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.
2012
Forfattere
Hugo Germain Denis Lachance Gervais Pelletier Carl Gunnar Fossdal Halvor Solheim Armand SeguinSammendrag
A 1149 bp genomic fragment corresponding to the 5' non-coding region of the PgD1 (Picea glauca Defensin 1) gene was cloned, characterized, and compared with all Arabidopsis thaliana defensin promoters. The cloned fragment was found to contain several motifs specific to defence or hormonal response, including a motif involved in the methyl jasmonate reponse, a fungal elicitor responsive element, and TC-rich repeat cis-acting element involved in defence and stress responsiveness. A functional analysis of the PgD1 promoter was performed using the uidA (GUS) reporter system in stably transformed Arabidopsis and white spruce plants. The PgD1 promoter was responsive to jasmonic acid (JA), to infection by fungus and to wounding. In transgenic spruce embryos, GUS staining was clearly restricted to the shoot apical meristem. In Arabidopsis, faint GUS coloration was observed in leaves and flowers and a strong blue colour was observed in guard cells and trichomes. Transgenic Arabidopsis plants expressing the PgD1::GUS construct were also infiltrated with the hemibiotrophic pathogen Pseudomonas syringae pv. tomato DC3000. It caused a suppression of defensin expression probably resulting from the antagonistic relationship between the pathogen-stimulated salicylic acid pathway and the jasmonic acid pathway. It is therefore concluded that the PgD1 promoter fragment cloned appears to contain most if not all the elements for proper PgD1 expression and that these elements are also recognized in Arabidopsis despite the phylogenetic and evolutionary differences that separates them.
Forfattere
Rune Andreassen Julia Schregel Alexander Kopatz Camilla Tobiassen Per Knappskog Snorre Hagen Oddmund Kleven Michael Schneider Ilpo Kojola Jouni Aspi Alexander M. Rykov Konstantin F. Tirronen Pjotr I. Danilov Hans Geir EikenSammendrag
Det er ikke registrert sammendrag
Forfattere
Lise AanensenSammendrag
Rovdyr antas i mange områder å være den viktigste årsaken til tap av sau på utmarksbeite, og de siste årene har man satt i gang flere tiltak for å redusere risikoen for rovdyrskade på sau. I denne artikkelen presenteres resultater fra et prosjekt hvor en blant annet studerte effekten av rovdyrsikre elektriske gjerder på lammetapet i beitesesongen. Prosjektet viser at rovdyrsikker inngjerding reduserer lammetapet betraktelig hos de besetningene som har gode driftsrutiner fra før av. Utslagsgivende faktorer er: • at dyrene er på beiter med rovdyrsikker inngjerding gjennom hele beitesesongen • gode rutiner når det gjelder tilsyn av dyr og vurdering av beitekvalitet • gode rutiner for tilsyn og vedlikehold av gjerdeanlegget • gode rutiner for forebyggende parasittbehandling • medlemskap i Sauekontrollen. Rovdyrsikre gjerder kan aldri bli 100 % sikre, men kan de begrense rovdyrskadene med 80-90 % er det meget bra.
Sammendrag
Økt årlig nedbør og hyppigere episoder med kraftig nedbør ventes i Norge som en følge av klimaendringer. I denne artikkelen vises resultater fra studier av hvordan nedbør påvirker mengden av fekale indikatorbakterier og parasittiske protozoer (Cryptosporidium and Giardia) som renner av fra ulike beiteområder for hest, storfe og småfe. Studiene illustrerer hvordan økt nedbør kan øke faren for at tarmbakterier og potensielt patogene mikroorganismer fra beiteområder for husdyr tilføres overflatevann. Gode tiltak mot forurensing i nedbørfeltet og god beskyttelse av sårbare vannkilder, samt god drikkevannsbehandling er viktig i dag, og vil være enda viktigere under fremtidige klimatiske forhold.
Forfattere
Kyrre Linné Kausrud Bjørn Økland Olav Skarpaas Jean-Claude Grégoire Nadir Erbilgin Nils Christian StensethSammendrag
In recent decades we have seen rapid and co-occurring changes in landscape structure, species distributions and even climate as consequences of human activity. Such changes affect the dynamics of the interaction between major forest pest species, such as bark beetles (Coleoptera: Curculionidae, Scolytinae), and their host trees. Normally breeding mostly in broken or severely stressed spruce; at high population densities some bark beetle species can colonise and kill healthy trees on scales ranging from single trees in a stand to multi-annual landscape-wide outbreaks. In Eurasia, the largest outbreaks are caused by the spruce bark beetle, Ips typographus (Linnaeus), which is common and shares a wide distribution with its main host, Norway spruce (Picea abies Karst.). A large literature is now available, from which this review aims to synthesize research relevant for the population dynamics of I. typographus and co-occurring species under changing conditions. We find that spruce bark beetle population dynamics tend to be metastable, but that mixed-species and age-heterogeneous forests with good site-matching tend to be less susceptible to large-scale outbreaks. While large accumulations of logs should be removed and/or debarked before the next swarming period, intensive removal of all coarse dead wood may be counterproductive, as it reduces the diversity of predators that in some areas may play a role in keeping I. typographus populations below the outbreak threshold, and sanitary logging frequently causes edge effects and root damage, reducing the resistance of remaining trees. It is very hard to predict the outcome of interspecific interactions due to invading beetle species or I. typographus establishing outside its current range, as they can be of varying sign and strength and may fluctuate depending on environmental factors and population phase. Most research indicates that beetle outbreaks will increase in frequency and magnitude as temperature, wind speed and precipitation variability increases, and that mitigating forestry practices should be adopted as soon as possible considering the time lags involved.
Sammendrag
Abstract Due to difficulties in tracing engineered nanoparticles (ENPs) in complex media, there are few data on the exposure of soil biota to ENPs. This study used neutron activated cobalt (Co NPs) and silver (Ag NPs) nanoparticles, as well as soluble cobalt and silver salts, to assess the uptake, excretion and biodistribution in the earthworm Eisenia fetida. Concentrations of cobalt in worms after four weeks exposure reached 88% and 69% of the Co ions and Co NPs concentrations in food, respectively, while corresponding values for Ag ions and Ag NPs were 2.3% and 0.4%. Both Ag ions and Ag NPs in earthworms were excreted rapidly, while only 32% of the cobalt accumulated from Co ions and Co NPs were excreted within four months. High accumulation of cobalt was found in blood and in the digestive tract. Metal characterization in the exposure medium was assessed by sequential extraction and ultrafiltration. The Co NPs showed significant dissolution and release of ions, while Ag ions and particularly Ag NPs were more inert.
Forfattere
Terje Gobakken Erik Næsset Ross F. Nelson Ole Martin Bollandsås Timothy G. Gregoire Göran Ståhl Sören Holm Hans Ole Ørka Rasmus AstrupSammendrag
In this paper two sampling and estimation strategies for regional forestinventory were investigated in detail and results were presented for various geographical scales. Airbornelaser scanner (ALS) data were acquired to augment data from a systematic sample of NationalForestInventory (NFI) ground plots in HedmarkCounty, Norway (27,390 km2). Approximately 50% of the NFI fieldplots were covered by the systematic ALS sample of 53 parallel flight lines spaced 6 km apart. The area was stratified into eight cover classes and independent log-transformed regression models were developed for each class to predict total above-ground dry biomass (AGB). The two laser-ground estimation strategies tested were a model-dependent (MD), two-phase approach that rests on the assumption that the predictive models are correctly specified, and a model-assisted (MA) approach with a two-stage probability sampling design which utilizes design-unbiased estimators. ALS AGB estimates were reported by land cover class and compared to the NFI ground estimates. The ALS-based MA and MD mean estimates differed from the NFI AGB estimates by about 2% and 8%, respectively, for the entire County. At the county level the smallest estimated standard error (SE) for the estimates was obtained using the field data alone. However, the SEs calculated from field and ALS data were based on unequal numbers of ground plots. When considering only the NFI plots in the ALS strips, the smallest SEs were obtained using the MD framework. However, we also illustrated the sensitivity of the estimates of applying different plausible models. All the applied estimators assumed simple random sampling while the selection of flight lines as well as ground plots followed a systematic design. Thus, the estimates of SE were most likely conservative. Simulated sampling undertaken in a parallel research effort suggests that the overestimation of the SEs was probably much larger for the ALS-based estimates compared to the NFI estimates. ALS-based estimates were also derived for sub-county political units and thereby demonstrated how limited sample sizes affect the standard error of the biomass estimates.
Forfattere
Merete Dees Leslie A WannerSammendrag
Common scab (CS) is an important disease and quality problem in potato crops worldwide. CS degrades the appearance of the potato tubers, thereby diminishing market value. Knowledge of CS has expanded considerably over recent years, enabling improved detection of the causal pathogens and increased understanding of mechanisms of pathogenicity, and providing potential methods of modulating pathogen response for disease resistance. However, effective control of this disease remains elusive, and will require increased understanding of both the host and the pathogen. Traditional control strategies such as irrigation and reduced soil pH are not sufficient and often fail. Optimizing environmental conditions for reduction of CS can also lead to favorable conditions for other diseases. The most desirable control method would be disease-resistant potato cultivars. However, no currently available commercial potato cultivar has been shown to be completely resistant to CS. In this review, we provide an overview of potato CS caused by plant pathogenic Streptomyces species, recent research on mechanisms and management of the disease, and knowledge gaps that limit successful control of this ubiquitous and troublesome disease.
Sammendrag
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.
Sammendrag
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.