6 research outputs found

    Catches of bloodsucking blackflies (Diptera: Simuliidae) tell different stories depending on sampling method

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    To compare different sampling techniques, blackflies were captured along six Swedish rivers in 2001 and 2002, using two fundamentally different methods: (1) daytime trapping with a vehicle-mounted net, and (2) exposure of CO2-baited traps. The methods were selectively different for different species of blackflies. Some species were caught relatively more frequently by vehicle trapping and others by CO2 trapping. Only rarely were species catches proportionally similar between the two methods.We suggest that the different catch success reflects differences in host-searching behaviour in the species present and that the sampling methods are complementary

    Catches of bloodsucking blackflies (Diptera: Simuliidae) tell different stories depending on sampling method

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    To compare different sampling techniques, blackflies were captured along six Swedish rivers in 2001 and 2002, using two fundamentally different methods: (1) daytime trapping with a vehicle-mounted net, and (2) exposure of CO 2 -baited traps. The methods were selectively different for different species of blackflies. Some species were caught relatively more frequently by vehicle trapping and others by CO 2 trapping. Only rarely were species catches proportionally similar between the two methods. We suggest that the different catch success reflects differences in host-searching behaviour in the species present and that the sampling methods are complementary

    Indirect effects of river regulation : consequences for landbirds of reduced numbers of aquatic insects

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    Abstrakt: Jag har undersökt hur älvreglering påverkar mängden knott (Tvåvingar: Simuliidae) längs flera norrlandsälvar och vilka konsekvenser denna påverkan får för den landlevande fågelfaunan. Studien visar att utbyggnad av älvar har en negativ effekt på mängden knott. Det fanns sju gånger högre tätheter av knott längs "orörda älvar" jämfört med utbyggda älvar. Skillnaden i antal knott mellan älvtyperna var mycket större för knotthanar än för knotthonor, vilket förklaras av att honorna är rörligare eftersom de flyger och letar efter blod. Knott lever av blod från ett flertal däggdjur och fåglar och visar en stor variation i värd-specificitet mellan olika arter. Jag fann en högre frekvens av haemosporida blod parasiter (Leucocytozoon) i fåglar längs "orörda" Vindelälven jämfört med den reglerade Umeälven. Detta mönster stämmer väl överens med tätheten fågelparasiterande knott som är lägre längs Umeälven. Knott attackerade främst värdar som var stora och vanliga. Fågelsamhällets sammansättning skiljde sig mellan orörda och utbyggda älvdalar. Tätheten av icke insektsätande fåglar tenderade att minska, efter häcksäsongen, längs orörda älvar medan den ökade längs utbyggda älvar. Den insektsätande fågeln svartvit flugsnappare (Ficedula hypoleuca Pallas) uppvisade större häckningsframgång längs orörda älvar jämfört med utbyggda älvar. Detta är förmodligen en effekt av den större mängden insekter som finns längs orörda älvar.The effects of river regulation on blackfly (Diptera: Simuliidae) abundances and consequences for the avifauna in terrestrial environments were studied along multiple rivers in northern Sweden. I found that impoundment of rivers has detrimental effect to blackfly abundances. The densities of large-river breeding blackfly species were several-fold higher along free-flowing than along regulated rivers. The difference in abundances was much larger in males than blood-seeking females. Blackflies attacked a variety of mammalian and avian hosts and showed different levels of host-specificity between species. I found higher prevalence of haemosporidian blood parasites (Leucocytozoon) in birds along the free-flowing Vindel River in comparison to the regulated Ume River, where the lower densities of ornithophilic blackflies were reduced. Blood-seeking blackflies predominantly attacked large and/abundant hosts. Assemblages of birds differed between valleys of regulated and free-flowing rivers. Densities of noninsectivorous birds tended to decrease along free-flowing rivers in the post-breeding season, but increased along regulated rivers at the same time. Insectivorous European pied flycatcher (Ficedula hypoleuca Pallas) showed greater fledging success along free-flowing than regulated rivers, which probably reflects the higher insect abundances found along freeflowing rivers

    Vertebrate host specificity of wild-caught blackflies revealed by mitochondrial DNA in blood.

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    Blood-feeding blackflies (Diptera: Simuliidae) transmit pathogens, harass vertebrate hosts and may cause lethal injuries in attacked victims, but with traditional methods it has proved difficult to identify their hosts. By matching mitochondrial DNA (mtDNA) sequences in blood collected from engorged blackflies with stored sequences in the GenBank database, relationships between 17 blackfly species and 25 species of vertebrate hosts were revealed. Our results demonstrate a predominance of large hosts and marked discrimination between blackflies using either avian or mammalian hosts. Such information is of vital interest in studies of disease transmission, coevolutionary relationships, population ecology and wildlife management
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