Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Simuliidae”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33Linked to original sources
PubMed1995

Oviposition aggregation pheromone in the Simulium damnosum complex.

Communal oviposition by the Simulium damnosum complex of Afrotropical blackflies (Diptera: Simuliidae) was investigated under controlled laboratory conditions, using wild-caught flies in Sierra Leone. Volatile compounds emitted by Simulium eggs were trapped using a closed collection system, and their attractiveness to gravid flies was tested in a two-choice behavioural bioassay. Significantly more female blackflies oviposited on substrates baited with freshly laid eggs (100% chose the baited substrate), or with the volatiles collected from freshly laid eggs (85% chose the baited substrate), in preference to the relevant control substrates. Substrates baited with volatiles from 12-h-old eggs were not significantly more attractive than controls (only 31% chose the baited substrates; P = 0.33). Gas chromatographic analysis of the egg volatiles consistently showed two peaks emanating from fresh eggs, but significantly lower amounts from 12-h-old eggs (P < 0.05). A novel system for collecting the volatiles from this and other blackfly species, as they laid eggs on a substrate in flowing water, is described. Volatiles collected using this method showed identical gas chromatographic profiles to those of fresh eggs alone, indicating that the flies themselves produced no other volatile chemical signals during oviposition. Evidently communal oviposition by S. damnosum s.l. was mediated by a pheromone emanating from fresh eggs. The role of pheromone-mediated egg aggregation in blackfly ecology is discussed, and its possible manipulation is considered.

Animals↗
PubMed2005

Field and laboratory studies on water conditions affecting the potency of VectoBac (Bacillus thuringiensis serotype H-14) against larvae of the blackfly, Simulium damnosum.

River water conditions that might influence the efficacy of VectoBac, a formulation of the microbial insecticide Bacillus thuringiensis H-14 Berliner against Simulium damnosum sensu lato Theobald (Diptera: Simuliidae) larvae were investigated. A standard formulation was assayed 130 times over 15 months using a mini-gutter system at a field station beside the River Pra in Ghana. The lethal concentration (LC) values, river temperature, conductivity, turbidity and pH were analysed using univariate and multivariate statistics to identify which of these parameters influenced its performance. River temperature, conductivity and turbidity (in that order) were identified as having direct effects on the potency of VectoBac. Water temperature and conductivity were negatively correlated, whereas turbidity and pH were positively correlated with LC values. Analyses of river water samples revealed that despite observed differences in total solids, sodium and potassium cations and chloride concentrations, all the parameters measured did not differ significantly between wet and dry seasons. A simple method for rearing S. damnosum s.l. in the laboratory was then adopted to study the effect of conductivity on potency of VectoBac under controlled conditions. Increasing the conductivity of the water medium up to 3,000 microS enhanced potency by about 42%, whereas increasing that of the insecticide alone raised it by 37%. The results obtained suggest that for effective use of VectoBac for blackfly control in West Africa, river temperature, conductivity and turbidity should be taken into consideration, perhaps by only selecting rivers with optimal conditions for treatment. The laboratory-based system developed for assaying the product overcomes the vagaries associated with field conditions and also the demand for huge logistic requirements of the mini-gutter system, which has to be sited near rivers.

Animals↗
PubMed2006

Transmission of Onchocerca volvulus and prospects for the elimination of its vector, the blackfly Simulium neavei in the Mpamba-Nkusi focus in Western Uganda.

The transmission of Onchocerca volvulus Leuckart (Spirudida: Onchocercidae) and the prospects of Simulium neavei Roubaud (Diptera: Simuliidae) vector elimination through ground larviciding were investigated in the Mpamba-Nkusi focus, western Uganda. Transmission levels and the initiated vector elimination activities were assessed to supplement the ongoing ivermectin mass distribution programme. Searches for breeding sites, adult fly catches, dissection of flies, river treatment with temephos (Abate) and a review of annual ivermectin treatment data were conducted. High levels of crab infestation with S. neavei sensu stricto immature stages were recorded; 57.9% and 100% for the Mpamba and Nyabugando river systems, respectively. The mean numbers of larvae/pupae per crab were 3.6 +/- 0.5 in the Mpamba and 20.6 +/- 1.8 in the Nyabugando systems. Pre-intervention mean biting densities were 39 and 32 flies/(man day) in 2001 and 2002, respectively, and an annual biting rate in 2001 of > 14 000. The bimodal biting pattern of S. neavei s.s. consisted of two peaks; one in the morning (09.00-10.00 hours) and one in the afternoon (14.00-15.00 hours) with a mid-day lull in biting. The infection/infective rates were 13.3%/2.8% and 16.6%/2.9% in the dissected parous flies from the Mpamba and Nyabugando river systems, respectively. Out of approximately 1000 parous flies, 129 and 109 were found to be harbouring infective larvae of Onchocerca volvulus in their heads from the Mpamba and Nyabugando river systems, respectively. In spite of the > 10 years of ivermectin treatment, at a mean coverage of 71.3%, infection remained relatively high. Ground larviciding with temephos (Abate) initiated in June and October 2002 had a significant impact. In the Mpamba river system there was a significant (P < 0.001) reduction in positive crabs from 57.9% in 2001 to 0.06% in 2003 and a decrease in the mean number of larvae/pupae per crab from 3.6 +/- 0.5 in 2001 to 0.0007 +/- 0.0001 (P < 0.002) in 2003. Similarly, in the Nyabugando river system, a significant (P < 0.001) reduction in crab infestation from 100% in 2001 to 0.06% in 2003 and a decrease in the mean number of larvae/pupae per crab from 20.6 +/- 1.8 in 2001 to 0.06 +/- 0.03 in 2003. Drastic reductions were observed in the mean number of biting flies from 3 flies/h in 2001 to 0 flies/h in 2003 and the annual biting rates fell from 14,235 flies/year in 2001 to only 730 flies/year in 2003. These data suggest that substantial progress towards the goal of S. neavei s.s. vector elimination has been made and this will enhance the ongoing ivermectin treatment in this isolated focus.

Animals↗
PubMed2006

Guide to blackflies of the Simulium damnosum complex in eastern and southern Africa.

At least 26 members of the Simulium damnosum Theobald complex (Diptera: Simuliidae) are known from eastern Africa, most of which are assumed to be non-anthropophilic and some are restricted to small areas of endemicity. Their discovery was based on polytene chromosome inversion polymorphisms and since then they have been cited as cytological entities, but, in many cases, with inadequate descriptions (e.g. without illustrations of the chromosomes). The present distribution, taxonomy and vector identity have been re-evaluated during the last decade in conjunction with ongoing onchocerciasis control programmes. Here, a summary of the relevant data is presented, integrating results of cytotaxonomic, morphotaxonomic and molecular investigations into a guide that provides a comprehensive system of identification for the cytoforms 'Kagera', 'Kasyabone', 'Kibwezi', 'Kisiwani', 'Kisiwani E', 'Kulfo', 'Linthipe', 'Mombo', 'Mutonga', 'Njombe', 'Nkusi', 'Nkusi SA', 'Nkusi SW', 'Nyika', 'Pienaars', 'Sanje', 'Sebwe', 'Turiani', Simulium damnosum sensu stricto, Simulium kaffaense Hadis et al., Simulium kilibanum Gouteux, Simulium kipengere Krueger, Simulium latipollex (Enderlein), Simulium pandanophilum Krüger, Nurmi & Garms, Simulium plumbeum Krueger, Simulium thyolense Vajime et al. and for five newly recognized molecular forms of 'Nkusi' and S. kilibanum. All taxa except S. pandanophilum are assigned to one of five subcomplexes (damnosum, Ketaketa, Kibwezi, Sanje, squamosum) within the S. damnosum complex. The guide encompasses anthropophilic and non-anthropophilic segregates for the whole of eastern and southern Africa, and is not restricted to larval chromosome criteria; in many cases it also allows the typing of adult flies.

Africa, Eastern↗
PubMed2006

Revision of the Ketaketa subcomplex of blackflies of the Simulium damnosum complex.

A revision of the taxonomy of the Ketaketa subcomplex of the Simulium damnosum Theobald complex (Diptera: Simuliidae) is presented including new material from Tanzania, Malawi and South Africa. The cytotaxonomy, morphology and molecular identity of known and new taxa are described. The Ketaketa subcomplex is cytotaxonomically defined by the paracentric inversion 1L-7. We recognize three sibling species, namely Simulium latipollex (Enderlein), Simulium plumbeum Krueger, sp.n. and Simulium kipengere Krueger, sp.n., the latter comprising three cytoforms: 'Typical', 'Linthipe' and 'Mombo'. The cytoforms 'Mwamphanzi', 'Ketaketa' and 'Hammerkopi' are synonymized with S. plumbeum. Identification keys are provided on the basis of chromosomal and morphological characters. In view of their potential role as vectors of human onchocerciasis (river blindness) we also discuss the possible medical importance of the different cytoforms and their geographical distribution.

Animals↗
PubMed2000

Simulium spp. control program in Rio Grande do Sul, Brazil.

Insects of the Simuliidae family have been the object of control in Rio Grande do Sul since the 70s. Their constant attacks became a social-economical problem as well as a problem of Public Health, with serious consequences to men and to the economy of the areas in which the insects develop. At first, the control was done with a chemical larvicide Themephos ABATE 500 E, but an imperfect measuring of outflow to determine the quantity of the product made Simulium spp. resistant to it. From 1983 on, following a study of a new method for the outflow measuring, we started to use a biological larvicide Bacillus thuringiensis serovar israelensis based. The biological control uses the new method in 36.4% of the state area, assisting about 3,500,000 inhabitants.

Animals↗
PubMedDate not supplied

Trichomycete insect symbionts in Great Smoky Mountains National Park and vicinity.

Collections of trichomycete symbionts of larval aquatic insects in Great Smoky Mountains National Park and vicinity in the southern Appalachian region of the USA resulted in finding many taxa of Harpellales, including an unusual new monotypic genus, Barbatospora ambicaudata in Simuliidae, and five new species in Thaumaleidae or Chironomidae, Harpellomyces montanus, Smittium lentaquaticum, Sm. minutisporum, Stachylina gravicaudata and St. stenospora. In addition a new species of Amoebidium (Amoebidiales), A. appalachense, attached to the anal tubules of bloodworms (Chironomidae) is described. Axenic cultures of three of the new taxa were obtained, plus Sm. culisetae. Fourteen identified species representing 13 genera of previously known Harpellales are recorded from Plecoptera, Ephemeroptera and Diptera, as well as a new Dipteran host record for an unidentified harpellid that was found in a Blephariceridae. Also identified were Paramoebidium corpulentum and many undetermined species of Paramoebidium (Amoebidiales) from four orders of aquatic insect larvae. The occurrence of an Enterobryus species in Diplopoda and another Eccrinales from an aquatic beetle is noted. Amoebidiales,

Animals↗
PubMed1984

Morphogenesis of larval Onchocerca volvulus in the Panamanian black fly, Simulium quadrivittatum.

Simulium quadrivittatum Loew (Diptera: Simuliidae), a man-biting black fly, was shown, for the first time, to be capable of supporting development of Onchocerca volvulus Leuckart (Nematoda: Filarioidea) from microfilariae to third-stage (infective) larvae. The black flies were collected in Chiriqui Province, Panama and transported alive to Guatemala, where they were allowed to feed on a human subject infected with O. volvulus. Samples of these flies were dissected over an 11-day period to assess morphogenesis of the parasite. Vigorously motile microfilariae were recovered from the mid-gut during the first 24 hours postfeeding; second-stage larvae were found in the thoracic musculature on day 4; and fully developed third-stage larvae were obtained from the cephalic capsule by day 10. This rate of larval development is similar to that observed in Guatemalan S. ochraceum. Onchocerciasis is not known to occur in Panama. The results of the present study direct attention to a potential public health hazard there and possibly elsewhere in Central America.

Animals↗
PubMed1959

Methods of water-flow measurement applicable to Simulium control.

For the effective control of the Simuliidae-and for a variety of other public health activities-it is important to determine with reasonable accuracy the rate and volume of flow of the rivers and streams which they infest. The field worker requires for this purpose an instrument that is at once cheap and easy to handle. The author of this paper reviews a number of means and instruments available for water-flow measurement and devotes special attention to the Pitot tube, which is well suited to the conditions encountered in Simulium control schemes.

Animals↗
PubMed1962

Entomological aspects of African onchocerciasis and observations on Simulium in the Sudan.

Following a review of the literature on Simuliidae, relevant to the African scene, since 1955, the authors present observations made on Simulium damnosum at Mvolo, Equatoria, and along the Damer reach of the Nile, in the Sudan and consider these in relation to the economic importance of this species and the possibilities for control of the fly and of onchocerciasis transmitted by it.Meta-diethyltoluamide has been shown to be an effective repellent against this species, and the authors suggest that this or some other modern insect repellent might usefully be made available locally.It is suggested that the full life-cycle of S. damnosum in this area needs to be worked out, and a study made of the long-term effects of DDT larviciding on the flora and fauna of a typical river. A procedure for larviciding is recommended. Attention is drawn to the possibility of achieving natural control.

Animals↗
PubMed2003

[Morphological diversity of centromere regions in polytene chromosomes of blackflies (Diptera, Simulidae)].

Karyotypes of more than 120 species of 33 genera of the Palearctic blackflies (Simuliidae) were studied on squashed acetoorcein stained preparations of salivary gland polytene chromosomes in larvae. In the course of evolution of the family, a significant complication was noticed in the morphology of centromere regions of polytene chromosomes. In plesiomorphic species, centromeres are not pronounced morphologically and the general picture does not differ from that of other bands and interbands of the polytene chromosome. In species with apomorphic characters, a distinct precentromeric heterochromatin appears, whose manifestation is responsible for morphological diversity of centromere zones in polytene chromosomes. They are represented either by conspicuous slightly thickened heterochromatic bands or by large amplified blocks of heterochromatin or puff-like structure, being considerably extended as a result of despiralization of precentromeric heterochromatin. There are species, which more commonly lack chromocentre and their chromosomes are separated. Some other species have ectopic contacts between pricentromeric heterochromatin. In some species, this heterochromatin is organized as a compact chromocentre. This has been found only in representatives of southern latitudes, most frequently in evolutionarily young species with narrow specialization.

Animals↗
PubMed1989

[Simuliosis--dermatosis caused by black flies. A forgotten epizootic infection?].

Bites of black flies (Simuliidae) can produce strong ictus reactions in humans, associated with rubor, central hemorrhages, swellings, hemorrhagic erythema and edema. This can be accompanied by impairment of the general state of health. Suitable weather conditions may result in mass multiplication of the species. As a consequence man and animals may be seriously molested. Starting from strong ictus reactions of a patient the case report and therapy of simuliosis (simuliotoxicosis) as well as some points of the biology of black flies are described.

Adult↗
PubMed1987

Simulium dermatitis in man--clinical and biological features in South Africa. A case report.

Simulium bite reaction is described; the lesions were present mainly on the lower legs as palpable purpura, which persisted for 2 weeks with marked oedema and considerable discomfort. Simuliids are tiny bloodsucking flies, popularly known as blackflies or buffalo flies, belonging to the dipterous family Simuliidae. They occur world-wide, breed in fast-flowing streams, and are a major animal pest. This is the first description of blackfly bites in man in the South African literature.

Adult↗
PubMed1993

[Factors affecting the efficacy of 2 growth regulator compounds, OMS 3010 (phenoxycarb) and OMS 3019 (ethoxypyridine), on larvae of the Simulium damnosum complex].

Two insect growth regulators (IGR'S) acting as juvenile hormone analogs (JHA'S), OMS 3010 (phenoxycarb) and OMS 3019 (ethoxypyridine) were selected after a screening of several compounds proposed by industry on black fly larvae of the Simulium damnosum complex (Diptera: Simuliidae) the vector of onchocerciasis in West Africa. Bioassays were designed to study two parameters: larval age and exposure time. The results showed that these compounds are more efficient on old larvae (6th and 7th instars) than young larvae (3rd, 4th and 5th instars). However, exposure time seems essential. The black fly larvae live in fast running water courses. Thus, it is difficult to insure a prolonged exposure time in natural conditions. Though being active on black fly larvae, three factors are limiting the prospects for operational use of these two compounds: high dosages, limited effectiveness on young instar larvae and exposure time.

Animals↗
PubMed1999

Larval antennal sensilla in water-living insects.

An overview of larval antennal sensilla in hemimetabolous and holometabolous water-living insects is given by updating current knowledge on the fine structure of these sensory systems. In the absence of successful electrophysiological studies, the possible function of sensilla is deduced from their architecture. Various kinds of sensilla are described in hemimetabolous insects, such as Ephemeroptera, Odonata, and Plecoptera, and holometabolous insects, such as Diptera Nematocera (Culicidae, Simuliidae, Psychodidae, Chaoboridae) and Trichoptera. Their possible function in responding to stimuli from the freshwater environment is illustrated and discussed. The importance of sensilla as taxonomic and phylogenetic traits is reported in Baetidae (Ephemeroptera) and in Diptera Nematocera. Some homologies outlined in Diptera Nematocera give evidence of a link between species, such as Chaoboridae and Psychodidae, whose antennae are highly modified, prehensile in the former and very reduced in the latter. Particular features, such as cuticle without pores in chemosensory sensilla and naked perikarya, are so far found exclusively in some water-living arthropods, thus reflecting a possible adaptation to the aquatic habitat. The structure of sensilla and chloride cells, which have a similar external morphology, is presented and discussed in various insect groups, considering the possible derivation of the chloride cells from sensilla.

Animals↗
PubMed1996

Assessing the effects of a C14-15 linear alcohol ethoxylate surfactant in stream mesocosms.

Fish, benthic macroinvertebrate, and plant responses to 30-day exposures of C14-15 linear alcohol ethoxylate surfactant with an average of 7 mol of ethylene oxide (LAE) were measured in flowthrough stream mesocosms. Replicate stream mesocosms were treated in two experiments with concentrations of LAE ranging from 80 to 550 microg/liter. Macroinvertebrates were relatively insensitive with the exception of Simuliidae density which was significantly affected at 160 microg/liter. Fathead minnow (Pimephales promelas R.) reproduction was significantly reduced at >280 microg/liter and larval survival decreased significantly at 330 microg/liter. Growth and mortality of bluegill sunfish (Lepomis macrochirus L.) were not affected at the highest exposure concentration of 330 microg/liter in the first experiment. No ecologically significant effects were observed for vascular aquatic plants or periphyton. The laboratory and stream mesocosm results were similar with NOECs ranging between 80 and 550 microg/liter surfactant. The study provided data for an improved risk assessment of this nonionic surfactant, by reducing the uncertainty associated with extrapolation from laboratory data.

Animals↗
PubMed1999

Histopathological effects of tannic acid on the midgut epithelium of some aquatic Diptera larvae.

The impact of tannins on larval Nematocera was investigated by an extensive survey of the relative toxicity of tannic acid in Diptera larvae representative of mosquito communities from alpine hydrosystems (Culicidae, Chaoboridae, Chironomidae, and Simuliidae) together with a nonindigenous vector competent Culicidae species. Bioassays indicate that exposure to tannic acid at concentrations from 0.25 to 4 mM is deleterious for Culex pipiens, Simulium variegatum, and Chironomus annularius, but not for Aedes, Anopheles, Culiseta, and Chaoborus species. Histopathological observations reveal that, among the target organs of tannic acid, mainly the midgut epithelium is affected by treatment. However, the extent of degeneration varies according to the taxon, the duration of the treatment, and the concentrations assayed. The vulnerability of epithelial cells differs among cell types, clear cells of the anterior midgut showing symptoms of intoxication before dark cells of the posterior midgut. The toxic effects of tannic acid are discussed, particularly in comparison to those of insecticidal bacteria, in order to evaluate the potential for use of tannins in the regulation of larval populations of dipteran pests.

Animals↗
PubMed1999

Impact of bacillus thuringiensis var. israelensis On larvae of chironomus thummi thummi and psectrocladius psilopterus (Diptera: chironomidae)

Chironomid larvae, especially species of the subfamily Chironominae, are known to be sensitive to the mosquitocidal bacterium Bacillus thuringiensis var. israelensis (B.t.i.). In this study, bioassays and electron microscopic investigations were carried out with third- and fourth-instar larvae of Chironomus thummi thummi Kieffer (subfamily Chironominae) and Psectrocladius psilopterus Kieffer (subfamily Orthocladiinae) in order to study the sensitivity of species belonging to different chironomid subfamilies. Both species showed susceptibility to increased B.t.i. concentrations, with LC50 values (24 h) ranging from about 40- to 60-fold the LC50 for Aedes aegypti (LC50 (24 h) is 0.77 mg/L for C. thummi thummi and 1.17 mg/L for P. psilopterus). C. thummi thummi was shown to be twice as sensitive as P. psilopterus. Ultrastructural investigations of the anterior midgut showed cellular alterations in larvae exposed to a high B.t.i. concentration (2.8 mg/L, about 50-fold the LC50 for A. aegypti), such as swelling of mitochondria, dilatation of intercellular spaces and basal labyrinth, fenestration or disorganization of the Golgi complex, concentric arrangement of rough endoplasmic reticulum, and an increase of lysosomes and myelin figures. Electron-lucent regions within the cell, cell protrusion, and, in some cases, swelling or lysis of cells were further effects observed in treated animals. Most effects were found in both species, though they seemed to be more severe in C. thummi thummi. The alterations coincide with those known from target organisms (Culicidae, Simuliidae). This study shows that there is a difference in sensitivity to B.t.i. between chironomid species from different subfamilies and that the susceptibility of chironomid larvae to the bacterial toxins is due to damage of the midgut epithelium as it is in target organisms. Copyright 1999 Academic Press.

Journal Article↗