Geir Kjølberg Knudsen
Overingeniør
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Høsten/vinteren 2022-2023 ble det utført et forsøk på NIBIO Landvik med ulike metoder for utvasking av frø fra bær av svartsurbær (Aronia melanocarpa), samt hvordan disse behandlingene påvirker frøets spireevne. Metodene var lett vasking (fjerning av plantesaft og mindre plantedeler) og grundig vasking (fjerning av plantesaft og det meste av fruktkjøttet), enten for hånd eller ved hjelp av en industrielt tilpassa vaskemaskin. Tidsstudier, utregnet som arbeidstid (minutter) pr kg med friske bær, viste at den totale tida til utvasking og rensing av frø av svartsurbær ble omtrent halvert når det ble vasket med maskin sammenlignet med vasking for hånd, uansett hvor nøye/grundig vaskingen ble utført. Mest effektivt var det å maskinvaske ut frøet i en grundig prosess hvor plantesaft og mesteparten av fruktkjøttet ble fjernet før frørensing (6,5 minutter pr kg bær). Under vaskeprosessen, både ved bruk av vaskemaskin og for hånd, ble det vasket ut mer frø (flotert bort sammen med fruktkjøttet) når det ble vasket grundig enn ved mer lettvint vasking. Ved maskinvasking utgjorde denne forskjellen 1 g frø pr kg bær (8%). Frøet som var igjen etter den grundige vaskingen var imidlertid tyngre og spirte bedre enn frøet som var lettere vasket. I middel for to ulike stratifiseringstider (90 og 120 dager), var spireevnen hos frø som var lett og grundig maskinvaska henholdsvis 65 og 77%. Selv om spirehastigheten (opptelling etter 7 dager) var raskere hos frø som var stratifisert i 120 dager, var det ikke nødvendig med mer enn 90 dagers stratifisering for å oppnå maksimal spireevne. I middel for 4 ulike vaskemetoder var spireevnen etter opptelling etter 35 dager 66-67 % uansett om stratifiseringslengden var 90 eller 120 dager. Ut fra en helhetsvurdering anses en forholdsvis grundig maskinvasking, med fjerning av plantesaft og mye av fruktkjøttet, som den mest effektive metoden ved utvasking av frø av svartsurbær. Noe frø vil gå tapt i en slik grundige renseprosess, men det tapte frøet er lett og har dårlig spireevne.
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Lars T. Havstad John Ingar Øverland Geir Kjølberg Knudsen Hogne Prestegård Victoria Stornes MoenSammendrag
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Trygve S. Aamlid Geir Kjølberg Knudsen Ove Hetland Victoria Stornes Moen Kristine SundsdalSammendrag
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Trygve S. Aamlid Geir Kjølberg Knudsen Hogne Prestegård Trond Olav Pettersen Kristine Sundsdal Victoria Stornes MoenSammendrag
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Trygve S. Aamlid Geir Kjølberg Knudsen Hogne Prestegård Trond Olav Pettersen Kristine Sundsdal Ole Sigvart Dahlen John Ingar ØverlandSammendrag
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Lars T. Havstad John Ingar Øverland Geir Kjølberg Knudsen Hogne Prestegård Åsmund Erøy Victoria Stornes MoenSammendrag
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Trygve S. Aamlid Ellen Johanne Svalheim Hans Martin Hanslin Geir Kjølberg Knudsen Harald Bratli Thomas BreibySammendrag
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Lars T. Havstad John Ingar Øverland Trygve S. Aamlid Trond Gunnarstorp Geir Kjølberg Knudsen Jon SælandSammendrag
Desiccation with diquat about one week before seed harvest has been common practise in Norwegian clover seed production. However, after withdrawal of diquat in 2020, clover seed growers no longer have desiccators available. In 2019 and 2020, six field trials in red clover and two field trials in white clover were carried out to evaluate alternative chemical products at different rates and at two different spraying dates, either early at 50% mature seed heads and / or late at 65% mature seed heads. Products included, either for one or two years, was Spotlight Plus (carfentrazonethyl), Beloukha (pelargonic acid), Glypper (glyphosate), Gozai (Pyraflufen-ethyl), Harmonix LeafActive (acetic acid), Harmonix FoliaPlus (pelargonic acid), Flurostar (fluroxypyr) and Saltex (sodium chloride) and liquid urea-based fertilizers. In addition, swathing was examined as an alternative in two red clover trials in 2020. While none of the tested chemicals were superior to diquat, the most promising alternatives were Harmonix FoliaPlus and Harmonix LeafActive in red clover or Harmonix FoliaPlus in white clover. Although usually less effective than these products, Beloukha also had an acceptable desiccation effect, especially when sprayed early and late. Swathing before harvest, using finger bar cutters, was an effective drying method under favourable weather conditions.
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Trygve S. Aamlid John Ingar Øverland Lars T. Havstad Ellen Johanne Svalheim Trond Olav Pettersen Ove Hetland Geir Kjølberg Knudsen Kristine Sundsdal Victoria Stornes MoenSammendrag
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Lars T. Havstad Trond Gunnarstorp John Ingar Øverland Geir Kjølberg Knudsen Åsmund Erøy Olav Langmyr Victoria Stornes MoenSammendrag
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Trygve S. Aamlid Birgitte Henriksen John Ingar Øverland Jon Sæland Trond Gunnarstorp Erik Aaberg Harald Solberg Geir Kjølberg Knudsen Olav Langmyr Anne Friederike Borchert Victoria Stornes Moen Ove HetlandSammendrag
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Hans Martin Hanslin Ellen Johanne Svalheim Geir Kjølberg Knudsen Trygve S. Aamlid Harald Bratli Jörgen Wissmann Peter EdmanSammendrag
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Hans Martin Hanslin Ellen Johanne Svalheim Geir Kjølberg Knudsen Trygve S. Aamlid Harald Bratli Jörgen WissmannSammendrag
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Hans Martin Hanslin Ellen Johanne Svalheim Geir Kjølberg Knudsen Trygve S. Aamlid Harald Bratli Jörgen WissmannSammendrag
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Trygve S. Aamlid Ellen Johanne Svalheim Geir Kjølberg Knudsen Hans Martin Hanslin H. BratlieSammendrag
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Hans Martin Hanslin Ellen Johanne Svalheim Geir Kjølberg Knudsen Trygve S. Aamlid Harald Bratli Jörgen Wissmann Torben kastrup PedersenSammendrag
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Hans Martin Hanslin Ellen Johanne Svalheim Harald Bratli J. Wissmann Geir Kjølberg Knudsen J. Kollmann Trygve S. AamlidSammendrag
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Trygve S. Aamlid Ellen Johanne Svalheim Geir Kjølberg Knudsen Harald Bratli J. Wissmann Peter EdmanSammendrag
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Hans Martin Hanslin Trygve S. Aamlid Ellen Johanne Svalheim Geir Kjølberg Knudsen Harald Bratli Karin NormannSammendrag
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Lars T. Havstad Trond Gunnarstorp John Ingar Øverland Geir Kjølberg Knudsen Olav Langmyr Kristine SundsdalSammendrag
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Conservation biological control (CBC) is a promising tool for ecological intensification that aims to establish resilient natural enemy populations that contribute to pest management with reduced use of pesticides and at the same time support native biodiversity in agroecosystems. Yet the impact of natural enemies in CBC is often limited due to missing resources such as food, habitat, and hibernation shelters. Here, we studied a CBC strategy that incorporates these essential resources combined with semiochemicals, focusing on how the common green lacewing can enhance biological control of aphids. In a 4-year field study conducted at three locations in the region of East Norway, we developed a CBC strategy combining the three measures ATTRACT (a ternary attractant that increase lacewing egg laying), FOOD (floral buffer strips), and SHELTER (insect hotels for overwintering survival) to increase aphid biological control in spring barley. We recorded the number of lacewings, ladybirds, hoverflies, parasitized aphid mummies, and the two cereal aphid species Sitobion avenae and Rhopalosiphum padi. Our CBC strategy resulted in a significant increase in lacewing activity and significant aphid suppression. At all three locations and over the 4-year period, aphid infestation was below the economic damage threshold in the field plots using CBC measures. In contrast, during two of the years, the density of the aphid infestation in the control plots was significantly above the damage threshold. We found evidence that use of the ternary attractant supported green lacewings but led to loss of ladybirds, hoverflies, and parasitoids, even though flower strips were used as alternative resources. Our study shows a promising increase in lacewing activity in the agricultural landscape and high biological control of aphids in barley. Long-term field studies are needed to evaluate the impact on non-target species and the agroecosystem before practical application of this approach can be considered.
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Trygve S. Aamlid Birgitte Henriksen Jon Ingar øverland Trond Gunnarstorp Jon Sæland Geir Kjølberg Knudsen Ove HetlandSammendrag
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Lars T. Havstad John Ingar Øverland Kristine Sundsdal Geir Kjølberg Knudsen Trond Olav PettersenSammendrag
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Lars T. Havstad Trond Gunnarstorp John Ingar Øverland Geir Kjølberg Knudsen Olav Langmyr Kristine SundsdalSammendrag
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Gunda Thöming Sándor Koczor Ferenc Szentkirályi Hans Ragnar Norli Marco Tasin Geir Kjølberg KnudsenSammendrag
In a field-trapping experiment with plant volatiles, we observed notably high attraction of green lacewing (Chrysotropia ciliata) males to the compound p-anisaldehyde. Based on this finding, we initiated the present study to elucidate this phenomenon and to investigate the chemical ecology of C. ciliata. Scanning electron microscopy revealed elliptical glands abundantly distributed on the 2nd to 6th abdominal sternites of C. ciliata males, whereas females of the species completely lacked such glands. No p-anisaldehyde was found in extractions of body parts of C. ciliata. Methyl p-anisate and p-methoxybenzoic acid were identified exclusively in the extract from abdominal segments 2–8 of males. Field-trapping experiments revealed no attraction of C. ciliata to either methyl p-anisate or p-methoxybenzoic acid. In contrast, males showed marked attraction to p-anisaldehyde in the field and antennae showed strong responses to this compound. Headspace collections in the field from living insects in their natural environment and during their main daily activity period indicated that p-anisaldehyde was emitted exclusively by C. ciliata males. Our overall results suggest that p-anisaldehyde might serve as a male-produced pheromone that attracts conspecific C. ciliata males. Here, we discuss hypotheses regarding possible mechanisms involved in regulation of p-anisaldehyde production, including involvement of the compounds methyl p-anisate and p-methoxybenzoic acid, and the potential ecological function of p-anisaldehyde in C. ciliata.
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Trygve S. Aamlid John Ingar Øverland Geir Kjølberg Knudsen Jon Sæland Åge Susort Ove Hetland Kristine SundsdalSammendrag
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Hans Martin Hanslin Trygve S. Aamlid Ellen Johanne Svalheim Johannes Kollmann Geir Kjølberg Knudsen Harald BratliSammendrag
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Hans Martin Hanslin Trygve S. Aamlid Ellen Johanne Svalheim Geir Kjølberg Knudsen Johannes Kollmann Harald Bratli Jörgen WissmannSammendrag
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Trygve S. Aamlid Nils Kristian Aker Anders Øren Silja Valand Geir Kjølberg Knudsen Åge Susort Ove HetlandSammendrag
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Abdelhameed Elameen Cornelya Klutsch Ida Marie Bardalen Fløystad Geir Kjølberg Knudsen Marco Tasin Snorre Hagen Hans Geir EikenSammendrag
Knowledge about population genetic structure and dispersal capabilities is important for the development of targeted management strategies for agricultural pest species. The apple fruit moth, Argyresthia conjugella (Lepidoptera, Yponomeutidae), is a pre-dispersal seed predator. Larvae feed on rowanberries (Sorbus aucuparia), and when rowanberry seed production is low (i.e., inter-masting), the moth switches from laying eggs in rowanberries to apples (Malus domestica), resulting in devastating losses in apple crops. Using genetic methods, we investigated if this small moth expresses any local genetic structure, or alternatively if gene flow may be high within the Scandinavian Peninsula (~850.000 km2, 55o - 69o N). Genetic diversity was found to be high (n = 669, mean He = 0.71). For three out of ten tetranucleotide STRs, we detected heterozygote deficiency caused by null alleles, but tests showed little impact on the overall results. Genetic differentiation between the 28 sampling locations was very low (average FST = 0.016, P < 0.000). Surprisingly, we found that all individuals could be assigned to one of two non-geographic genetic clusters, and that a third, geographic cluster was found to be associated with 30% of the sampling locations, with weak but significant signals of isolation-by-distance. Conclusively, our findings suggest wind-aided dispersal and spatial synchrony of both sexes of the apple fruit moth over large areas and across very different climatic zones. We speculate that the species may recently have had two separate genetic origins caused by a genetic bottleneck after inter-masting, followed by rapid dispersal and homogenization of the gene pool across the landscape. We suggest further investigations of spatial genetic similarities and differences of the apple fruit moth at larger geographical scales, through life-stages, across inter-masting, and during attacks by the parasitoid wasp (Microgaster politus).
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Hans Martin Hanslin Trygve S. Aamlid Ellen Johanne Svalheim Geir Kjølberg Knudsen Harald Bratli Karin NormannSammendrag
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Trygve S. Aamlid Harald Bratli Hans Martin Hanslin Geir Kjølberg Knudsen Kristine Sundsdal Ellen Johanne SvalheimSammendrag
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Lars T. Havstad John I. Øverland Kristine Sundsdal Åge Susort Geir Kjølberg Knudsen Trond Olav PettersenSammendrag
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Lars T. Havstad Trond Gunnarstorp John I. Øverland Åge Susort Geir Kjølberg Knudsen Olav Langmyr Kristine SundsdalSammendrag
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Lars T. Havstad Trond Gunnarstorp John I. Øverland Åge Susort Geir Kjølberg Knudsen Olav Langmyr Kristine SundsdalSammendrag
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Trygve S. Aamlid Hans Martin Hanslin Ellen Johanne Svalheim H.K. Bratli Geir Kjølberg Knudsen Eivind NitterSammendrag
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Trygve S. Aamlid Ellen Johanne Svalheim Kristine Sundsdal Anne Steensohn Trond Olav Pettersen Ove Hetland Atle Beisland Åge Susort Gunnar Myhre Geir Kjølberg Knudsen Elise Krey PedersenSammendrag
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Olfaction is the most important sensory mechanism by which many insects interact with their environment and a wind tunnel is an excellent tool to study insect chemical ecology. Insects can locate point sources in a three-dimensional environment through the sensory interaction and sophisticated behavior. The quantification of this behavior is a key element in the development of new tools for pest control and decision support. A wind tunnel with a suitable flight section with laminar air flow, visual cues for in-flight feedback and a variety of options for the application of odors can be used to measure complex behaviour which subsequently may allow the identification of attractive or repellent odors, insect flight characteristics, visual-odor interactions and interactions between attractants and odors lingering as background odors in the environment. A wind tunnel holds the advantage of studying the odor mediated behavioural repertoire of an insect in a laboratory setting. Behavioural measures in a controlled setting provide the link between the insect physiology and field application. A wind tunnel must be a flexible tool and should easily support the changes to setup and hardware to fit different research questions. The major disadvantage to the wind tunnel setup described here, is the clean odor background which necessitates special attention when developing a synthetic volatile blend for field application.
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The apple fruit moth Argyresthia conjugella (Lepidoptera, Yponomeutidae) is a seed predator of rowan (Sorbus aucuparia) and is distributed in Europe and Asia. In Fennoscandia (Finland, Norway and Sweden), rowan fruit production is low every 2–4 years, and apple (Malus domestica) functions as an alternative host, resulting in economic loss in apple crops in inter-mast years. We have used Illumina MiSeq sequencing to identify a set of 19 novel tetra-nucleotide short tandem repeats (STRs) in Argyresthia conjugella. Such motifs are recommended for genetic monitoring, which may help to determine the eco-evolutionary processes acting on this pest insect. The 19 STRs were optimized and amplified into five multiplex PCR reactions. We tested individuals collected from Norway and Sweden (n = 64), and detected very high genetic variation (average 13.6 alleles, He = 0.75) compared to most other Lepidoptera species studied so far. Spatial genetic differentiation was low and gene flow was high in the test populations, although two non-spatial clusters could be detected. We conclude that this set of genetic markers may be a useful resource for population genetic monitoring of this economical important insect species.
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Nina Trandem Upendra Raj Bhattarai Isabelle Bueno Silva Karin Westrum Geir Kjølberg Knudsen Ingeborg KlingenSammendrag
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Planteparfyme og blomsterfelt får lusejegeren gulløye inn i kornåkeren viser forsøk frå NIBIO.
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Volatiles emitted by plants convey an array of information through different trophic levels. Animals such as host-seeking herbivores encounter plumes with filaments from both host and non-host plants. While studies showed a behavioral effect of non-host plants on herbivore host location, less information is available on how a searching insect herbivore perceives and flies upwind to a host-plant odor plume within a background of non-host volatiles. We hypothesized here that herbivorous insects in search of a host-plant can discriminate plumes of host and non-host plants and that the taxonomic relatedness of the non-host have an effect on finding the host. We also predicted that the ratio between certain plant volatiles is cognized as host-plant recognition cue by a receiver herbivorous insect. To verify these hypotheses we measured the wind tunnel response of the moth Argyresthia conjugella to the host plant rowan, to non-host plants taxonomically related (Rosaceae, apple and pear) or unrelated to the host (Pinaceae, spruce) and to binary combination of host and non-host plants. Volatiles were collected from all plant combinations and delivered to the test insect via an ultrasonic sprayer as an artificial plume. While the response to the rowan as a plant was not affected by the addition of any of the non-host plants, the attraction to the corresponding sprayed headspace decreased when pear or apple but not spruce were added to rowan. A similar result was measured toward the odor exiting a jar where freshly cut plant material of apple or pear or spruce was intermixed with rowan. Dose-response gas-chromatography coupled to electroantennography revealed the presence of seven field attractive and seven background non-attractive antennally active compounds. Although the abundance of field attractive and of some background volatiles decreased in all dual combinations in comparison with rowan alone, an increased amount of the background compounds (3E)-4,8-Dimethyl-1,3,7-nonatriene ((E)-DMNT) and (Z)-3-hexenyl acetate was found in the rowan-apple and rowan-pear but not in the rowan-spruce headspace. A higher ratio between the abundance of each field attractive component and that of (E)-DMNT and (Z)-3-hexenyl acetate was measured for rowan and rowan-spruce in contrast to rowan-pear and rowan-apple headspaces. Our result suggests that the ratio between field attractive and background antennaly active volatiles encodes host-plant recognition in our study system.
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The apple fruit moth (Argyresthia conjugella (A. conjugella)) in Norway was first identified as a pest in apple production in 1899. We here report the first genetic analysis of A. conjugella using molecular markers. Amplified fragment length polymorphism (AFLP) analysis was applied to 95 individuals from six different locations in the two most important apple-growing regions of Norway. Five AFLP primer combinations gave 410 clear polymorphic bands that distinguished all the individuals. Further genetic analysis using the Dice coefficient, Principal Coordinate analysis (PCO) and Bayesian analyses suggested clustering of the individuals into two main groups showing substantial genetic distance. Analysis of molecular variance (AMOVA) revealed greater variation among populations (77.94%) than within populations (22.06%) and significant and high FST values were determined between the two major regions (Distance = 230 km, FST = 0.780). AFLP analysis revealed low to moderate genetic diversity in our population sample from Norway (Average: 0.31 expected heterozygosity). The positive significant correlation between the geographic and the molecular data (r2 = 0.6700) indicate that genetic differences between the two major regions may be due to geographical barriers such as high mountain plateaus (Hardangervidda) in addition to isolation by distance (IBD).
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Geir Kjølberg KnudsenSammendrag
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Hege Johansen Marit Solum Geir Kjølberg Knudsen Eline Benestad Hågvar Hans Ragnar Norli Anders AakSammendrag
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Geir Kjølberg KnudsenSammendrag
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Geir Kjølberg KnudsenSammendrag
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Geir Kjølberg KnudsenSammendrag
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Geir Kjølberg KnudsenSammendrag
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The flight responses of 750 female Calliphora vicina Robineau-Desvoidy, 1830 (Diptera: Calliphoridae) are investigated in a wind tunnel bioassay. The attraction of C. vicina towards dead mice and seven different synthetic lures made from dimethyl trisulphide, mercaptoethanol and O-cresol is compared. Responses towards natural odours and the three-component synthetic kairomones depend on the flies' ovarian egg developmental status. The natural and three-component lures also induce similar age-dependent responses, although the dead mice lure yields a significantly higher attraction. Oriented flight increases with the number of chemicals in the synthetic kairomone; one-, two- and three-compound lures induce 13–25%, 32–43% and 62% attraction, respectively. Responses to one-component lures are not significantly influenced by egg developmental status, whereas blends of two or three components are. Attraction levels increase in a stepwise manner both across egg developmental categories and with the number of compounds. The results suggest that the attractiveness of synthetic kairomones is influenced not only by the blowflies' physiological state, but also by the complexity of the lure.
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Geir Kjølberg KnudsenSammendrag
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Geir Kjølberg KnudsenSammendrag
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Geir Kjølberg KnudsenSammendrag
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Geir Kjølberg KnudsenSammendrag
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Geir Kjølberg KnudsenSammendrag
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Geir Kjølberg KnudsenSammendrag
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Geir Kjølberg KnudsenSammendrag
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Herbivorous insects use information about volatile substances to select their host plants. The possibility that insects use these volatiles to assess the infection status of a host plant has rarely been tested. The assessment of host status via olfaction may allow a more successful allocation of time and energy towards the procurement of valuable resources for the offspring. We hypothesized that olfactory cues play a role in providing an herbivorous insect with information about the health status of a potential host plant. To test this hypothesis, we compared the attraction and oviposition response of the grapevine moth, Lobesia botrana, to healthy grapes, Vitis vinifera, with the response to grapes infected with a phytopathogenic fungus, Botrytis cinerea. The fungal infection elicited substantial reductions in both attraction from a distance and oviposition on the host. By preventing contact with the fruits, we found that volatiles from the infected grapes were the signal eliciting the observed behaviour. Experiments with a synthetic compound, 3-methyl-1-butanol, identified in the odour of infected grapes, confirmed the essential function of olfactory cues in this process, both in the laboratory and in the field. In our system, the avoidance of a diseased plant supported the preference performance hypothesis in L. botrana. Results are discussed in relation to the role of fungal volatiles in plant–insect relationships.
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Det hender at det er mark i eplene. Som oftest er det larven til rognebærmøll som er på ferde. Rognebærmøll er en liten sommerfugl som har fått navnet sitt fordi den har rogn som vertplante. I enkelte år er det lite bær på rogna og møllet må ta til takke med eple, som er nødproviant. Til våren 2010 ventes det svak blomstring hos rogn og det kan bli angrep i eple, i alle fall på Vestlandet. Situasjonen for Østlandet er litt annerledes. Prognoser om ventet fare for angrep av rognebærmøll i eple kan ikke lages før rogna blomstrer, vanligvis i slutten av mai, og da vil nøyaktige varsel bli sendt ut.
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Sammendrag
Larver av gullauger (Chrysoperla carnea) er ein av dei viktigaste nyttedyra i frukthagen. Tidlegare arbeid har vist at vaksne gullauger er tiltrukke av lukt frå mellom anna blomar. I forsøk har vi vist at lukt også stimulerar til egglegging hjå gullauger.
Forfattere
Miklós Tóth Ferenc Szentkirályi József Vuts Agostino Letardi Maria Rosaria Tabilio Gunnhild Jaastad Geir Kjølberg KnudsenSammendrag
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Geir Kjølberg Knudsen Maria Bengtsson Sverre Kobro Gunnhild Jaastad Trond Hofsvang Peter WitzgallSammendrag
Apple fruit moth Argyresthia conjugella is a specialist seed predator of rowan Sorbus aucuparia. Large-scale synchronous fluctuation of seed production in rowan (i.e. named masting) drives the apple fruit moth to seek alternative host plants such as apple, during years when rowan berries are not available for oviposition. The role of plant volatile compounds in the attraction of gravid apple fruit moth females is studied in a laboratory wind tunnel. Volatiles from rowan branches with green berries stimulate female moths to fly upwind and to land at the odour source. By contrast, females are not attracted to rowan branches without green berries, and they are not attracted to apple, demonstrating that the chemical stimulus from rowan berries is required for attraction. Attraction to synthetic compounds identified from rowan, anethole and 2-phenyl ethanol confirms the role of plant volatiles in host finding. These two compounds, however, show a discrepant behavioural effect in wind tunnel and field tests. Field traps baited with 2-phenyl ethanol capture female moths but anethole does not produce significant captures. Wind tunnel tests produce the opposite results: moths fly upwind towards the anethole lure, whereas 2-phenyl ethanol is not attractive at all. Wind tunnel attraction to 2-phenyl ethanol is achieved by adding odour from a rowan branch without berries, which is not attractive on its own. This finding demonstrates that interaction with the background odour contributes to the behavioural effect of plant volatile stimuli in the field.
Forfattere
Geir Kjølberg Knudsen Sverre Kobro Gunnhild Jaastad Trond Hofsvang M. Bengtsson P WitzgallSammendrag
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