipes (Meigen) and tomosvaryi with cytological entities, larvae from the respective type localities in Germany were characterized chromosomally. Prosimulium frontatum is restricted to the Caucasus Mountains where studied populations have five unique inversions. It is most closely related to cytoforms ‘A’ and ‘B’ of P. rachiliense, the three taxa sharing one unique inversion. The two cytoforms of P. rachiliense are separated by about 1200 km, obscuring decisions about their reproductive isolation. The names rachiliense and possibly pronevitschae Rubtsov apply to cytoform ‘A’ in Armenia, whereas the name fulvipes (Edwards) might apply to cytoform ‘B’ in Turkey and to material formerly identified in Turkey as P. rufipes. Populations of P. tomosvaryi in Armenia are chromosomally distinct from previously studied populations in Europe and Morocco, although tied to European and Turkish populations by a shared X‐linked inversion. We conservatively view Armenian, European, and Turkish populations of P. tomosvaryi as a single, polymorphic species. A new species, chromosomally related to P. hirtipes (Fries) and P. tomosvaryi by two uniquely shared inversions, was discovered in Turkey. © 2014 The Linnean Society of London     

A karyotypic analysis of 2 species of blackflies in the genus Prosimulium (Diptera: Simuliidae) from the Kola Peninsula and Kamchatka

Significant karyotypic differences between the triploid (3n = 9) Prosimulium macropygum Lundstr?m and the diploid (2n = 6) P. macropygum ventosum Rubzov have been found. It is suggested to consider the latter taxon as an independent species P. ventosum.     

Comparison of mitochondrial DNA sequences of seven morphospecies of black flies (Diptera: Simuliidae)

Universal primers constructed from the 16S ribosomal RNA gene in the Drosophila yakuba mitochondrial genome were successfully used to amplify, via the polymerase chain reaction, the homologous region of mitochondrial DNA from seven black fly morphospecies. Amplification was achieved from single larval salivary glands and from single adults preserved in Carnoy's fixative (ethanol - acetic acid, 3:1), allowing DNA sequences and polytene chromosome banding pattern data to be gathered from the same individuals. Nucleotide sequences of the amplified DNA segment (347 base pairs) were obtained from all the species examined. As in Drosophila, the nucleotide base composition of the sequenced segment from black flies had a high adenine (A) and thymine (T) content (A + T on average comprised 77% of all nucleotides.). Nucleotide differences among the seven species were observed at 59 positions (55 nucleotide substitutions and 4 deletions). There were more transversion differences than transition differences both among and within genera; the proportion of transversions was higher between genera than within genera. Most transversion differences were A----T type, comprising 79% of all transversion differences and 50% of all sequence differences. Phylogenetic inference based strictly on transversion differences confirmed traditional generic and tribal groupings, i.e., Prosimulium fuscum (Syme & Davies) is close to Prosimulium magnum (Dyar & Shannon); Simulium decorum (Walker), Simulium venustum s.l. (Say), and Simulium vittatum s.l. (Zetterstedt) are close to each other; Stegopterna mutata (Malloch) and Cnephia dacotensis (Dyar & Shannon), which belong to the tribe Cnephiini, are grouped together.     

Effects of land use on black fly assemblages (Diptera: Simuliidae) in submontane rivers (West Carpathians, Slovakia)

The effects of land use on black fly assemblages were investigated in submontane rivers (the Ľubochnianka River, the Revúca River, upper Váh River catchment) in the Carpathians. We recorded 11 black fly species in the Ľubochnianka River and 10 species in the Revúca River. Land use differs between the catchments; the Ľubochnianka is a primarily forested catchment, and the Revúca is markedly deforested catchment. Fifteen environmental variables were analysed. Based on the results provided by CANOCO, phosphorus level and stream slope are the most important variables and have significant influences on the variability of black fly assemblages. In spring, Prosimulium rufipes occurred along the entire lengths of the streams. The black fly assemblage of the Revúca River differs from the assemblage of the Ľubochnianka River mainly by its higher abundances of Simulium variegatum and Simulium ornatum, by the presence of Simulium carthusiense, and by the absence of Prosimulium hirtipes.     

Species makeup and ecological characteristics of the black flies (Simuliidae) in the region of the Baikal-Amur mainline construction

18 species of black flies were registered from the north of the Amur district. It was found that the eternal frost affects considerably the species composition, abundance and phenology of black flies in this region. Prosimulium isio, Gnus cholodkovskii, G. rostratum and Sch?nbaueria subpusilla are bloodsucking species; of them G. cholodkovskii is most abundant. Data are given on the breeding places of bloodsuckers and seasonal dynamics of their flight.     

Comparison of water ingestion between black flies (Simuliidae) and a mosquito (Aedes aegypti; Culicidae) using radiolabelled glucose

Ingestion of water by larvae of the black flies Simulium verecundum, Prosimulium mixtum/fuscum and Cnephnia dacotensis and by larvae of the mosquito Aedes aegypti was studied with radiolabelled glucose as a tracer. Extremely low ( 200 dpm/3 h) radiolabel uptake occurred in the black flies species, while Aedes aegypti, a species that is known to drink, had high radiolabel counts (> 6000 dpm/3 h). Radiolabel uptake by S. verecundum did not change for larvae fed in absence of current or with plugged mouthparts versus normal larvae. Radiolabel uptake by Aedes aegypti larvae with plugged mouthparts was < 3% of radiolabel uptake in normal larvae. Aedes aegypti was able to ingest the soluble glucose. Simulium verecundum, Prosimulium mixtum/fuscum and Cnephia dacotensis were unable to ingest the soluble sugar. The rationale for this difference is in the different filter-feeding mechanism of Culicidae and Simuliidae.     

New subspecies of Prosimulium macropyga korshunovi Patrusheva subsp. n. (Diptera, Simuliidae) from the Polar Urals]

A new subspecies, Prosimulium macropyga korshunovi Patr. subsp. n., from the Polar Urals differs from other forms of P. macropyga (Lundstr.) and allied species in having two dark longitudinal stripes on the dorsum and by the structure of genitalia in adult insects, by the number of setae in the great flabellum, by the structure of submentum and shape of the ventral incision in larvae and by the branching pattern of respiratory threads in pupa.     

Some effects of mermithid parasitism on the larval blackflies Prosimulium mixtum fuscum and Simulium venustum

Histochemical studies on field-collected specimens of larval blackflies showed no significant differences in endocrine activity between mermithid-infected and uninfected Prosimulium mixtum fuscum larvae of similar body dimensions. In Simulium venustum, mermithid parasitism significantly increased the nuclear DNA/RNA activity of the corpus allatum gland as well as the volume and amount of stored neurosecretory material in the corpus cardiacum gland. A marked decline in glycogen concentration and the amount of fat body tissue was evident in both infected simuliid species. Fat body nucleic acid activity was unaffected by mermithid parasitism. The significance of these effects of mermithid parasitism is discussed with regard to the host-parasite relationship.     

Oviposition habits of a univoltine blackfly, Prosimulium kiotoense (Diptera: Simuliidae), in Kyushu, Japan

Oviposition habits of a univoltine mammalophilic blackfly, Prosimulium kiotoense Shiraki, were investigated at a stream in Kyushu Island, Japan. The flies oviposited on bryophyte mosses growing on river bank rock surfaces. The eggs were laid singly, but large irregular egg masses were often formed because many females oviposited within the same small areas. Wet sites with dense bryophyte cover at heights between 0 and 15 cm above water level were selected for oviposition. Oviposition activity was observed in the latter half of April. P. kioteonse females came to the site to lay eggs after 11.00 hours in the morning, when air temperature rose to about 15 degrees C. Peak ovipositional activity occurred between 12.00 and 14.00 hours.     

Seasonal fluctuations of macroinvertebrate drift in a South Carolina Piedmont stream

The seasonal fluctuations of larval macroinvertebrate drift, exuvial drift and larval benthic density were quantitatively examined over a 1-year period in a fourth order, spring-fed stream in the Piedmont area of South Carolina. The drift was dominated by the mayfly Baetis spp. and by two species of blackfly (Prosimulium mixtum and Simulium jenningsi). Peak drift densities were noted during early spring and especially late summer. Strong correlations were noted between larval drift densities and exuvial drift, indicating a relationship between drift and seasonal growth and emergence patterns. Seasonal trends in drift and benthic densities, though less strongly correlated, were also generally similar.     

End-products of behaviour versus behavioural characters: a phylogenetic investigation of pupal cocoon construction and form in some North American black flies (Diptera: Simuliidae)

Cocoon spinning was analysed, using video recording and playback, in eighteen Nearctic black fly species, comparing nine Simulium species, six Eusimulium species, Stegopterna mutata, Cnephia dacotensis and Prosimulium mixtum. Fourteen behavioural characters were revealed that produced twenty-two equally parsimonious trees (CI = 0.93, RI = 0.96). Another tree was constructed on the basis of five characters relating to the cocoon structure (end-product characters). The goal of the study was to determine whether characters relating to behavioural components of black fly cocoon spinning or those based on end-products of the behaviour are superior for revealing phylogenetic relationships. This was accomplished by comparing both data sets to a phylogeny constructed with the use of cytological and morphological characters. If taxa are grouped according to end-products (the cocoons) there are some spurious groupings. The behavioural analysis only required one extra step to duplicate the morphological and cytological tree. In the case of black flies, it is more informative to use characters resulting from the analysis of the cocoon spinning behaviour than cocoon morphology.     

Emergence of blackflies (Diptera: Simuliidae) from a small forested stream in Ontario

Three species of blackflies were found in emergence-trap samples taken overa period of 8 months from a second-order, forested, cold-stenothermal stream in southern Ontario. The emergence phenologies of the two common species, Prosimulium mixtum and Stegopterna mutata, are described and compared with their phenologies in other streams in North America. Hypotheses are presented for the poor faunal diversity and prolonged emergence of the two species in the stream studied. Emergence data are used to describe the pupal distribution in the stream.Wing-length measurements showed a distinct dimorphism in P. mixtum: females were larger than males. Adult size (except of P. mixtum females) varied among sampling sites in the stream and, in the case of S. mutata, this variation was time dependent.     

Field and laboratory observations on a cytoplasmic polyhedrosis virus of blackflies (Diptera: Simuliidae)

Larval blackflies were sampled from streams in Newfoundland, Canada, from April 1974 through October 1975 for the presence of cytoplasmic polyhedrosis virus (CPV). CPV was found in Cnephia mutata, Prosimulium mixtum fuscum, Simulium tuberosum, S. venustum, and S. vittatum. Virus was most common in C. mutata occurring in seven of nine streams from which this host was sampled and with an incidence of infection up to 54%. Infections were rarer in other species, occurring in 10–30% of the streams sampled, depending on host species. Incidence of infection was usually less than 1% and never exceeded 5% for any species other than C. mutata. Results of preliminary infectivity studies are given, and the bionomics of the disease in nature are discussed.     

Evolution of larval head-fans in Simuliidae (Diptera) as inferred from the structure and biology of Crozetia crozetensis (Womersley) compared with other genera

The life stages of C. crozetensis whose larvae have raking head-fans are described. Functional anatomical study of the fans compared with the filtering fans of normal Simuliidae together with SEM study of first instar larvae of Gymnopais, Twinnia and Prosimulium enable the evolution of cephilic fans to be inferred as follows: a group of lateral labral bristles evolved in two directions:

• 1. 

  To complete loss in Gymnopais and Twinnia whose ancestors therefore never possessed fully developed fans.
• 2. 

  Elaboration of the group of bristles first into raking organs, as in Crozetia , and later into even more complex filtering organs.

It is shown that unflexing of Simuliid fans depends on elastic energy stored in resilin-containing components deformed during flexing.
Adults of Crozetia mate on stones in streams on lie de la Possession, Ties Crozet. The females are non-biting and rest near streams while their eggs mature, thus forming a sub-Antarctic parallel to certain sub-Arctic Simuliidae.     

Use of inter-simple sequence repeat (ISSR) markers for discrimination between and within species of blackflies (Diptera: Simuliidae)

The present study is the first report of fingerprinting in blackflies (Diptera: Simuliidae), using inter-simple sequence repeat (ISSR) markers. Among five primers tested, three tetranucleotide repeat primers ((GACA)₄, (ACTG)₄, (ACAG)₄) generated a high proportion of polymorphic bands. Seven species representing various genera, subgenera or species groups were compared. No similar profiles were found. Intraspecific and interspecific banding patterns were analysed for two species in the Prosimulium hirtipes (Fries, 1824) species group and four species in the Simulium variegatum (Meigen, 1818) species group. The UPGMA cluster analysis based on Jaccard’s coefficient demonstrated the intraspecific and interspecific diversity and the resolving power of the ISSR markers to differentiate blackfly species and populations. In Simulium maximum (Knoz, 1961), geographically defined populations were successfully discriminated.