| 1. |
- Sigvald, Roland, et al.
(author)
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Molecular identification of bloodmeals and species composition in Culicoides biting midges
- 2013
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In: Medical and Veterinary Entomology. - : Wiley. - 0269-283X .- 1365-2915. ; 27, s. 104-112
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Journal article (peer-reviewed)abstract
- Investigations of host preferences in haematophagous insects, including Culicoides biting midges (Diptera: Ceratopogonidae), are critical in order to assess transmission routes of vector-borne diseases. In this study, we collected and morphologically identified 164 blood-engorged Culicoides females caught in both light traps and permanent 12-m high suction traps during 20082010 in Sweden. Molecular analysis of the mitochondrial cytochrome c oxidase subunit I (COI) gene in the biting midges was performed to verify species classification, discern phylogenetic relationships and uncover possible cryptic species. Bloodmeal analysis using universal vertebrate cytochrome b primers revealed a clear distinction in host selection between mammalophilic and ornithophilic Culicoides species. Host sequences found matches in horse (n = 59), sheep (n = 39), cattle (n = 26), Eurasian elk (n = 1) and 10 different bird species (n = 18). We identified 15 Culicoides species previously recorded in Scandinavia and four additional species haplotypes that were distinctly different from the described species. All ornithophilic individuals (n = 23) were caught exclusively in the suction traps, as were, interestingly, almost all mammalophilic species (n = 41), indicating that many biting midge species may be able to cover long distances after completing a bloodmeal. These results add new information on the composition of Culicoides species and their host preferences and their potential long-distance dispersal while blood-engorged.
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| 2. |
- Brännström, Sara
(author)
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Molecular investigations of cytochrome c oxidase subunit I (COI) and the internal transcribed spacer (ITS) in the poultry red mite, Dermanyssus gallinae, in northern Europe and implications for its transmission between laying poultry farms
- 2011
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In: Medical and Veterinary Entomology. - : Wiley. - 0269-283X .- 1365-2915. ; 25, s. 402-412
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Journal article (peer-reviewed)abstract
- Samples of Dermanyssus gallinae (DeGeer) (Acari: Dermanyssidae) from more than 49 Norwegian and Swedish laying poultry farms, and additional samples collected from Scottish, Finnish, Danish and Dutch layer farms, were compared genetically. Analysis of partial mitochondrial gene cytochrome c oxidase subunit I (COI) sequences of mites from Norway and Sweden revealed 32 haplotypes. Only single haplotypes were found on most farms, which suggests that infections are recycled within farms and that transmission routes are few. Both Norwegian and Swedish isolates were found in the two major haplogroups, but no haplotypes were shared between Norway and Sweden, indicating little or no recent exchange of mites between these countries. There appears to be no link between haplotypes and geographical location as identical haplotypes were found in both the northern and southern Swedish locations, and haplotypes were scattered in locations between these extremes. The current data suggest that wild birds in Sweden are not a reservoir for D. gallinae infection of layer farms as their mites were genetically distinct from D. gallinae of farm layer birds. Transmission of the poultry red mite in Scandinavia is thus likely to depend on synantropic factors such as the exchange of contaminated material or infested birds between farms or facilities.
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| 3. |
- Hesson, Jenny C., 1980-, et al.
(author)
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A sensitive and reliable restriction enzyme assay to distinguish between the mosquitoes Culex torrentium and Culex pipiens
- 2010
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In: Medical and Veterinary Entomology. - : Wiley. - 0269-283X .- 1365-2915. ; 24:2, s. 142-149
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Journal article (peer-reviewed)abstract
- Culex pipiens pipiens Linnaeus and Culex torrentium Martini (Diptera: Culicidae) are closely related vector species that exist sympatrically in Europe. The two species are morphologically almost identical and can only be distinguished with certainty by characters of the male genitalia. Hence, correct species identification and conclusions on distribution and vector status are very difficult and often neglected. Therefore, we developed a reliable and simple mitochondrial cytochrome c oxidase subunit I (COI) gene restriction enzyme assay to discriminate between Cx. pipiens and Cx. torrentium, based on the analysis of morphologically identified male specimens. We sequenced approximately 830 bp in the 3′ region of the mitochondrial COI gene of 18 morphologically identified males of Cx. pipiens and Cx. torrentium. Two restriction enzymes (FspBI and SspI) that could distinguish between the two species according to species-specific differences in these sequences were chosen. The restriction enzymes were tested on 227 samples from Sweden and verified by sequencing 44 of them. The enzyme FspBI correctly identified all investigated samples; the enzyme SspI identified all samples except one Cx. torrentium. We hope the method and the findings presented here will help to shed light on the true distribution and relative proportions of the two species in Europe.
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| 4. |
- Jaenson, T. G. T., et al.
(author)
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Evaluation of extracts and oils of tick-repellent plants from Sweden
- 2005
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In: Medical and Veterinary Entomology. - : Wiley. - 0269-283X .- 1365-2915. ; 19:4, s. 345-352
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Journal article (peer-reviewed)abstract
- Leaves of Myrica gale Linnaeus (Myricaceae), Rhododendron tomentosum (Stokes) H. Harmaja (formerly Ledum palustre Linnaeus: Ericaceae) and Artemisia absinthium Linnaeus (Asteraceae) were extracted with organic solvents of different polarities and the essential oils of leaves were obtained by steam distillation. The extracts or oils were tested in the laboratory for repellency against host-seeking nymphs of Ixodes ricinus Linnaeus (Acari: Ixodidae). Rhododendron tomentosum oil, 10%, diluted in acetone, exhibited 95% repellency; R. tomentosum and A. absinthium extracts in ethyl acetate, > 70% repellency; A. absinthium extract in hexane, similar to 62% repellency; and M. gale oil, 10%, similar to 50% repellency on I. ricinus nymphs. Compounds in the leaf extracts or in the oils were collected by solid phase microextraction (SPME) and identified by gas chromatography-mass spectrometry (GC-MS) and/or MS. Characteristic volatiles detected from oil or extract of M. gale were the monoterpenes 1,8-cineole, alpha-terpineol, 4-terpineol and thujenol; and of R. tomentosum myrcene and palustrol. Characteristic volatiles from leaf extracts of A. absinthium were sabinene, oxygenated monoterpenes, e.g. thujenol and linalool, and geranyl acetate. Each plant species synthesized numerous volatiles known to exhibit acaricidal, insecticidal, 'pesticidal' and/or arthropod repellent properties. These plants may be useful sources of chemicals for the control of arthropods of medical, veterinary or agricultural importance.
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| 5. |
- Jaenson, Thomas G.T. 1948-, et al.
(author)
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Risk indicators for the tick Ixodes ricinus and Borrelia burgdorferi sensu lato in Sweden
- 2009
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In: Medical and Veterinary Entomology. - : Blackwell. - 0269-283X .- 1365-2915. ; 23:3, s. 226-237
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Journal article (peer-reviewed)abstract
- The distributional area of the tick Ixodes ricinus (L.), the primary European vector to humans of Lyme borreliosis spirochaetes (Borrelia burgdorferi sensu lato) and tick-borne encephalitis virus, appears to be increasing in Sweden. It is therefore important to determine which environmental factors are most useful to assess risk of human exposure to this tick and its associated pathogens. The geographical distribution of I. ricinus in Sweden was analyzed with respect to vegetation zones and climate. The northern limit of I. ricinus and B. burgdorferi s.l. in Sweden corresponds roughly to the northern limit of the southern boreal vegetation zone, and is characterized climatically by a mean duration of 150 days with snow cover and a vegetation period averaging 170 days. The zoogeographical distribution of I. ricinus in Sweden can be classified as southerly-central, with the center of the distribution south Limes Norrlandicus. Ixodes ricinus nymphs from 13 localities in different parts of Sweden were examined for presence of B. burgdorferi s.l. and found to be infected with B. afzelii and B. garinii. Tick sampling localities were characterized on the basis of density of Borrelia-infected I. ricinus nymphs, presence of specific mammals, dominant vegetation and climate. Densities of I. ricinus nymphs and Borrelia-infected nymphs were significantly correlated, and nymphal density can thus serve as a general indicator of risk for exposure to Lyme borreliosis spirochaetes. Analysis of data from this and other studies suggest that high densities of Borrelia-infected nymphs typically occur in coastal, broad-leaf vegetation and in mixed deciduous/spruce vegetation in southern Sweden. Ixodes ricinus populations consistently infected with B. burgdorferi s.l. can occur in biotopes with (i) shrews, rodents, hares and birds, (ii) shrews, rodents, hares, deer and birds, (iii) and on islands where the varying hare (Lepus timidus) is the only mammalian tick host.
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| 6. |
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| 7. |
- Schafer, M.L., et al.
(author)
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Biological diversity versus risk for mosquito nuisance and disease transmission in constructed wetlands in southern Sweden
- 2004
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In: Medical and Veterinary Entomology. - 0269-283X .- 1365-2915. ; 18:3, s. 256-267
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Journal article (peer-reviewed)abstract
- In southern Sweden, many wetlands have been constructed, and maintaining or increasing biological diversity is often included in the aims. Some wetlands are constructed near human settlements, thus raising the problem of wetlands being associated with mosquitoes (Diptera: Culicidae). Increased biodiversity (including mosquito diversity) is considered desirable, whereas mosquito nuisance from a human point of view is not. Adult mosquito abundance, diversity and species assemblages of constructed wetlands were compared to natural wetlands. The potential of constructed wetlands for mosquito nuisance and transmission of mosquito-borne viruses was evaluated. The study areas included five constructed and four natural wetlands. Mosquito abundance and species richness were higher in the natural than in the constructed wetlands, and showed a positive correlation with wetland size. Mosquito species assemblages formed three clusters, which were not explained by origin, size and water permanence of wetlands. In a redundancy analysis, however, mosquito faunas showed significant relationships with these variables, and size and origin of wetlands were most important. Major nuisance species (multivoltine species feeding on mammals and laying eggs on soil) were found in all wetlands, although in relatively low numbers. Risk assessment for Sindbis virus transmission showed moderate risk for two constructed wetlands near human settlements. It is concluded that small size of constructed wetlands has the advantage of low mosquito numbers from a human point of view. The use of functional groups is recommended as a tool for presenting mosquito data to the public, and for helping communication between scientists and administrative decision makers.
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| 8. |
- Selden, A. I., et al.
(author)
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Chironomid midge sensitization in sewage workers : case study
- 2013
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In: Medical and Veterinary Entomology. - Hoboken, USA : Wiley-Blackwell. - 0269-283X .- 1365-2915. ; 27:3, s. 346-348
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Journal article (peer-reviewed)abstract
- Non-biting chironomid midges (Diptera: Chironomidae) may cause sensitization and allergic reactions in humans and have recently been identified as a potential health problem in Swedish municipal sewage treatment plants. To investigate, on a pilot scale, the allergenic potential of chironomids in sewage workers, all workers (n = 8) at a sewage treatment plant and local controls (n = 16) completed a symptom questionnaire, underwent measurement of the fraction of nitric oxide in exhaled air, spirometry, and provided serum samples for the determination of atopy status and the prevalence of specific immunoglobulin E (IgE) antibodies against Chironomus thummi (Chi t) using a commercial fluorescence enzyme immunoassay (FEIA). Three sewage workers (38%) but no controls (0%) were FEIA positive for C. thummi-specific IgE antibodies (P < 0.05). No other health-related findings were significantly different between the groups. The study suggested that occupational exposure to Chironomids may cause sensitization with circulating IgE-antibodies in sewage workers.
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| 9. |
- Swanson, DA, et al.
(author)
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Spatial stratification of host-seeking Diptera in boreal forests of northern Europe
- 2012
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In: Medical and Veterinary Entomology. - Malden, USA : Wiley-Blackwell. - 0269-283X .- 1365-2915. ; 26:1, s. 56-62
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Journal article (peer-reviewed)abstract
- The stratification of haematophagous Diptera was assessed in two boreal forests in northern Sweden by placing traps baited with carbon dioxide at 1.5 m, 5.0 m and 10.0 m above the ground. More than 40 000 specimens were captured, including 617 biting midges (Ceratopogonidae), 4029 mosquitoes (Culicidae) and 36 092 black flies (Simuliidae). Catches at the various trap heights reflected the general vertical distribution of the preferred hosts, with mammalophilic flies predominating (68.6%) in catches at 1.5 m and ornithophilic flies (42.4%) in catches at 10.0 m; however, most flies that use host birds at ground level were caught in the lowest traps (e.g. 85.1% of Simulium annulus were collected at 1.5 m). Within-species variation in vertical patterns between forests suggests plasticity in responses to environmental factors such as vegetative structure.
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| 10. |
- Torr, S. J., et al.
(author)
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Responses of tsetse flies, Glossina morsitans morsitans and Glossina pallidipes, to baits of various size
- 2011
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In: Medical and Veterinary Entomology. - : Wiley. - 0269-283X .- 1365-2915. ; 25:4, s. 365-369
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Journal article (peer-reviewed)abstract
- Recent studies of Palpalis group tsetse [Glossina fuscipes fuscipes (Diptera: Glossinidae) in Kenya] suggest that small (0.25 x 0.25 m) insecticide-treated targets will be more cost-effective than the larger (>= 1.0 x 1.0 m) designs currently used to control tsetse. Studies were undertaken in Zimbabwe to assess whether small targets are also more cost-effective for the Morsitans group tsetse, Glossina morsitans morsitans and Glossina pallidipes. Numbers of tsetse contacting targets of 0.25 x 0.25 m or 1.0 x 1.0 m, respectively, were estimated using arrangements of electrocuting grids which killed or stunned tsetse as they contacted the target. Catches of G. pallidipes and G. m. morsitans at small (0.25 x 0.25 m) targets were, respectively, similar to 1% and similar to 6% of catches at large (1.0 x 1.0 m) targets. Hence, the tsetse killed per unit area of target was greater for the larger than the smaller target, suggesting that small targets are not cost-effective for use against Morsitans group species. The results suggest that there is a fundamental difference in the host-orientated behaviour of Morsitans and Palpalis group tsetse and that the former are more responsive to host odours, whereas the latter seem highly responsive to visual stimuli.
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