Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2006
Forfattere
Ricardo Holgado Janet Rowe Stig Andersson Christer MagnussonSammendrag
Cereal cyst nematodes, Heterodera spp., are recognised throughout the world as economically important parasites of cereals. The virulence status on cereal cultivars differs between and within different species of the H. avenae-complex, and several pathotypes occur among them. A survey during 1995-2005 in Norway revealed that Heterodera spp. is common throughout the country. Studies in Norway have recorded H. filipjevi and also additional and possibly new species. A number of cereal cyst nematode populations from various regions of Norway, Sweden and the British Isles have been analysed using molecular, morphological and host range studies during the last three years. Fifteen populations, of the initial group of forty, are being studied more closely. Studies using isoelectric focusing and silver staining have detected divergent populations of H. avenae. The Swedish populations Ringsåsen seemed to be identical to a population found in Australia and the Swedish population Halland shows a protein profile separate from H. avenae. DNA studies are being used to determine if these populations are new species. An assortment of cereal cultivars, based on an international collection used for resistance testing, differentiates three groups, H. avenae (pathotypes Ha 11 and Ha 12), H. filipjevi (pathotype "West"), and a population from central Norway close to H. pratensis. Knowledge of the diversity of cereal cyst nematodes and their multiplication rates on their cereal hosts is of fundamental importance for efficient control strategies involving resistant cultivars. In Norway, management based on these parameters are in operation and have increased yields and profits to cereal farmers.
Forfattere
Ricardo HolgadoSammendrag
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Sammendrag
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Sammendrag
Methods for measuring prevalence of Neozygites floridana in a Tetranychus urticae population collected from strawberries were developed and compared. T. urticae were extracted from leaves using a soapy water solution (0.5 ml washing detergent : 8 l water) and then placed into 80% alcohol for use in methods 1 and 2. Method 1: N. floridana-sporulating T. urticae cadavers were observed and quantified under a compound microscope (40-80X). Method 2: Adult females were mounted in lactophenol cotton blue and observed for the presence or absence of N. floridana hyphal bodies under a microscope (200-400X). Method 3: Live T. urticae females were incubated at 25ºC and 75% RH and observed for mortality and N. floridana infection under a compound microscope (6.4-40X). Method 1 was the most time-efficient method and it also allows processing of samples as time permits. Method 2 quantified significantly higher fungal prevalence than method 1 and 3, but method 2 is not considered to be reliable because hyphal bodies are difficult to detect. No significant differences were found between methods 1 and 3.
Forfattere
Gudbrand Lien Ola Flaten Audun Korsæth K.D. Schumann J.W. Richardson Ragnar Eltun J. Brian HardakerSammendrag
Målet med denne studien var å jamføre risikoen for økologiske, integrerte og convensjonelle dyrkingssystem. Forsøksdata frå eit dyrkingssystem (1991-1999) på Austlandet vart brukte saman med budsjettal frå gardsbruk. Empirisk fordeling av nettoinntekt for ulike dyrkingssystem vart estimert ved hjelp av ein simuleringsmodell. Resultata syner at det økologiske systemet hadde størst variasjon i nettoinntekt, men med gjeldane tilskotsordningar og meirprisar for økologiske varer vert dette det mest økonomiske alternativet.
Forfattere
Linda Gordon Hjeljord Richard Meadow Annette Folkedal SchjøllSammendrag
Experiments were performed to determine the ability of the insect pathogenic hyphomycete, Metarhizium anisopliae, to germinate, grow and sporulate in the presence of Trichoderma atroviride. Trichoderma spp. includes mycoparasites commonly found in soil and used in biocontrol of plant diseases. When conidia of M. anisopliae and T. atroviride were coinoculated on agar media, T. atroviride overgrew M. anisopliae and prevented its establishment at temperatures from 6-30 oC. This effect was lessened when M. anisopliae and T. atroviride were inoculated at different points on the medium, giving the insect pathogen time to establish a colony and secrete antifungal metabolites. Although both fungi had growth optima at 25-30 oC, separately inoculated M. anisopliae was best able to compete with T. atroviride at temperatures " 18 oC, and the antibiosis zone was widest at 30oC. When M. anisopliae and T. atroviride were coinoculated onto black vine weevil larvae (Otiorhynchus sulcatus) at 20 oC, the ability of the insect pathogen to infect and kill the larvae and sporulate on the cadavers was not affected by the presence of T. atroviride conidia. These results indicate that while the virulence of M. anisopliae to the larvae was not reduced by T. atroviride, the ability of the insect pathogen to grow saprophytically and increase its inoculum could be reduced on substrates containing T. atroviride conidia.
Sammendrag
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Forfattere
Roy Browne Fabio Mascher Gabriela Golebiowska Ingerd Skow HofgaardSammendrag
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Sammendrag
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