Temporal and spatial variations in phenology patterns of blackflies (Diptera: Simuliidae) and their longitudinal distribution along oligotrophic freshwater system

摘要: Black flies are very important component of freshwater lotic habitats and they have high veterinary and medical significance, because the majority of females need a blood meal to produce eggs. This study was done at Plitvice lakes National Park (Croatia) in a wide range of lotic freshwater habitats (spring, streams and tufa barriers-barrage lake outlets). Adults were sampled monthly from March 2007 until March 2008 using pyramid-type emergence traps at 9 locations. A total of 38012 specimens comprising 10 species were collected. The dominated genus was Simulium, while the most abundant species was Simulium angustipes. A strong relationship was confirmed by MDS analysis between species composition and their habitat type. Simulium angustipes was highly related to lake outlets. The blackfly communities at all sites were dominated by species typical for the rhithral zone, but there was a shift in species composition along a longitudinal gradient, from the hypocrenal-epirhithral to the epirhitral-metarhithral zone. All species were univoltine, except Simulium costatum, Simulium angustipes, Simulium monticola, Simulium trifasciatum and Simulium variegatum. Simulium costatum that was present on 8 from 9 studied sites had a multivoltine cycle on sites with constant water temperatures and bi or univoltine cycle on sites with variable water temperature. Simulium angustipes had multiple generations per year, while Simulium monticola, Simulium trifasciatum and Simulium variegatum had two generations per year.