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
Authors
Leif Sundheim May Bente Brurberg Trond Hofsvang Christer Magnusson Trond Rafoss Brita Toppe Anne Marte Tronsmo Bjørn ØklandAbstract
No abstract has been registered
Abstract
Extensive timber imports represent potential introduction pathways for exotic bark beetles (Col: Scolytidae) that may pose ecological hazards and economical risks to native forests. One such species, Ips amitinus Eichh., has been intercepted several times at Norwegian ports of entry in the years since 2002, the year of the first Scandinavian record. Detection of overwintering individuals of I. amitinus at the timber storage site of import timber and preliminary results of a stepwise import model may suggest a high risk of establishment and spread in Norway spruce forests in Scandinavia.Using various modeling approaches, our goal is to reduce the risk of introduction, establishment, and spread of introduced bark beetles. Our objectives are to:model the processes of dispersal and establishment of arriving bark beetlesexplore to what extent an introduced species interacting with native Ips typographus L., the most dominant species in Norway spruce, will lead to stronger and more frequent outbreaks of I. typographusassess potential patterns of spread of newly established bark beetle species and the spatiotemporal outbreak dynamics resulting from interactions between native and introduced species; andadvise on the implications for forest industry and management.Here we present current efforts to model dispersal (objective 1). Dispersal patterns, and hence rates of establishment and spread, may vary considerably depending on dispersal behaviors of insects, such as directionality of movement and aggregation propensity. To assess underlying assumptions of dispersal models, we are using an individual-based model where traits governing dispersal are inherited with random mutations. Individual reproductive success is determined by resource availability and density-dependence in a simulated landscape governed by external forces (e.g., windfellings) and beetle activity (consumption of resources). Evolvable traits include straight line vs. random-walk flight paths and aggregation propensity.Model simulations show that the chance of successful reproduction is greatest for intermediate to high levels of directionality, and that directionality increases over time up to a certain point determined by the landscape features as well as other traits of the species. Assuming limited (local) information in a stochastic landscape, intermediate to high degree of flight directionality is selected for.
Authors
Bjørn ØklandAbstract
In recent years several forest insects have been recorded as newcomers or as more abundant than before towards northern latitudes and higher elevations in Norway. Such observations are from different groups of forest insect, including herbivorous geometrids, phloeophagous bark beetles and insects in cone seed .......
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Carl Gunnar Fossdal Ari M. Hietala Igor A. Yakovlev Halvor SolheimAbstract
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...
Abstract
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
Authors
Nadeem Yaqoob Carl Gunnar Fossdal Bao Dzung Diep Halvor SolheimAbstract
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.
Abstract
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....
Authors
Paal KrokeneAbstract
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.....