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At least 613 records · Page 34Linked to original sources
PubMed2006

Disturbance, biological legacies and community development in stream mesocosms.

Disturbances reduce the biota in stream ecosystems, and leave biological legacies, including remnant species, which potentially influence post-disturbance community development but are poorly understood. We investigated whether three remnant species, the snail Radix peregra, the mayfly Serratella ignita and the freshwater shrimp Gammarus pulex, affected community development in mesocosms that mimicked disturbed habitat patches in streams. Following 21 days of colonisation, we found that the occurrence of legacy effects depended on the identity of the remnant species. Radix had the strongest effect. By bulldozing epilithon, the snails acted as ecological engineers that promoted settlement of filter feeders (Simuliidae) and invertebrate predators (especially Pentaneura and Aphelocheirus) and strongly deterred settlement of non-predatory chironomids (e.g. Heterotrissocladius and Microtendipes). Gammarus increased in density (by 665%) where remnant, probably through rapid reproduction. Baetis and Pentaneura were scarce, and Asellus absent, in remnant Gammarus treatments, as a consequence of interference and/or predation by the amphipods. In contrast, Serratella tolerated the colonisation of immigrant species and did not affect the structure of the developing benthic community. Despite the observed effects on the presence and abundance of benthos, remnant fauna had no significant effect on assemblage taxon richness, or that of any specific trophic group. The contrasting effects of remnant species on immigrant colonisation echoed differences in their life-history traits and foraging behaviours. Our results indicate that biota can generate spatial patchiness of epilithon and benthic invertebrates in stream ecosystems.

Amphipoda↗
PubMed1977

Man-biting species of Chrysops meigen, Culicoides latreille and Simulium latreille in Ethiopia, with discussion of their vector potentialities.

Human filariasis and its vectors are little known in Ethiopia. Wuchereia bancrofti is confined to the western lowlands and cannot be the aetiological agent of elephantiasis in the highlands. Onchocerca volvulus is widespread in the south-western highlands. Loa loa and Dipetalonema perstans are reported here for the first time and appear to be uncommon. Studies were conducted in 1973, mostly near Jimma in Kaffa Province, on potential vectors of all but the first of these parasites. Among Simuliidae, the only blackflies of apparent medical importance were S. woodi ethiopiense and a possibly new member of the S. damnosum complex. The former is less seasonal and much less numerous than the latter, but may be more widespread and important along smaller and higher streams. Onchocerca larvae were recovered from "damnosum", but not from the small number (46) of ethiopiense examined. In August, at the height of the rainy season, the biting-rate of ethiopiense at 1,710 m altitude on the Gilgil Ghibe river reached 9.5/man-hour at 10-1100 hours and about 12/man-hour at 14-1600 hours. At the same time and place, the attack of "damnosum" reached a midday climax of about 1,800/man-hour; this peak could be delayed or suppressed by rain. Another possibly anthropophilic blackfly, S. dentulosum, tended to become most common in December afer the rainy season had passed, but proved incompetent to bite man successfully. The only feasible loiasis vector found in Ethiopia was Chrysops streptobalius; however, this tabanid was not closely associated with man. Up to 34/man-day were caught in watermeadows by the Gojeb river (altitude 1,160 m) in October. Man-biting species of Ceratopogonidae in various parts of Ethiopia were Culicoides fulvithorax, C. grahamii, C. kingi and C. milnei. The first two of these were anthropophilic in lowlands, but apparently not so in highlands. C. milnei was extremely abundant biting man highlands. C. milnei was extremely abundant biting man and domestic animals both indoors and outdg cycle was irregular, usually displaying a succession of ill-define nocturnal peaks; sometimes it attacked in daylight. Up to 35,000 C. milnei per trap-night were caught in light traps. Most of the females entering light traps in a stable were already engorged with blood. It seemed very likely that C. milnei would prove to be of veterinary importance. No firm indication was obtained as to what may transmit D. perstans in Ethiopia.

Animals↗
PubMed1985

Characterization of New Jersey vesicular stomatitis virus isolates from horses and black flies during the 1982 outbreak in Colorado.

Vesicular stomatitis viruses isolated from horses, afflicted during the recent outbreak in the western United States, and from black flies (Simuliidae) were characterized with respect to the homology of their genomic RNAs and the mobility of their proteins in polyacrylamide gels. All the isolates were very similar, if not identical, with respect to these two parameters. When the black fly isolate was compared to other VSV isolates, this virus appeared to belong in the Hazelhurst subgroup of the New Jersey serotype of VSV. Since the other viruses in this division were obtained from infected swine, the natural host range of this subgroup has been extended to horses.

Animals↗
PubMed1989

The impact of methoxychlor treatment of the saskatchewan river system on artificial substrate populations of aquatic insects.

The impact of methoxychlor exposure on aquatic insects inhabiting artificial substrates was monitored at three downstream sites relative to an upstream untreated site of the North Saskatchewan River. Treatment impact was studied for selected species of Simuliidae (Diptera), Perlodidae (Plecoptera), Hydropsychidae (Trichoptera), Baetidae and Heptageniidae (Ephemeroptera). At sites subjected to methoxychlor exposure which were 21, 38, and 107 km from injection, population changes varied depending on species and distance from the injection point. Although populations of some species were not significantly affected by treatment at any downstream site (P > 0.05), others were significantly reduced at one or more of the sites (P < 0.05- P < 0.01). Nymphs of Stenonema terminatum (Walsh) and Baetis tricaudatus Dodds (Ephemeroptera) apparently recolonized after dislodgement due to methoxychlor exposure. Species are categorized on the basis of their responses to methoxychlor treatment. Factors which probably caused different treatment impacts among species are discussed.

Journal Article↗
PubMed1990

Impact of a massive crude oil spill on the invertebrate fauna of a Missouri Ozark stream.

The benthic macroinvertebrate fauna of Asher Creek, a 4th order stream with a base flow of 0.03 m(3)/s, was monitored on 11 occasions for 532 days following a 1.5 million liter domestic crude oil spill. Aquatic insects, crustaceans, segmented worms, roundworms, flatworms, snails, freshwater mussels and other benthic organisms in the oil impacted area were reduced to less than 0.1% of expected numbers at the first sampling period 25 days after the spill. Species diversity indices and the number of mayfly and stonefly taxa were less than the minimum values established for unpolluted Missouri streams for 11 months. The initial post-spill community was dominated by Chironomidae (midges), Simuliidae (blackflies) and Oligochaeta (segmented worms). Some species of Plecoptera (stoneflies), Ephemeroptera (mayflies) and Trichoptera (caddisflies) were absent from the fauna for as long as 9 months. The functional feeding groups of scrapers, filterers, gatherers, and predators initially decreased in relative abundance. Predators later increased in response to a rapidly expanding prey base. Shredders did not change in relative abundance throughout the recovery period. Oil was visually present in the stream riffle substrate for 453 days following the spill. Dissolved oxygen, pH and conductivity were not affected. The visible appearance of oil in the stream substrate was a simple predictor of the status of the benthic invertebrate community. Areas protected with surface skimming siphon dams were less severely impacted and recovered more rapidly than areas where the stream substrate was inundated with oil. The most apparent factors controlling the recovery were the total volume of water passing through the contaminated area and the occurrence of scouring flood.

Journal Article↗
PubMed2001

Biting behaviour and potential vector status of anthropophilic blackflies in a new focus of human onchocerciasis at Minaçu, central Brazil.

Monthly collections were made of man-biting female blackflies: Simulium auripellitum Enderlein, S. guianense Wise, S. minusculum Lutz and S. nigrimanum Macquart (Diptera: Simuliidae) from four catching stations in the newly discovered focus of human onchocerciasis at Minaçu (13 degrees 35 minutes S 48 degrees 18 minutes W), 300 km north of Brasília in Goiás State. These provided baseline data on biting habits, population density and seasonal prevalence during the year before completion of the Serra da Mesa hydroelectric dam on the Rio Tocantins near Minaçu, in a project investigating the effect of dam construction on onchocerciasis transmission in the area. All four simuliid species were most abundant during the dry season, and only bit in low numbers (S. auripellitum S. minusculum, S. nigrimanum) or were absent (S. guianense) in the wet season. Simulium minusculum was the predominant species at all catching stations, being particularly abundant by the large River Tocantins. The other three species were mainly associated with smaller rivers. In the dry season, biting rhythms of S. minusculum varied with catching site, while S. nigrimanum showed peaks of activity in early morning and during the afternoon. Experimental infection with Onchocerca volvulus (Leuckart) (Nematoda: Onchocercidae), from a human volunteer, showed that this parasite could develop fully in the four simuliid species, which are all considered to be potential vectors in the area.

Animals↗
PubMed1991

Arthropod faunal composition on Kentucky equine premises.

Thirty-nine arthropod species representing the families Muscidae, Chloropidae, Tabanidae, Simuliidae, Culicidae, and Ixodidae were collected from Kentucky equine premises using dry ice-baited canopy traps, light traps, water samples, tick drags, and animal inspections during late April to mid-October 1987 and 1988. Thirty-three species were collected from canopy traps, consisting of 74.3% muscid, 16.7% chloropid, 5.0% simuliid, 3.8% tabanid, and 0.2% culicid species. Light traps attracted eight culicid and water samples yielded three culicid species. One ixodid species was collected with drags, and animal inspections yielded two muscid and two ixodid species. Comparison of species assemblages among farms and across years using multivariate principal component analysis (PCA) yielded three distinct principal components, and PCA scores for each farm per year were correlated with biotic and abiotic environmental factors and management practices. The proximity to cattle herds was the best predictor of similarity in species assemblages among farms, reflecting the high percentage of muscid species collected. Poor management practices were partially responsible for proportionally larger populations of culicids, ixodids, and muscids on some farms.

Animal Husbandry↗
PubMed1996

Application of the ovarian oil injection and ovariolar separation techniques for age grading hematophagous Diptera.

The ovarian oil injection and ovariolar separation techniques were applied to determine the physiological age of species of the 3 dipteran families Culicidae, Simuliidae, and Tabanidae. The presence of a granular basal body (a granular area in the calyx wall within the ovariolar sheath) indicates at least 1 egg laying; that is, it can be used to separate parous from nulliparous females, which possess no granular basal body. In parous females, the number of ovipositions can be determined accurately by counting the number of dilatations in the diagnostic ovarioles. An egg sac, when present, indicates only the current egg laying. A diagram for age grading using the technique is presented and discussed.

Aging↗
PubMed1992

Environmental risk factors in endemic pemphigus foliaceus (Fogo selvagem). "The Cooperative Group on Fogo Selvagem Research".

Endemic pemphigus foliaceus or Fogo selvagem (FS) is an epidermal organ-specific autoimmune disease mediated by autoantibodies. Individuals at risk are peasants who live and work on farms located in the interior of certain endemic states of Brazil. This case-control study compares a group of 52 FS patients with 52 patients suffering from other dermatoses admitted and followed at the hospital for pemphigus (Hospital do Penfigo) in the city of Goiania, state of Goias. Patients and controls matched 1:1 by age, sex, and occupation were examined by two dermatologists at the time of admission and asked to respond to a prepared questionnaire. This questionnaire concerned current and past (1 and 5 years) exposure to environmental risk factors. The following risk factors were assessed: black fly bites, presence of rodents at home, exposure to cereal dust, exposure to fumes or dust released by tree and shrub removal, and exposure to insecticides. Relative risks were estimated from tabulated data by the odds ratio and tested for significance by the chi-square test. The 95% confidence interval for the odds ratio was also calculated for each of the risk factors. The only risk factor showing an odds ratio significantly different from one was exposure to simuliidae bites (odds ratio 4.7, p less than 0.001). This study reinforces the hypothesis that chronic exposure to black fly antigens may precipitate IgG4 antibody formation in predisposed individuals. These antibodies in turn may cross-react with epidermal antigens and cause acantholysis and the clinical expression of the disease known as FS.

Adolescent↗
PubMed1997

Phylogenetic relationships of the Culicomorpha inferred from 18S and 5.8S ribosomal DNA sequences. (Diptera:Nematocera).

We investigated the evolutionary origins of the mosquito family Culicidae by examination of 18S and 5.8S ribosomal gene sequence divergence. Phylogenetic analyses demonstrated that within the infraorder Culicomorpha, taxa in the families Corethrellidae, Chaoboridae and Culicidae formed a monophyletic group; there was support for a sister relationship between this lineage and a representative of the Chironomidae. A chaoborid midge was the closest relative of the mosquitoes. Taxa from four genera of mosquitoes formed a monophyletic group; lack of a spacer in the 5.8S gene was unique to members of the Culicidae. A member of the genus Anopheles formed the most basal lineage among the mosquitoes analysed. Phylogenetic relationships were unresolved for representatives in the families Dixidae, Simuliidae and Ceratopogonidae.

Animals↗
PubMed2003

Reduced seroprevalence of Kaposi's sarcoma-associated herpesvirus (KSHV), human herpesvirus 8 (HHV8), related to suppression of Anopheles density in Italy.

In two formerly malarious parts of Italy, age-related seroprevalence rates of Kaposi's sarcoma-associated herpesvirus [human herpesvirus 8 (KSHV/HHV8)] were determined from local blood donors and correlated with periods of vector control during anti-malaria campaigns. In Veneto, decreased KSHV/HHV8 seroprevalence in the 1951-1955 birth cohort coincides with the peak of DDT house-spraying. In Sardinia, where larviciding augmented indoor DDT-spraying, a significant drop of KSHV/HHV8 seroprevalence between 1945 and 1950 and 1951-1955 birth cohorts (P = 0.0046) coincides with suppression of the malaria vector Anopheles labranchiae Falleroni (Diptera: Culicidae). These results are consistent with age-related association between KSHV/HHV8 seroprevalence rates in native/resident populations and the density of malaria vectors in Veneto and Sardinia. This example supports our 'promoter arthropod' hypothesis on the role of haematophagous insects [putatively blackflies (Simuliidae), sandflies (Phlebotominae) and biting midges (Ceratopogonidae), as well as mosquitoes] when their bites induce hypersensitivity and immunosuppression, potentiate KSHV/HHV8 transmission via human saliva (when insect bite lesions are licked by another person whose saliva carries the virus) and may facilitate Kaposi's sarcoma.

Animals↗
PubMed2006

Spatial population genetic structure and limited dispersal in a Rocky Mountain alpine stream insect.

Using the mitochondrial cytochrome oxidase I (COI) gene, we assessed the phylogeographic structure of Prosimulium neomacropyga, a black fly (Simuliidae) whose distribution in the US Southern Rockies ecoregion is limited to alpine tundra streams. Given high habitat specificity, lack of hydrological connection between streams, and a terrestrial environment restrictive to insect flight, we hypothesized limited gene flow. A spatially nested sampling design showed that grouping populations according to high-elevation 'islands' of alpine tundra (which typically include headwater streams of > 1 watershed) explained a significant proportion of genetic variation while grouping streams according to major watershed (across islands) did not. Nested clade analysis and isolation-by-distance (IBD) relationships further implicated limited ongoing gene flow within but not among the isolated alpine islands. IBD was strong among five streams within an individual island using each of four alternative models of pairwise landscape connectivity for flying insects. Results of all landscape models were positively correlated, suggesting that straight-line distance is an acceptable surrogate for presumably more biologically meaningful connectivity measures in this system. IBD was significantly weaker across the entire study area, comprised of three separate islands. Overall, population structure was significant with F(ST) = 0.38, suggesting limited dispersal across a small spatial extent.

Animals↗
PubMed2004

Allomonal effect of breath contributes to differential attractiveness of humans to the African malaria vector Anopheles gambiae.

BACKGROUND: Removal of exhaled air from total body emanations or artificially standardising carbon dioxide (CO2) outputs has previously been shown to eliminate differential attractiveness of humans to certain blackfly (Simuliidae) and mosquito (Culicidae) species. Whether or not breath contributes to between-person differences in relative attractiveness to the highly anthropophilic malaria vector Anopheles gambiae sensu stricto remains unknown and was the focus of the present study. METHODS: The contribution to and possible interaction of breath (BR) and body odours (BO) in the attraction of An. gambiae s.s. to humans was investigated by conducting dual choice tests using a recently developed olfactometer. Either one or two human subjects were used as bait. The single person experiments compared the attractiveness of a person's BR versus that person's BO or a control (empty tent with no odour). His BO and total emanations (TE = BR+BO) were also compared with a control. The two-person experiments compared the relative attractiveness of their TE, BO or BR, and the TE of each person against the BO of the other. RESULTS: Experiments with one human subject (P1) as bait found that his BO and TE collected more mosquitoes than the control (P = 0.005 and P < 0.001, respectively), as did his BO and the control versus his BR (P < 0.001 and P = 0.034, respectively). The TE of P1 attracted more mosquitoes than that of another person designated P8 (P < 0.021), whereas the BR of P8 attracted more mosquitoes than the BR of P1 (P = 0.001). The attractiveness of the BO of P1 versus the BO of P8 did not differ (P = 0.346). The BO from either individual was consistently more attractive than the TE from the other (P < 0.001). CONCLUSIONS: We demonstrated for the first time that human breath, although known to contain semiochemicals that elicit behavioural and/or electrophysiological responses (CO2, ammonia, fatty acids) in An. gambiae also contains one or more constituents with allomonal (~repellent) properties, which inhibit attraction and may serve as an important contributor to between-person differences in the relative attractiveness of humans to this important malaria vector.

Journal Article↗
PubMed2000

The taxonomy of Brazilian insects vectors of transmissible diseases (1900-2000)--then and now.

A brief historical overview is given of the most relevant taxonomic studies of insect groups vectors of transmissible diseases in Brazil, from the "heroic" times of the foundation of the Instituto Oswaldo Cruz in Rio de Janeiro up to the present. The following orders are considered: Phthiraptera (Anoplura, Amblycera and Ischnocera), Hemiptera (Reduviidae: Triatominae), Siphonaptera and Diptera (Culicidae, Ceratopogonidae, Psychodidae: Phlebotominae, Simuliidae, Tabanidae, Chloropidae and Muscidae). The most important Brazilian collections of each group are cited.

Academies and Institutes↗
PubMed2005

Macroinvertebrate community response to pulse exposure with the insecticide lambda-cyhalothrin using in-stream mesocosms.

Pesticides are constantly being applied to agricultural catchments, but little is known about their impact on aquatic biota during natural exposure. In the present study, the impact of the pyrethroid lambda-cyhalothrin was studied in an in-stream mesocosm setup. Twice during the summer of 2002, the natural macroinvertebrate community was exposed in situ to a 30-min pulse of lambda-cyhalothrin. Pyrethroid doses were released through a modified drip set with nominal concentrations of 0.10, 1.00, and 10.0 microg L(-1) during the first exposure and 0.05, 0.50, and 5.00 microg L(-1) in the second exposure. Before, during, and after exposure, drifting macroinvertebrates were caught in nets. Quantitative benthic samples were taken both before and on two occasions after exposure. Macroinvertebrate drift increased immediately after the pulse exposure, with total drift being significantly higher at all concentrations. Gammarus pulex, various Ephemeroptera, Leuctra sp., and Simuliidae were some of the taxa showing the most pronounced drift response. Structural change in the community was found only at 5.00 and 10.0 microg L(-1), and recovery occurred within approximately two weeks. The present study may be valuable in assessing extrapolations based on laboratory results as well as in evaluating pyrethroid impact on natural freshwater environments.

Animals↗
PubMedDate not supplied

Trichomycetes living in the guts of aquatic insects of Misiones and Tierra del Fuego, Argentina.

Fourteen species of Trichomycetes living in the guts of aquatic insects are reported from two provinces of Argentina, Misiones and Tierra del Fuego. Twelve of the species belong to the Harpellales and two are Amoebidiales. Five harpellid species are reported from Misiones in the extreme northeast of the country (Genistellospora homothallica, Harpella tica, Smittium culisetae, Smittium sp., Stachylina sp.) and seven are from Tierra del Fuego, the southern tip of South America (H. meridianalis, Glotzia sp., S. culicis, S. cellaspora, S. imitatum, Stachylina minima, Penella simulii). Insect hosts all were immature stages of Culicidae, Simuliidae, Chironomidae, Ceratopogonidae (Insecta: Diptera), and Ephemeroptera and Plecoptera. The lower diversity of Trichomycetes found at Misiones, which has a subtropical climate and rainforest vegetation, was due possibly to the warmer temperatures of the water (15-24 C), compared to the colder streams of Tierra del Fuego (9-15 C), with forests and steppes as typical vegetation.

Animals↗
PubMed2002

A combined microcosm and field approach to evaluate the aquatic toxicity of azinphosmethyl to stream communities.

We evaluated the potential effects of the organophosphate insecticide azinphosmethyl (AZP) in a combined microcosm and field approach. The upper regions of the Lourens River, South Africa, are free of contamination (control site), whereas the subsequent stretches flowing through a 400-ha orchard area receive transient insecticide pollution (e.g.. 0.82 microg/L AZP, 344 microg/kg chlorpyrifos) following spray drift and runoff (contaminated site). Stones taken from the control site were transferred to outdoor microcosms (1.5 x 0.2 x 0.2 m), providing 12 core species and approximately 350 individuals per microcosm. Microcosms were contaminated for 1 h with AZP (control, 0.2, 1, 5, and 20 microg/L; three replicates each), and acute effects on survival were evaluated 6 d following exposure. The two strongest treatments (measured concentrations: 19.2 +/- 1.0 and 4.9 +/- 0.3 microg/L, respectively) resulted in a significantly (analysis of variance) reduced invertebrate density, attributed mainly to various insect taxa, such as Demoreptus sp., Castanophlebia sp., Simuliidae, and Chironomidae. In contrast, Aeshna sp., Dugesia sp., Ceratopogonidae, and Cheumatopsyche sp. were unaffected. In parallel, we conducted a quantitative macroinvertebrate survey at the control site and the contaminated site of the Lourens River after the seasonal pesticide application period. The two sites contained a similar number of species but differed considerably in their species composition and abundances. Five of the eight species that were affected by AZP in the microcosm study occurred in the field at significantly lower densities at the contaminated than at the control site or were absent at the contaminated site. All of the four species that were unaffected in the microcosm occurred at significantly higher densities at the contaminated field site. Only 3 of the 12 species reacted differently in the microcosm and the field study. We conclude that microcosm studies employing a field-relevant design could be linked successfully to field studies and our results suggest that transient pesticide contamination affects the aquatic communities of the Lourens River.

Animals↗
PubMed1976

[Incidence and damages inflicted by simuliid flies in the GDR district of Schwerin].

Systematic faunal studies in the district Schwerin showed at the present time there are 3 more or less damage-biotopes existing in the districts of Perleberg, Ludwigslust and Parchim; 5 river sources can be considered as potential sources, 5 are temporary and 2 are ephemeral whilst in 3 further areas environmental influences such as effluent impairs the flow of the river and the developmental stages of Simuliidae were not observed.--The following species were found: Boophthora erythrocephala, Wilhelmia salopiensis, Wilhelmia equina, Odagmia ornata, Eusimulium aureum and Eusimulium lundstroemi.--The damage statistics covering the period 1966--1971 showed in the district of Schwerin, due to Simuliid attacks, 38 cattle died, 170 were seriously ill; in 1967 5 horses were seriously ill; in 1971, 3 pigs died and 27 were seriously ill.--The symptoms were manifested by pathological petechiae, scabs and oedema, also by insufficiency of the heart and circulatory system, diminished performance and growth disturbance. In severe cases heart and circulation failure occurred, paresis, coma and death followed.--The real economic significance of the Simuliid attacks rest with its strong and prolonged distrubance in young animals, as well as in pronounced irreparable diminished performance in diseased dairy cattle.

Animals↗