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.
1997
Forfattere
Nina Elisabeth Nagy Kirsten Bjørklund Holven Norbert Roos Haruki Senoo Naosuke Kojima Kaare Reidar Norum Rune BlomhoffSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Twenty-five year old Norway spruce trees (Picea abies) were inoculated with four blue-stain fungi. Each tree was inoculated three times with each fungus and three times with sterile agar as a control, giving a total of 15 inoculations per tree. There was little variation in the extent of phloem necrosis produced in response to the different fungi, but five weeks after inoculation necrosis induced by Ceratocystis polonica and Ambrosiella sp. were significantly longer than those for the other fungi. At the same time, C. polonica had induced sapwood desicc-ation twice as deeply into the wood as any other fungus.Hyphal growth of the fungi into phloem and sapwood followed the same pattern as necrosis length and desiccation depth. Five weeks after inoculation C. polonica had penetrated phloem and sapwood further than any other fungus. It grew slower than the other fungi in both tissues the first week after inoculation, but the four following weeks it grew faster than all other fungi.
Forfattere
Nina JohansenSammendrag
Developmental time and survival of eggs, larvae, pupae and adult females of the cabbage moth, Mamestra brassicae (L.) (Lepidoptera: Noctuidae) were investigated at different temperatures within the range of 5 to 23oC. In addition, the influence of temperature during the larval period on the weight of the succeeding pupae was studied, as well as the effect of temperature on fecundity of adult females. The lower developmental thresholds (Tb) and thermal requirement (DD) were established for all developmental stages and the larval instars using linear regression analysis. Tb and DD were 8.6°C and 75 degree-days for eggs, 5.4°C and 496 degree-days for the total larval period, 7.2°C and 304 degree-days for pupae, and 5.0°C and 56 degree-days for adult females, respectively. Pupal mortality was low at all temperatures. The survival of eggs and larvae was highest at 18oC, whereas mortality was 100% at 8.5oC. Larval mortality was highest in the first instar and decreased with increasing age. Pupae gained the highest weight when the larvae were reared at 18oC, and decreased with declining temperature. Temperature had no significant effect on total fecundity or fertility. Fecundity was basically unimodal distributed at all temperatures. At low temperatures the egg deposition period was markedly prolonged.
Forfattere
Nina JohansenSammendrag
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Forfattere
Paal KrokeneSammendrag
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Forfattere
Karl ThunesSammendrag
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1996
Forfattere
Guro BrodalSammendrag
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Forfattere
Guro BrodalSammendrag
Det er ikke registrert sammendrag
Forfattere
Nina JohansenSammendrag
Studies on the population dynamic of Mamestra brassicae (L.) (Lepidoptera: Noctuidae) were conducted during 1988-1992 in order to improve forecasting and control. The influence of temperature on development, fecundity and survival were investigated in climatic chambers, and lower developmental thresholds and thermal requirements were established for the preoviposition period and the immature stages. Pheromone traps were tested in cabbage fields at 5 locations in south-eastern Norway during 1989-1991. The trap catches were low at all locations and years, and the traps could therefore not be recommended for practical monitoring. A degree-day model for prediction of favourable times for assessment of infestation level and insecticide application was developed, validated and implemented. Mortality in the immature stages, and larval dispersal, was investigated in the laboratory and in the field. Highest mortality was found in first instar larvae and in hibernating pupae. The mortality in first instar larvae was probably caused by failure to locate and establish feeding sites and predation, whereas the winter loss probably was caused by unfavourable weather conditions. Life tables for five generations of a natural population of M. brassicae on white cabbage in Ås during 1988-1992 was constructed and analysed. Generation survival was very low, and the key factor was mortality in small larvae. The stage specific mortality appeared to be mainly density-independent. Parasitoids and pathogens were of little importance in controlling the M. brassicae population, although they were more or less persistently present throughout the experimental period. Trichogramma semblidis (Aurivillius) (Trichogrammatidae) was reared from eggs, and Microplitis mediator (Haliday) and Aleiodes (Aleiodes) sp., both Braconidae, were reared from larvae. Erynia virescens (Entomophtorales) was identified in medium and large larvae. Implications of the results in this study for integrated pest management is discussed, and management tactics are proposed.