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At least 631 records · Page 35Linked to original sources
PubMed2003

Feeding ecology of Cobitis paludica and Cobitis calderoni in Central Spain.

In total, 253 specimens of Cobitis paludica and 163 Cobitis calderoni were collected in the Lozoya River (Madrid, Spain) in April, May, July, September and December 1990. Both species showed high percentages of empty guts in all months. C. paludica fed mainly on detritus and invertebrates while Cobitis calderoni fed on invertebrates and unicellular algae. Preferred prey items were the larvae of Dipterans (Chironomidae, Simuliidae) and micro crustaceans, with Ephemeroptera (Caenis) in summer. Cobitis calderoni fed on the most abundant prey except in April and July, when it selected invertebrates. C. paludica selected invertebrates throughout all the months. Diet overlapping (Horn's Index) was complete except in September, when the abundance of invertebrates in both diets was similar. For the remaining months, food type (invertebrates, unicellular algae and detritus) abundance differed, minimizing the interspecific competition.

Animals↗
PubMed1999

[The influence of diptera on the domestic animals].

The Diptera attacked domestic animals in Poland are: Simuliidae, Culicidae, Tabanidae, Gasterophilidae, Hypoder-matidae and Muscidae. The insect assail the crazing animals, mostly during sunny day dna at close of day. Lack of effective repelents and also difficulties with their usage, makes it impossible to complete extermination of parasitic insects in the environment. It is posible to effectively fight against Hypoderma bovis and Gasterophilus spp.

Animals↗
PubMed1978

Arbovirus isolations from mosquitoes in South Slovakia.

In the years 1973 and 1975 mosquitoes and some other Diptera (Tabanidae, Simuliidae, Hippoboscidae) were tested for virus. 13,924 mosquitoes, 75 horseflies and 60 blackflies were processed in 1973. Five strains of Tahyna virus were isolated from mosquito species Aedes vexans. 3,378 mosquitoes and 12 sheep keds were tested for virus in 1975. Twelve strains of Calovo virus were isolated from Anopheles maculipennis and one strain of Tahyna virus was obtained from Aedes vexans mosquitoes.

Aedes↗
PubMedDate not supplied

[Leucocytozoa (Haemosporidia, Leucocytozoidae) as biological markers in population research on birds].

Data on the infection of birds with Leucocytozoon were suggested to be used for investigation of the structure of hosts' populations in the regions isolated by ecological barriers where breeding places of bloodsucking flies (Simuliidae) are absent. Conducted parasitological investigations have shown that when migrating through the Courland Spit birds of more northern populations extensively infected with Leucocytozoon either do not merge with local populations of chaffinch, willow wren and icterine warbler or their portion is quite negligible. This phenomenon is indicative of the relative stability of the above Courland Spit populations of birds.

Animals↗
PubMed1983

Incidence and some ecological aspects of avian trypanosomes in Czechoslovakia.

A total of 1 874 birds belonging to 99 species was investigated on the presence of trypanosomes in Czechoslovakia, using the method of blood smears and cultivation from peripheral blood (PEN method) and autopsies with subsequent cultivation from the bone marrow. Apart from a single finding in owls, the trypanosomes were detected only in passerines which represent the majority of birds investigated (1 518 specimens belonging to 66 species). Except for sparrows, in which trypanosomes were present very rarely, they were abundant practically in all bird families represented by a sufficient number of specimens. Autopsies showed that trypanosomes occurred on the average in 23.6% of passerines. Throughout the year their presence in peripheral blood of birds ranged from a peak in June (29% of positive passerines after PEN method) to their absence in the winter months. There were differences in the incidence of trypanosomes in birds coming from localities with different biotopes. No essential difference was found in their incidence in migratory and non migratory birds. In birds several years old the incidence of trypanosomes was higher than in younger birds. Repeated investigations of ringed birds recaptured point out long-lasting infections with avian trypanosomes. A considerable correlation between the incidence of trypanosomes and that of Leucocytozoon, Haemoproteus and microfilariae indicates that avian trypanosomes are probably transmitted by blackflies (Simuliidae), biting midges (Ceratopogonidae) and louse flies (Hippoboscidae).

Animals↗
PubMedDate not supplied

[Control of vectors of human onchocerciasis in intertropical Africa (author's transl)].

First the authors make short comments on the two Simuliidae species complexes vectors of African human onchocerciasis (S. damnosum s.l. and S. neavei), as well as on the reasons for renewed interest in the control of those vectors; then they review the various possible methods of control (ecological, biological, genetical and chemical methods) and they finally detail the methodology of anti-S. damnosum chemical larviciding which is the only kind or large scale control presently used against onchocerciasis vectors. The experiences and results of the previous campaigns resulted in the large Onchocerciasis Control Programme in Volta River Basin (O.C.P.) which now appears as a model for present and future control measures against S. damnosum. This Programme is briefly described, together with its results, problems (reinvasion) and orientations. As a conclusion, the excellent level of control of the vectors and onchocerciasis transmission which is obtained is emphasized and it is expected that in the future new large scale campaigns using O.C.P. experience may be initiated.

Africa↗
PubMed1987

Some unsolved problems in the epidemiology of onchocerciasis.

The descriptive epidemiology of onchocerciasis is well understood in the major foci of infection; a great stimulus to epidemiological research has been the implementation of the first control programme, which led to the eradication of infection in Kenya and, more recently, the vast Onchocerciasis Control Programme in the Volta River Basin of West Africa. However, there are still significant gaps in epidemiological knowledge which hamper the planning of future control programmes and the evaluation of current programmes. The four most important unsolved problems are: the refinement of field diagnostic techniques to identify skin microfilariae at the ultra-low densities that will become common in the late stages of vector-control campaigns; the definitive identification of Onchocerca volvulus infective larvae in Simulium species; strain analysis in the field of microfilariae from humans and of developing stages from Simulium, to determine their potential for ocular pathogenicity; determination of the lifespan, or maximum fecundity span, of adult female O. volvulus after the interruption of transmission. Three other unsolved problems are of enormous interest epidemiologically, although less urgent in practical importance. They are the identification of factors causing severe disease as opposed to heavy infection; the effects of seasonal as opposed to perennial transmission; and the importance of transplacental transmission of microfilariae or soluble antigens.

Africa↗
PubMed1994

Antibacterial peptides in insect vectors of tropical parasitic disease.

The induction and characterization of immune peptides in two groups of medically important insects, the mosquitoes and blackflies, is currently an important research area. Mosquitoes transmit a variety of viral and parasitic diseases including yellow fever, dengue, malaria and lymphatic filariasis. Simuliid black flies are vectors of river blindness. The diseases are together responsible for death and morbidity in millions of people each year. The relationship between inducible peptides and bacterial and parasitic infections in these insects is proving to be a complex one. The identification of an insect defensin (4 kDa) in Aedes aegypti, the yellow fever mosquito, has proved to be the first peptide characterized in a vector of human disease. This inducible molecule appears in the haemolymph in response to bacterial and to a lesser extent filarial infection. The characterization of inducible blackfly peptides has revealed potent inducible anti-Gram-positive as well as anti-Gram-negative activity. In addition, non-self recognition molecules such as phenoloxidase may play a part in differentiating one species of eukaryotic pathogen from another of the same genus. The interactions between the peptides and these other proteins are likely to be important in the establishment of a successful immune response against a parasitic pathogen, particularly as we now know these peptides to have anti-eukaryotic activity (against a range of parasite species). As well as being of fundamental interest in our understanding of host-parasite relationships, the indication that antibacterial peptides are toxic to parasitic organisms has implications for their possible use in the disease vector control strategies of the future. It may also mean that a revision in our understanding of their mode of action, loose as it is, has to take place.

Aedes↗
PubMed1994

Peritrophic matrix of the black fly Simulium vittatum: formation, structure, and analysis of its protein components.

The peritrophic matrix (PM) (same as peritrophic membrane) is secreted by the midgut epithelium of insects and completely surrounds the ingested food. The PM is likely to influence disease transmission by hematophagous insects. As a prelude to a more detailed examination of PM function, we report on morphological and molecular studies of the PM type 1 (PM1) from Simulium vittatum. The blood meal induces major changes in epithelial cell morphology: cells become flattened, microvilli decrease dramatically in number, and organelles redistribute in the cytoplasma. The PM1 forms within minutes of the blood meal. After 6 h the PM1 has reached its maximum thickness (approximately 13 microns) and strength. Two-dimensional gel electrophoresis reveals two major PM1-specific proteins of 66 and 61 kDa. Synthesis of these PM1 proteins is likely to be induced by the blood meal, since they are not detectable prior to blood feeding. The time course of accumulation and disappearance of the PM1 proteins closely correlates with the appearance and disappearance of the PM1 itself.

Animals↗
PubMed1994

Onchocerca lienalis: rapid clearance of microfilariae within the black fly, Simulium vittatum.

A rapid decrease of about a third of the number of Onchocerca lienalis microfilariae (mf) parenterally inoculated into Simulium vittatum black flies occurred within 5 hr postinoculation (pi). The change of mf counts over time was modeled by a segmented linear regression. During 2 hr pi the slope was -3.5 mf/hr (P < or = 0.001) and between 2 and 24 hr pi the slope was -0.1 mf/hr. Although significantly different from the former slope (P < 0.001), the latter was not significantly different from zero (P > 0.2). The decrease could not be attributed to excretion of mf. Microfilariae (especially those heat-killed prior to inoculation) in intermediate stages of destruction were observed in flies dissected 5 hr pi but not immediately after injection. No short- or long-term (24 hr pi) effects of the injection procedure alone on mf survival were evident. A constant proportion of mf was eliminated regardless of dose within a range of 5 to 100 mf/fly during 24 hr pi. However, a second injection of 50 mf/fly 2.5 hr following an injection of the same dose resulted in a significantly lower proportion of mf eliminated. These results suggest that the availability of an active factor(s) in the fly was reduced 2.5 hr after the first inoculation. The change in the availability of this factor(s) may partly explain the change in clearance rate occurring 2 hr pi. Soluble factor(s), rather than a sequence of cellular responses, seems to be involved in the rapid clearance because it occurred in freshly killed flies at a similar rate to that observed in live flies. The hypothesis that mf differ in their innate susceptibility to rapid clearance was rejected as mf that were recovered 2 hr pi and reinoculated into other flies were eliminated faster than unexposed controls. It is concluded that the rapid clearance of mf represents an as yet undescribed immune response to macroparasites of the fly host.

Animals↗
PubMed1995

Simulium damnosum s.l.: identification of inducible serine proteases following an Onchocerca infection by differential display reverse transcription PCR.

Vector-derived proteases are thought to be key to the regulation of filarial infections in Simulium damnosum s.I. To identify proteases of S. damnosum s.I. induced by infection with Onchocerca ochengi, a PCR-based differential display technique was used. By combining this method with homology-based serine protease primers transcripts can be detected from S. damnosum s.I. RNA.

Amino Acid Sequence↗
PubMed1995

Onchocerca spp: a "family" of secreted acidic proteins expressed by infective larvae in blackflies.

Biosynthetic labeling of developing larvae of Onchocerca in blackflies has been used to characterize a group of stage-specific, secreted proteins produced by vector-stage parasites. These are highly acidic molecules (pI 4.4-5.1) present in at least three members of the genus (O. volvulus, O. lienalis, O. ochengi) that exhibit minor heterogeneity among species in apparent molecular mass (between 18 and 23 kDa). In O. volvulus, there are two polypeptides that run as a doublet of 18 and 20 kDa. In O. lienalis and O. ochengi, single polypeptides of 23 and 20 kDa were detected. The processes of synthesis and secretion appear to be temperature-sensitive and dissociated events. Experiments with O. volvulus in Simulium damnosum sl revealed that synthesis is initiated in second stage larvae and increases in infective-stage parasites: Secretion occurs when larvae leave the vector and enter the phase of development associated with the vertebrate host. Third-stage larvae of O. lienalis were shown to continue to express and accumulate the 23-kDa protein with age. The primary organ of secretion, as indicated by dissection, was the glandular esophagus. These data point to an important biological role for this group of molecules and suggest that they may belong to a family of related products. Because they have the distinctive characteristics of being secreted larval acidic proteins, we propose the acronym SLAP pending further insights into their functional properties.

Animals↗
PubMed1995

The black fly Simulium vittatum trypsin gene: characterization of the 5'-upstream region and induction by the blood meal.

The events leading to blood digestion in hematophagous insects are not well understood at the molecular level. Here we report on the characterization of a trypsin gene from the black fly Simulium vittatum. Southern blot analysis indicated that the S. vittatum genome contains at least two trypsin genes. Primer extension experiments identified two closely spaced transcription initiation sites, 3 bp apart. A genomic clone containing the trypsin gene was restriction mapped and the nucleotide sequence of the 5'-upstream region was determined. Several sequence elements were identified, including a consensus TATA box 35 nucleotides upstream from the transcription initiation site, a consensus arthropod initiator site at position -7, and two conserved sequence elements, 5'GGATTAA (position -77) and 5'TGTTTCCT (position -148). The latter two elements are present at comparable distances from the transcription initiation sites in black fly and mosquito trypsin genes. Significant amounts of trypsin mRNA were detected in guts of sugar-fed flies. Upon blood feeding, trypsin mRNA levels gradually increased to reach twice the initial abundance at 8 hr after blood ingestion. In contrast to other hematophagous insects, the induced mRNA level persists for a prolonged period of time (at least 48 hr) after blood ingestion. The results of this study provide information that may be useful for the expression of transgenes in insects of medical importance.

Animals↗
PubMed1997

Simulium damnosum s.l.: isolation and identification of prophenoloxidase following an infection with Onchocerca spp. using targeted differential display.

Phenoloxidase (PO) is the key enzyme for melanin synthesis and plays an important role in the defense and recognition of pathogens in insects and other arthropods. We now report the upregulated transcription of the gene encoding the precursor of PO, prophenoloxidase, in Onchocerca-infected Simulium damnosum s.l., the main vector of human and bovine onchocerciasis in subsaharan Africa. Using homology-based generic primers in a polymerase chain reaction-based targeted differential display, the gene itself was identified and partially sequenced.

Amino Acid Sequence↗