Blar i forfatter "Hemmingsen, Willy"
-
Caligus elongatus and other sea lice of the genus Caligus as parasites of farmed salmonids: A review
Hemmingsen, Willy; MacKenzie, Ken; Sagerup, Kjetil; Remen, Mette; Bloch-Hansen, Karin; Imsland, Albert (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-24)This review was prompted by reports of unusually large numbers of sea lice tentatively identified as <i>Caligus elongatus</i> infesting farmed salmon in northern Norway. Following a brief introduction to the sea lice problem in salmonid aquaculture, the review is divided into a further eight sections. The first is a review of existing information on the life cycle and behaviour of <i>Caligus</i> ... -
Comparative analysis of the cytoarchitecture of the excretory bladder of adult Digenea (Platyhelminthes) with consideration of the presence of mineralized excretory corpuscles in marine and freshwater adult worms
Poddubnaya, Larisa G.; Hemmingsen, Willy; MacKenzie, Ken (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-01)The ultrastructural differences are shown between the cytoarchitecture of the excretory bladder and excretory inclusions in four digenean species, two azygiids, the marine Otodistomum cestoides and the freshwater Azygia lucii, the marine derogenid Derogenes varicus and the freshwater allocreadiid Acrolichanus auriculatus. The unusual cytoarchitecture of the bladder epithelium of the azygiid digeneans, ... -
Failure of two consecutive annual treatments with ivermectin to eradicate the reindeer parasites (Hypoderma tarandi, Cephenemyia trompe and Linguatula arctica) from an island in northern Norway.
Nilssen, Arne C.; Hemmingsen, Willy; Haugerud, Rolf E. (Journal article; Tidsskriftartikkel; Peer reviewed, 2002)The highly efficient endectocide ivermectin is used to reduce the burden of parasites in many semidomestic reindeer herds in northern Fennoscandia. In the autumn of 1995 and 1996 all reindeer on the island of Silda (42 km2) were treated with ivermectin in an attempt to eradicate the warble fly (Hypoderma (=Oedemagena) tarandi (L.)), the nose bot fly (Cephenemyia trompe (Modeer)) (Diptera: Oestridae) ... -
Gyrodactylus triglopsi n. sp. (Monogenea: Gyrodactylidae) from the Gills of Triglops nybelini Jensen, 1944 (Teleostei: Cottidae) in the Barents Sea
Hansen, Haakon; Alvestad, Anja Helene; MacKenzie, Ken; Darrud, Mari; Karlsbakk, Egil; Hemmingsen, Willy; Arneberg, Per (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-04-28)<i>Introduction</i> - Monogeneans of the genus <i>Gyrodactylus</i> were found on the gills of specimens of the bigeye sculpin <i>Triglops nybelini</i> Jensen, 1944 caught by trawl in the Barents Sea in January–February 2016.<p> <p><i>Methods</i> - Morphological preparations of the parasites were examined and photographed under a microscope at magnifcations of×100–1000 and morphometric analyses ... -
Morphological features of the testis of freshwater blood flukes of the genus Sanguinicola Plehn, 1905, with consideration of the testicular patterns in the Aporocotylidae
Poddubnaya, Larisa G.; Zhokhov, Alexander E.; Hemmingsen, Willy; MacKenzie, Ken (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-13)This is the first detailed study assessing the morphological features of the testis and testicular sperm of members of the freshwater blood flukes Sanguinicola sp. from Leuciscus idus (Cyprinidae) and for S. volgensis from Pelecus cultratus (Cyprinidae), and the marine blood fluke Aporocotyle simplex from Hippoglossoides platessoides (Pleuronectidae). The present study reports a unique feature in ... -
Parasite faunas of farmed cod and adjacent wild cod populations in Norway: a comparison
Heuch, Peter Andreas; Jansen, Peder Andreas; Hansen, Haakon; Sterud, Erik; MacKenzie, Ken; Haugen, Pål; Hemmingsen, Willy (Journal article; Tidsskriftartikkel; Peer reviewed, 2011-07-14)Atlantic cod Gadus morhua L. is host to more than 120 parasite species. Background abundance of these parasite species on adjacent wild hosts determines the infection pressure on cod farmed in open pens. In 2006, 2007 and 2008, 343 cod were collected from 4 locations along the coast of Norway: Øksfjord, Kvarøy, Brønnøysund and Ålesund. Freshly killed wild local cod, wild migratory cod, hatchery-reared ... -
Treatment of reindeer with ivermectin. Effect on dung insect fauna.
Nilssen, Arne C.; Åsbakk, Kjetil; Oksanen, Antti; Haugerud, Rolf E.; Hemmingsen, Willy (Journal article; Tidsskriftartikkel; Peer reviewed, 1999) -
Ultrastructural evidence for the participation of muscle cells in the formation of extracellular matrices in aporocotylid blood flukes (Digenea)
Poddubnaya, Larisa G.; Zhokhov, Alexander E.; Hemmingsen, Willy; Gibson, David I. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-05)The muscle cells and extracellular matrices (ECMs) of two teleost-infecting blood flukes belonging to distinct evolutionary lineages of the Aporocotylidae (Digenea) were examined using Transmission Electron Microscopy. Four morphotypes of muscle cells were found in the freshwater species Sanguinicola sp., but were considered to be various developmental stages of a single cisternic type. In the marine ...