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.
2023
Authors
Dario Isidro Ojeda Alayon Max John Robert L. Hammond Riitta Savolainen Kari Vepsäläinen Torstein KvammeAbstract
The Formicoxenus genus-group comprises six genera within the tribe Crematogastrini. The group is well known for repeated evolution of social parasitism among closely related taxa and cold-adapted species with large distribution ranges in the Nearctic and Palearctic regions. Previous analyses based on nuclear markers (ultraconserved elements, UCEs) and mitochondrial genes suggest close relationship between Formicoxenus Mayr, 1855, Leptothorax Mayr, 1855 and Harpagoxenus Forel, 1893. However, scant sampling has limited phylogenetic assessment of these genera. Also, previous phylogeographic analyses of L. acervorum (Fabricius, 1793) have been limited to its West-Palearctic range of distribution, which has provided a narrow view on recolonization, population structure and existing refugia of the species. Here, we inferred the phylogenenetic history of genera within the Formicoxenus genus-group and reconstructed the phylogeography of L. acervorum with more extensive sampling. We employed three datasets, one data set consisting of whole mitochondrial genomes, and two data sets of sequences of the COI-5P (658 bp) with different number of specimens. The topologies of previous nuclear and our inferences based on mitochondrial genomes were overall congruent. Further, Formicoxenus may not be monophyletic. We found several monophyletic lineages that do not correspond to the current species described within Leptothorax, especially in the Nearctic region. We identified a monophyletic L. acervorum lineage that comprises both Nearctic and Palearctic locations. The most recent expansion within L. acervorum probably occurred within the last 0.5 Ma with isolated populations predating the Last Glacial Maximum (LGM), which are localized in at least two refugial areas (Pyrenean and Northern plateau) in the Iberian Peninsula. The patterns recovered suggest a shared glacial refugium in the Iberian Peninsula with cold-adapted trees that currently share high-altitude environments in this region.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Igor Koloniuk Jana Fránová Jaroslava Pribylová Tatiana Sarkisova Josef Špak Jiunn Luh Tan Rostislav Zemek Radek Cmejla Martina Rejlová Lucie Valentová Jiri Sedlák Jan Holub Jan Skalik Dag-Ragnar Blystad Bijaya Sapkota Zhibo HamborgAbstract
No abstract has been registered
Abstract
After fungal decay experiments chemical characterisation of the wood is often a routine and several methodological approaches are available. In this study, we tested if simultaneous thermal analysis (STA) is a valid alternative to traditional wet chemical methods since STA allows significantly smaller sample size and faster analysis. Three model fungi including the brown rot fungi Rhodonia placenta and Gloeophyllum trabeum and the white rot fungus Trametes versicolor were employed in the study using Norway spruce as substrate. The experiment was harvested after 10, 20 and 52 weeks. At each harvest interval, aliquots of the material were characterized by STA and wet chemical methods. The results validated that STA can be effectively used to estimate cell wall composition of brown rot depolymerised wood. However, STA slightly overestimated cellulose at brown rot decay above 50%. The method was not verified for simultaneous white rot because STA only estimated hemicellulose correctly compared to the wet chemical method. Hence, STA is considered suitable for brown rot fungi below 50% mass loss but not for simultaneous white rot because STA did not estimate cellulose and lignin correctly.
Authors
Xiaoyan Ma Junhua Bao Jinwei Li Xi Cheng Muhammad Mobeen Tahir Meizi Liu Xian Lu Min-Rui Wang Zhibo Hamborg Dong ZhangAbstract
No abstract has been registered
Abstract
Weeds affect crop yield and quality due to competition for resources. In order to reduce the risk of yield losses due to weeds, herbicides or non-chemical measures are applied. Weeds, especially creeping perennial species, are generally distributed in patches within arable fields. Hence, instead of applying control measures uniformly, precision weeding or site-specific weed management (SSWM) is highly recommended. Unmanned aerial vehicle (UAV) imaging is known for wide area coverage and flexible operation frequency, making it a potential solution to generate weed maps at a reasonable cost. Efficient weed mapping algorithms need to be developed together with UAV imagery to facilitate SSWM. Different machine learning (ML) approaches have been developed for image-based weed mapping, either classical ML models or the more up-to-date deep learning (DL) models taking full advantage of parallel computation on a GPU (graphics processing unit). Attention-based transformer DL models, which have seen a recent boom, are expected to overtake classical convolutional neural network (CNN) DL models. This inspired us to develop a transformer DL model for segmenting weeds, cereal crops, and ‘other’ in low-resolution RGB UAV imagery (about 33 mm ground sampling distance, g.s.d.) captured after the cereal crop had turned yellow. Images were acquired during three years in 15 fields with three cereal species (Triticum aestivum, Hordeum vulgare, and Avena sativa) and various weed flora dominated by creeping perennials (mainly Cirsium arvense and Elymus repens). The performance of our transformer model, 1Dtransformer, was evaluated through comparison with a classical DL model, 1DCNN, and two classical ML methods, i.e., random forest (RF) and k-nearest neighbor (KNN). The transformer model showed the best performance with an overall accuracy of 98.694% on pixels set aside for validation. It also agreed best and relatively well with ground reference data on total weed coverage, R2 = 0.598. In this study, we showed the outstanding performance and robustness of a 1Dtransformer model for weed mapping based on UAV imagery for the first time. The model can be used to obtain weed maps in cereals fields known to be infested by perennial weeds. These maps can be used as basis for the generation of prescription maps for SSWM, either pre-harvest, post-harvest, or in the next crop, by applying herbicides or non-chemical measures.
Authors
Heidi Udnes Aamot Hesam Mousavi Jafar Razzaghian Guro Brodal Michael Sulyok Rudolf Krska Simon G. Edwards Ingerd Skow HofgaardAbstract
In Norway, high levels of mycotoxins are occasionally observed in oat grain lots, and this cause problems for growers, livestock producers and the food and feed industries. Mycotoxins of primary concern are deoxynivalenol (DON) produced by Fusarium graminearum and HT2- and T2-toxins (HT2+T2) produced by Fusarium langsethiae. Although effort has been made to understand the epidemiology of F. langsethiae in oats, this is still not fully understood. In the present study, we aimed to increase our understanding of the F. langsethiae – oat interaction. Resistance to F. langsethiae was studied in three oat varieties after inoculation at early (booting, heading, flowering) or late (flowering, milk, dough) growth stages in greenhouse experiments. The oat varieties had previously shown different levels of resistance to F. graminearum: Odal, Vinger (both moderately resistant), and Belinda (susceptible). The levels of F. langsethiae DNA and HT2+T2 in harvested grain were measured, and differences in aggressiveness (measured as the level of F. langsethiae DNA in grain) between F. langsethiae isolates were observed. Substantial levels of F. langsethiae DNA and HT2+T2 were detected in grain harvested from oats that had been spray-inoculated at heading or later growth stages, suggesting that oats are susceptible to F. langsethiae from heading and onwards. Vinger had a moderate resistance to F. langsethiae/HT2+T2, whereas Odal and Belinda were relatively susceptible. We observed that late inoculations resulted in relatively higher levels of trichothecene A metabolites other than HT2+T2 (mostly glycosylated HT-2, and smaller amounts of some other metabolites) in harvested grain, which indicate that infections close to harvest may pose a further risk to food and feed safety.
Abstract
No abstract has been registered
Authors
Hadush Tsehaye Beyene Leif Sundheim Arne Tronsmo May Bente Brurberg Dereje Assefa Anne Marte TronsmoAbstract
No abstract has been registered