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.     

Five Simuliidae (Diptera) from West Cameroon

The male, female, pupa and larva of a new phoretic species of Simulium are described. A new species-group is established for this species and S.diceros, and its systematic position is discussed. Two other new species of Simulium are described from pupal material, and new forms of S.palmeri and S.berghei are recorded.     

Simuliidae (Diptera) of Sabah (British North Borneo)

This paper is based on collections made in Sabah by John Smart and on an examination of named material (types) in the British Museum (Natural History), London.
Segregates discussed comprise:(1) six new species, (2) five named species from the area, described by the late F. W. Edwards (1933).     

Durability of Simuliid Silk Pads (Simuliidae,Diptera)

A central aspect of simuliid adaption to life in moving water is a silky secretion which they produce in their salivary glands. This secretion is spread on the substrate surface thereby enabling adhesion of the posterior abdominal hooks of the larvae to the substrate surface. Therefore, silk pads are a prerequisit for simuliid filter‐feeding as well as any kind of locomotive activity. If silk pad adhesion is weak, larvae risk drifting off, either directly or during locomotion. Properties of the adhesive (=silk) as well as the substrate surface may cause weak adhesion. A specialist such as S. noelleri which has little chance of surviving after drifting off its lake outlet habitat, should have adaptations to reduce this risk. Such an adaptation could be very durable silk pads, giving larvae the chance to be safely attached for a relatively long time. In this study larval silk pads of S. ornatum and S. noelleri were stained using Giemsa's staining procedures. Changes in silk pad structure and traces of rot after 2–33 days of exposure to stream water were recorded and compared. Silk pads of S. ornatum and S. noelleri showed differences which indicate differences in ageing processes and biochemistry of this secretion.     

Phylogenetic relationships within the leaf-mining flies (Diptera: Agromyzidae) inferred from sequence data from multiple genes

The leaf-mining flies (Diptera: Agromyzidae) are a diverse group whose larvae feed internally in leaves, stems, flowers, seeds, and roots of a wide variety of plant hosts. The systematics of agromyzids has remained poorly known due to their small size and morphological homogeneity. We investigated the phylogenetic relationships among genera within the Agromyzidae using parsimony and Bayesian analyses of 2965 bp of DNA sequence data from the mitochondrial COI gene, the nuclear ribosomal 28S gene, and the single copy nuclear CAD gene. We included 86 species in 21 genera, including all but a few small genera, and spanning the diversity within the family. The results from parsimony and Bayesian analyses were largely similar, with major groupings of genera in common. Specifically, both analyses recovered a monophyletic Phytomyzinae and a monophyletic Agromyzinae. Within the subfamilies, genera found to be monophyletic given our sampling include Agromyza, Amauromyza, Calycomyza, Cerodontha, Liriomyza, Melanagromyza, Metopomyza, Nemorimyza, Phytobia, and Pseudonapomyza. Several genera were found to be polyphyletic or paraphyletic including Aulagromyza, Chromatomyia, Phytoliriomyza, Phytomyza, and Ophiomyia. We evaluate our findings and discuss host-use evolution in light of current agromyzid taxonomy and two recent hypotheses of relationships based on morphological data.     

Polytene chromosomes of Simulium craigi (Diptera: Simuliidae)

Simulium craigi Adler and Currie is a polymorphic species based on polytene chromosome banding patterns in the long arm of chromosome III (IIIL). Three cytotypes are described based on the predominant IIIL sequences. These correspond to three broad geographic areas: cytotype CC from Pennsylvania; cytotype AF from Ontario and Manitoba; and cytotype ACF/BCF from New Hampshire. In the absence of sympatric populations, these cytotype differences are best explained by clinal variation within a single species. The relationship of S. craigi to other described members of the S. vernum group is discussed.     

Molecular phylogeny of black flies (Diptera: Simuliidae) from Thailand, using ITS2 rDNA

The sequences of the second internal transcribed spacer (ITS2) of ribosomal DNA (rDNA) were determined for 40 black fly species from Thailand, belonging to 4 subgenera of the genus Simulium, namely Gomphostilbia (12 species), Nevermannia (5 species), Montisimulium (1 species), Simulium sensu stricto (21 species), and an unknown subgenus with one species (Simulium baimaii). The length of the ITS2 ranged from 247 to 308 bp. All black fly species had high AT content, ranging from 71 to 83.8%. Intraindividual variation (clonal variation) occurred in 13 species, ranging from 0.3 to 1.1%. Large intrapopulation and interpopulation heterogeneities exist in S. feuerboni from the same and different locations in Doi Inthanon National Park, northern Thailand. Phylogenetic relationships among 40 black fly species were examined using PAUP (version 4.0b10) and MrBAYS (version 3.0B4). The topology of the trees revealed two major monophyletic clades. The subgenus Simulium and Simulium baimaii were placed in the first monophyletic clade, whereas the subgenera Nevermannia + Montisimulium were placed as the sister group to the subgenus Gomphostilbia in the second monophyletic clade. Our results suggest that S. baimaii belongs to the malyschevi-group or variegatum-group in the subgenus Simulium. The molecular phylogeny generally agrees with existing morphology-based phylogenies.     

Gender-specific bacterial composition of black flies (Diptera: Simuliidae)

Although hematophagous black flies are well-known socioeconomic pests and vectors of disease agents, their associated bacteria are poorly known. A systematic analysis of the bacterial community associated with freshly emerged adult black flies of four North American species, using cultivation-independent molecular techniques, revealed 75 nonsingleton bacterial phylotypes. Although 17 cosmopolitan phylotypes were shared among host species, each fly species had a distinct bacterial profile. The bacterial composition, however, did not correlate strongly with the host phylogeny but differed between male and female flies of the same species from the same habitat, demonstrating that a group of insects have a gender-dependent bacterial community. In general, female flies harbor a less diverse bacterial community than do males. The anatomical locations of selected bacteria were revealed using fluorescence in situ hybridization. Understanding the physiological function of the associated bacterial community could provide clues for developing novel pest-management strategies.     

Three new mermithids (Nematoda) from Guatemalan blackflies (Diptera: Simuliidae)

Summary The following new species of Mermithidae (Nematoda) are described from Guatemalan blackflies: (a) Gastromermis cloacachilus from Gigantodax wrighti; (b) Isomernis vulvachila from Cnephia pacheco-lunai and (c) Mesomermis guatemalae from Simulium metallicum. All parasites were collected at Encuentros (Department of Totonicapan) in Guatemala. These are the first representatives of Gastromermis and Mesomermis from Central America and M. guatemalae represents the second mermithid species to be described from an American vector of Onchocerca volvulus, causal agent of river blindness. ac]19800728     

Ecology and speciation in African Blackflies (Diptera:Simuliidae)

The simuliid fauna of the Ethiopian region is notably isolated, only two of its species occurring elsewhere; the region has 124 described species, and others still undescribed. Simuliid larvae and pupae are adapted to attachment in moving water; adult females may disperse over considerable distances. This paper considers three examples of evident speciation in an ecological context:(1) speciation on afromontane 'islands' (2) the Simulium naevei group and the adaptive significance of the association between the early stages and freshwater crabs; (3) the S. damnosum complex, which includes the widespread vectors of human onchocerciasis. Maps show the distribution of species in these three groups.     

Distributional patterns of immature Simuliidae (Diptera) in northwestern North America

SUMMARY. 1. Major landscape features and hydrological parameters indicative of black fly species assemblages were examined at 101 stream sites in Alberta, northern British Columbia, the Yukon and Alaska during the summer. Forty-one black fly taxa were recorded at seventy- nine sites using qualitative sampling procedures. River sites lacking black flies had significantly higher conductivity, greater depth, shallower slope and were farther from the Pacific Ocean than sites with black flies.
2. Classification of sites by taxon occurrence using hierarchical cluster analysis suggested five groupings: A. Simulium tuberosum (Lundstrëm) complex + several taxa. B, S. venustum Saylverecundum Stone and Jamnback complexes + S, tuberosum complex; C. 5. arcticum Malloch complex + S. corbis Twinn complex; D, Gymnopais Stone/ Prosimulium Roubaud; and E. P. onychodactytum Dyar and Shannon complex + several taxa.
3. Multiple discriminant analysis (MDA) was used to predict group membership of the seventy-nine sites using nineteen environmental variables; 71% of the sites were classified correctly. MDA identified latitude and distance from stream source as important factors separating group D from other groups. Stream width and drainage basins entering the Arctic Oeean and Hudson Bay delineated group B. There was no clear separation among groups A. C or E. The presence of sibling species probably accounts for the overlap of black fly assemblages.
4. Our findings are briefly discussed in the context of stream classification systems, notably the river continuum concept.     

Patterns of polytene-chromosome replication in Simulium ornatipes (Diptera: Simuliidae)

Double labelling of Simulium ornatipes polytene chromosomes with H³- and C¹⁴-thymidine shows that chromosome synthesis follows three distinct phases viz. a short phase of initiation in puffs and interbands spreading to more condensed regions; a long continuous labelling phase, then a discontinuously labelled end phase as bands complete their replication in temporal sequence. Analysis of H³ labelling patterns indicates that while heterochromatic bands replicate there is no clear correlation between heterochromatic or C-banding regions and band replication time. The major characteristic governing band replication time appears to be band size and density. However, in some bands this relationship is modified, perhaps it is suggested, by DNA organisation influencing the efficiency of replicons. The existence of great variability in homologous band replication times, even within a chromosome pair, indicates that the control of band replication is highly autonomous. It is suggested that polymorphisms at the molecular level determine this variation. Replication time of active nucleolar organisers is very long in contrast to the short replication of condensed inactive organisers. This may reflect differential polytenisation of ribosomal DNA as a result of a developmental polymorphism, or the amplification of ribosomal DNA by active nucleolar organisers.     

Sex determination in Urosimulium stefanii Cont. (Diptera: Simuliidae)

Males of Urosimulium stefanii Cont., (1963) from various populations in Sardinia, differ from females by a long asynaptic region in one pair of salivary gland chromosomes. This asynaptic tract does not seem to be due to inversions but rather to large structural changes. In meioses of the male, a pair of chromosomes does not show interstitial chiasmata. It is suggested that this pair of chromosomes represents the sex chromosome pair. The evolutionary process has been discussed.     

Different life history strategies in lake-outlet blackflies (Diptera: Simuliidae)

The life histories of Simulium noelleri Fried. and S. truncatum Ldstr. were studied at a lake-outlet site in Finland. A detailed study was made of the second summer generation of both species and this consisted of a single, synchronized cohort in S. noelleri, and overlapped cohorts in S. truncatum. Larvae of the two species also show differences in their habitat preference: those of S. noelleri predominate on the sluice which marks the beginning of the river, and S. truncatum larvae just downstream from the sluice. In winter, the latter site was dominated by immature individuals of two other species, S. erythrocephalum de Geer and S. equinum L., and these were found downstream from the two ‘lake-outlet’ species during the summer. Adult females of S. noelleri are able to mature a first batch of eggs without taking a blood meal but those of S. truncatum need to feed on blood before eggs can be fully developed. The consequences of these different reproductive strategies on the ecology of individuals of the two species is discussed.     

Contribution to the blackfly fauna (Diptera: Simuliidae) of Iran

A collection of blackflies (Diptera: Simuliidae) from western Iran was examined, four species were recorded. Three new species are described: Tetisimulium iranicum sp. n., Wilhelmia lurestanica sp. n., and Crosskeyellum zagros sp. n. The presence of Tetisimulium coarctatum (Rubzov, 1940) in Iran is confirmed.     

The aquatic drift patterns of black flies (Diptera: Simuliidae)

Larval (5th-final instar) drift patterns of five species of black flies (Prosimulium mixtum, Stegopterna mutata, Simulium tuberosum FG, S. vittatum IIIL-1, and S. vittatum IS-7) were analyzed. The diel drift patterns were not species-specific, but consistently exhibited a marked increase after sunset, preceded by a period of minimal drift. The drift minimum generally occurred during or shortly after the period of maximum water temperature. Larvae showed significantly more nocturnal than diurnal drift. Pupal drift was attributed to accidental detachment from the substrate. Adult drift was over 90% diurnal and usually composed primarily of teneral individuals. Upstream larval movements of the S. vittatum and S. tuberosum complexes were each less than 6.5% of the total upstream and downstream larval movements. The proportion of parasitized larvae of the S. vittatum and S. tuberosum complexes was generally higher in the benthos than in the drift. Based in part on data included in a thesis submitted by the senior author to The Pennsylvania State University in partial fulfillment of the requirements for the Ph. D. degree.