Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2008
Forfattere
Carl Gunnar Fossdal Ari M. Hietala Igor A. Yakovlev Halvor SolheimSammendrag
The root-rot causing fungus Heterobasidion annosum sensu lato is the most devastating pathogen of conifers in Europe. This pathogen enters Norway spruce through the roots and can colonize the tree from within, growing as a saprophyte when established within the dead heartwood and acting as a necrotroph when in contact with living host tissue. Despite the high incidence of damage, trees have defences against this pathogen in the bark and living wood. Furthermore, spruce has a defense against internal attack by forming a reaction zone, in this case the host defense is directed inwardly by the still living sapwood toward the central colonized heartwood. We have studied the host responses to infection in Norway spruce clones at the transcriptional level and found that the speed of recognition and that spatial defense signalling appears to be the hallmarks of trees with high degree of resistance...
Sammendrag
The Norwegian records of the ant Camponotus vagus (Scopoli, 1763) are presented and the distribution is discussed. Information on its biology and habitat choice is given. C. vagus is an overlooked species that must be considered rare in Norway
Forfattere
Nadeem Yaqoob Carl Gunnar Fossdal Bao Dzung Diep Halvor SolheimSammendrag
Due to the great economic losses caused by the root and butt-rot pathogen Heterobasidion annosum, developments of efficient control measures are warranted. H. annosum a necrotroph colonize the Norway spruce from inside and is responsible of 10-13 millions Euros losses in Norway alone. Considerable clonal variation has been recorded for Norway spruce in resistance towards H. annosum, but the defence mechanisms contributing to host resistance remain poorly understood. The recent genome sequencing of Populus has made the genus a model to facilitate tree genetics. Genome-wide transcript profiling of Populus tremula upon pathogen attack will now be used, and homologues of Norway spruce genes to defence genes up-regulated in Populus will be identified. Populus-Phellinus tremula pathosystem is selected as P. tremula behaves like H. annosum.
Sammendrag
The European pine sawfly Neodiprion sertifer is a widely distributed defoliator of pines that can cause substantial growth losses over extensive areas. It attacks most species of twoneedle pines in its distribution area, and have occasional short-lived outbreaks that may cover up to 200.000 ha. In Norway we have had outbreak populations in the eastern part of the country since 2004, and in an ongoing research project we are evaluating aerial application of the Neodiprion sertifer nuclear polyhedrosis virus (NsNPV) to control Neodiprion sertifer....
Forfattere
Paal KrokeneSammendrag
Combined bark beetle-fungus attacks are a key factor in conifer ecosystems in the Northern Hemisphere, where they regularly cause massive tree mortality. Central to the success of the bark beetle-fungus complex is the fact that bark beetles are among the few insects that are capable of breaching the potent anatomical and chemical defenses of healthy tree stems.....
Sammendrag
Seed production in Norway spruce (Picea abies) seed orchards may be severely reduced by insects attacking cones and seeds. Insects in several orders and genera are responsible for the damage, and at present there are no effective and environmentally acceptable control options. Studies in Sweden have shown promising results with spraying Bt (Bacillus thuringiensis var. kurstaki x aizawai) against species of Lepidoptera, but for other pests other control methods must be developed....
Sammendrag
Pine Wood Nematode (PWN, Bursaphelenchus xylophilus) is the causal organism of Pine Wilt Disease (PWD), the worst forest pest of Japan. In Europe PWN is known to exist in Portugal. The Norwegian Food Safety Authority (Mattilsynet) is concerned about the plant health risks and the consequences to the society if PWN should establish in Norway. Mattilsynet needs a scientific assessment of the proposed measures in a contingency plan for PWN. Mattilsynet also needs the risks connected with recent spread of PWN in Portugal to be evaluated before possible changes can be made in the current phytosanitary policy of Norway. On this background Mattilsynet requested a pest risk assessment of PWN from the Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet, VKM). To answer the request, VKM commissioned a draft pest risk assessment report from the Norwegian Institute for Agricultural Sciences and Environmental Research (Bioforsk). A working group appointed by VKM’s Panel on Plant Health (Panel 9) has been involved during Bioforsk’s work on the report. VKM’s Panel 9 has used the report as a basis for VKM’s opinion. The current document answers Part 1 of Mattilsynet’s request, and was adopted by Panel 9 on a meeting 3rd September 2008. VKM’s Panel 9 gives the following main conclusions of the risk assessment: The PRA area of this assessment is Norway. PWN is not known to occur in Norway. With present trade pattern the probability of entry of PWN into Norway is expected to be high. The most probable pathway for entry of PWN into Norway would be wood packaging material (WPM). The probability that PWN will establish and spread in Norway is considered as high. With regard to the so-called Pest Free Areas (PFAs) of Portugal, the criteria given in ISPM No. 4 (FAO 1995) for establishing and maintaining PFAs have not been met, and the data available is not sufficient to confirm the existence of PFAs. Acceptance of untreated conifer wood from all parts of Portugal will result in a very high probability of entry and a high probability of establishment and spread of PWN and its vector to Norway. Uncertainty factors: To the best of our knowledge PWN is absent from the PRA area. The beetle M. sutor is regarded as a potential vector or PWN, but this has so far not been demonstrated in nature. The currently low vector densities may retard establishment of the PWN and PWD, but it will probably not stop establishment in a longer perspective. Lack of information on the dynamics of PWN populations in cool climates complicates estimates of the spread of the nematode and PWD. Custom routines may fail in their detection of PWN. Import of a seemingly harmless material might therefore pose an unknown risk. WPM follows consignments of all kinds and is a good example of a hazardous material, which often escapes plant health inspections. Detailed assessments of economic consequences of a possible establishment and spread of PWN in Norway, the effects of global warming and other climate changes on the probability for PWD outbreaks, and the effect of possible phytosanitary measures, will be given in Part 2.
Sammendrag
Tree-killing bark beetles conquer healthy trees by means of pheromone mediated mass-attacks. The initial attackers select trees through a process of random landing and processing of tactile and short-range chemical stimuli. Inside acceptable hosts they produce aggregation pheromones that attract additional attackers. In a recent field experiment we induced defense responses in 60-year-old Norway spruce trees and monitored colonization by the spruce bark beetle Ips typographus. Induced stem sections had significantly less beetle colonization than control sections, with shorter parental galleries and fewer eggs deposited. In addition, fewer beetles were attracted to beetles tunnelling in induced bark. This reduced ability to attract conspecifics suggests that induced host defenses interfere with beetle pheromone production or emission. The mechanisms responsible for this are unknown, but may involve emission of volatile terpenes such as (E)-b-farnesene and linalool, which have been shown to increase up to 100-fold in induced Norway spruce trees. These compounds have been reported to attract natural enemies of herbivores or repel herbivores directly in other conifer-insect interactions.
Forfattere
Halvor SolheimSammendrag
Climate change may influence in a worse manner for the forests in various ways. Some pathogens may increase their importance and new may arrive. Root and butt rot is the most serious problem in Norway spruce forests. In mean more than every fourth tree is infested when harvested. Dryer summers may give increased frequency of rot caused by Heterobasidion. In addition Armillaria spp may gain change in weather condition both as root rot and in connection with a syndrome together with drought and bark beetles. More unstable winter climate may give increase of Gremmeniella attack on Scots pine. Longer and warmer growth season will give many pathogens better condition. Among those is Ophiostoma novo-ulmi causing Dutch elm disease which is lasting in south eastern Norway at a rather low frequency and the volume of elm is not lower than for 15 years ago. In which way the newly introduced Chalara fraxinea will behave in Norway is uncertain, but a better growth season will probably also influence on the possibility to be spread all over Norway where ash are growing.
Forfattere
Nenad Kea Halvor SolheimSammendrag
No abstract has been registered