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.
2021
Abstract
No abstract has been registered
Authors
Radoslav Cerovic Milica Fotiric-Aksic Milena Dordevic Mekjell MelandAbstract
No abstract has been registered
Authors
Radoslav Cerovic Milica Fotiric-Aksic Milena Dordevic Mekjell MelandAbstract
No abstract has been registered
Abstract
Aim It is generally assumed that the degree of resource specialization in herbivorous insects increases towards lower latitudes. However, latitudinal patterns in herbivore diet breadth at large spatial scales remain poorly understood. In this work, we investigated the drivers of latitudinal variation in lepidopteran ‘fundamental’ resource specialization, which we defined as the host breadth when not limited by interspecific interactions at the same trophic level. Location The Japanese archipelago (22°N–45°N), including hemiboreal, temperate and subtropical zones. Taxon Herbivorous butterflies. Methods Species-specific fundamental host breadth was calculated based on pooled host-use records. We investigated the latitudinal pattern and significant drivers of the degree of specialization in regional species pools at a 10-km grid level. As potential drivers, we focused on geography, current climate and diversity and body size of butterflies. Through Bayesian structural equation modelling, we investigated the complicated relationships between these variables and community-level resource specialization represented by three different indices of host breadth. Results We found that the fundamental resource specialization of butterfly communities increases towards higher latitudes. This pattern is contrary to the presumed general trend found in studies based on realized resource specialization within local communities. We found that the observed pattern is driven mainly by factors related to climate, butterfly diversity and body size in each community. Above all, annual mean temperature most strongly drove community-level fundamental host breadth of herbivorous butterflies. Main conclusions Our findings suggest that the fundamental resource specialization may show different latitudinal patterns from the conventional prediction based on knowledge of realized resource specialization. Our results emphasize the importance of the current climate as a major factor regulating butterfly morphology and fundamental host breadth, regardless of whether the impact is direct or indirect.
Abstract
The spruce bark beetle Ips typographus is the most damaging pest in European spruce forests and has caused great ecological and economic disturbances in recent years. Although native to Eurasia, I. typographus has been intercepted more than 200 times in North America and could establish there as an exotic pest if it can find suitable host trees. Using in vitro bioassays, we compared the preference of I. typographus for its coevolved historical host Norway spruce (Picea abies) and two non-coevolved (naïve) North American hosts: black spruce (Picea mariana) and white spruce (Picea glauca). Additionally, we tested how I. typographus responded to its own fungal associates (conspecific fungi) and to fungi vectored by the North American spruce beetle Dendroctonus rufipennis (allospecific fungi). All tested fungi were grown on both historical and naïve host bark media. In a four-choice Petri dish bioassay, I. typographus readily tunneled into bark medium from each of the three spruce species and showed no preference for the historical host over the naïve hosts. Additionally, the beetles showed a clear preference for bark media colonized by fungi and made longer tunnels in fungus-colonized media compared to fungus-free media. The preference for fungus-colonized media did not depend on whether the medium was colonized by conspecific or allospecific fungi. Furthermore, olfactometer bioassays demonstrated that beetles were strongly attracted toward volatiles emitted by both con- and allospecific fungi. Collectively, these results suggest that I. typographus could thrive in evolutionary naïve spruce hosts if it becomes established in North America. Also, I. typographus could probably form and maintain new associations with local allospecific fungi that might increase beetle fitness in naïve host trees.
Abstract
No abstract has been registered
Authors
Michel VerheulAbstract
No abstract has been registered
Authors
Tor MykingAbstract
No abstract has been registered
Authors
Christian PedersenAbstract
No abstract has been registered
Authors
Abdelhameed Elameen Svein Stueland Ralf Kristensen Rosa Ferreira Fristad Trude Vrålstad Ida SkaarAbstract
Saprolegnia parasitica is recognized as one of the most important oomycetes pests of salmon and trout species. The amplified fragment length polymorphism (AFLP) and method sequence data of the internal transcribed spacer (ITS) were used to study the genetic diversity and relationships of Saprolegnia spp. collected from Canada, Chile, Japan, Norway and Scotland. AFLP analysis of 37 Saprolegnia spp. isolates using six primer combinations gave a total of 163 clear polymorphic bands. Bayesian cluster analysis using genetic similarity divided the isolates into three main groups, suggesting that there are genetic relationships among the isolates. The unweighted pair group method with arithmetic mean (UPGMA) and principal coordinate analysis (PCO) confirmed the pattern of the cluster analyses. ITS analyses of 48 Saprolegnia sequences resulted in five well-defined clades. Analysis of molecular variance (AMOVA) revealed greater variation within countries (91.01%) than among countries (8.99%). We were able to distinguish the Saprolegnia isolates according to their species, ability to produce oogonia with and without long spines on the cysts and their ability to or not to cause mortality in salmonids. AFLP markers and ITS sequencing data obtained in the study, were found to be an efficient tool to characterize the genetic diversity and relationships of Saprolegnia spp. The comparison of AFLP analysis and ITS sequence data using the Mantel test showed a very high and significant correlation (r2 = 0.8317).