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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.

2026

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Abstract Background: Pesticides are used in greenhouse cultivation to control fungi and pests and to shape plant growth. This influences microbial communities and may increase the selective pressure for resistant species development. Antimicrobial resistance (AMR) is a growing global health challenge, and while AMR dispersal through soil and water is well studied, the role of bioaerosols as AMR vectors remains insufficiently explored. Objectives: To explore the link between chemical pesticide and the prevalence of AMR genes in aerosols from greenhouses using pesticides and those not using them. Methods: Forty-nine fullshift personal samples of inhalable dust were collected in eight greenhouses from 2021 and 2024. Five greenhouses used chemical pesticides and three did not. DNA was extracted and screened for the presence of 45 clinically relevant AMR genes using HT-qPCR. Results: Twenty of the 45 screened genes were detected. Greenhouses using pesticides showed significantly higher AMR gene levels than those not using chemicals. Several genes, particularly β-lactam and tetracycline resistance genes, occurred in high concentrations, including extreme values exceeding 60,000 gene copies/m³. This suggest that pesticide-using greenhouses may represent a greater risk for AMR dispersal. In contrast, greenhouses without chemical pesticide showed lower and more stable AMR gene levels. Factors other than pesticide application may also contribute, such as import of treated plants, soil and fertilizer materials, plant types or individual workers. Further research is needed to assess the health risks for greenhouse workers and to support the development of effective strategies for preventing and controlling AMR spread.

Abstract

Small, superficial rot spots occurring around lenticels postharvest on apple in Norway have not been identified but were assumed to be underdeveloped Neofabraea lesions. Fungal isolation from such spots on fruit from the 2022 season revealed both Neofabraea perennans and Ramularia spp., identified by B-tubulin and ITS sequencing, respectively. In the 2023 season, isolations were made from fruit with spots resembling dry lenticel spot caused by Ramularia mali. The aim of this study was to identify the Ramularia species associated with the postharvest fruit spots in Norway. Multiple gene regions of five Norwegian isolates (E20, E21 from 2022; 13,15 and 18 from 2023) and three reference isolates, R. mali, R. eucalypti, and R. collo-cygni, were sequenced and used for phylogenetic analysis. The Norwegian isolates were distinct from the included reference isolates, but clustered with other Ramularia species. Isolates 13, 18 and E21 clustered with Ramularia vizellae, while isolates 15 and E20 were most closely related to Ramularia phacae-frigidae. Isolate E20 was sequenced using the Oxford Nanopore Technologies MinION platform. Pathogenicity was assessed in a field inoculation study using isolate E21, resulting in typical spot development on inoculated fruit. Ramularia vizellae has previously been reported from dead apple leaf litter and other woody hosts in the Netherlands and Iran, while R. phacae-frigidae was originally described from Phaca frigida in Switzerland. Neither species has previously been reported in association with apple fruit spotting. While Ramularia mali has caused outbreaks on apple in several European countries, recent studies hypothesize that the symptoms may be caused by a species complex with regional variation. The present results identify candidate species contributing to this complex in Norway and highlight the need for further studies to improve species delimitation and pathogenicity.

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Accurate species identification is essential for conserving and managing plants that provide important ecosystem services and have ethnobotanical value. The Greyia tree genus ( G. sutherlandii , G. radlkoferi and G. flanaganii ) is endemic to South Africa and Eswatini, and certain genotypes have medicinal value for treating skin hyper‐pigmentation. However, distinguishing among species is difficult because of overlapping phenotypes and the limited resolution of standard DNA barcodes. To overcome these limitations, a robust molecular identification assay was developed using a two‐phase strategy. First, de novo SNP discovery using 3RAD sequencing identified 47,726 genome‐wide SNPs from two to three plants sampled from each species' core geographic range: G. radlkoferi in northern Limpopo, G. sutherlandii in eastern KwaZulu‐Natal, and G. flanaganii in the south‐eastern Eastern Cape. Principal component analysis and coancestry matrices revealed three discrete genetic clusters, supporting the recognition of the three species. Selecting a set of 200 SNPs with intermediate Fst values (0.2–0.5) resulted in optimal separation of the three clusters. This led to the final selection of a 23‐SNP panel that included five informative barcoding loci (ITS, trnL‐F , matK ). Second, the 23 SNPs were converted into allele‐specific fluorescent PCR assays (SNP Type) for genotyping on the BioMark HD platform. The panel was validated using genomic DNA from 17 individuals from the 3RAD population groups and successfully differentiated all three species. It was then applied to 73 trees sampled across a 1000‐km transect from the Eastern Cape to Limpopo. Genetic clustering (PCA, UPGMA and ADMIXTURE) assigned each tree to one of three species‐level groups matching their expected ranges. In a practical case study, the assay also identified the species origin of 33 Greyia trees of unknown provenance from production orchards. This study provides an efficient SNP‐based tool for accurate species identification, supporting conservation planning and the sustainable management of Greyia populations.

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Did you know that stairstep moss can be used as a sampler for air pollution? Researchers at NILU have collected this kind of moss on several occasions and examined it for metals and other pollutants.

2025

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The spatio-temporal evolution of woody plant lineages in the Holarctic is still understudied, limiting our understanding of evolutionary processes that promote higher diversity at higher latitudes in some lineages, which contradicts the latitudinal gradient hypothesis which predicts higher species richness in the tropics. Shrub willows (Salix subgenus Vetrix) comprise about 350 species of which many are adapted to arctic-alpine ecosystems and thus form an important element across the Holarctic region. In this study, we utilized RAD sequencing to estimate the spatio-temporal evolution of the Vetrix clade based on about 140 species covering most of its morphological and geographical diversity. The resolved phylogeny revealed four lineages: the Pan-Himalayan clade, the North American clade and two clades containing species from Eurasia. Widespread circumpolar species form a hybridogenetic grade between the Eurasian and North American clades. Our results confirm that shrub willows originated in the Tertiary, probably in Asia, and that diversification coincided with the climatic cooling in the Pleistocene. At least two radiations were observed, in the Pan Himalayas and in North America. Speciation was further shaped by migration and dispersal in Eurasia, likely accelerated by the uplift of mountain chains, the closure of the Turgai Strait and expansion of suitable habitats. The dated phylogeny revealed that speciation of arctic lineages predates adaptation to high latitudes, as also evident from the fossil record. Small wind-dispersed seeds enabled shrub willows to colonize the expanding arctic tundra regions in the Miocene and their recolonization after the LGM. Given the high observed number of polyploid species equally distributed in all clades and indications of genetic admixture, we assume that species diversity in shrub willows was additionally increased by hybridization and polyploidization.

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We studied the drivers of population-genetic structuring and genetic diversity in specialist parasites based on whole-genome resequencing data from 82 Echinophthirius horridus seal louse individuals sampled from 12 ecologically and behaviourally different phocine seal species, subspecies and populations across the Holarctic. We found that the main genetic disjunctions in E. horridus lice occur across seal host species and subspecies, with a further level of population subdivision emerging among host individuals within some populations. Endemic and relict landlocked seal (sub)species host the genetically most distinct louse populations, while lice associated with sympatric marine seals show signatures of occasional gene flow across hosts. Within the latter, the most extreme case is seen in the near-panmictic lice associated with northern European grey and harbour seals, which aggregate in shared rookeries and colonies. Although the louse and seal phylogenies were overall statistically significantly congruent, evidence for similar host shifts in the past is reflected in several conflicts in the phylogenetic trees of the lice and their hosts. Population-level mean heterozygosity and theta in seal lice varied considerably, and both measures of genetic variation were statistically significantly related to host population size. Taken together, our results support a non-adaptive model of parasite diversification, in which geographic and behavioural isolation among hosts drives parasite genetic differentiation, and genetic erosion in bottlenecked hosts cascades up to their specialist parasites. Our results provide new insights into processes that generate parasite diversity and trigger parallel losses of genetic diversity in endangered host–parasite systems.

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While social network analysis was originally developed for human sociology studies, it is also a valuable tool for characterizing behavioural aspects in many animal populations. For instance, social network analysis can be used for assessing the transmission of diseases or information within groups. Here, we describe co-occurrences and potential social associations of ringed seals, Pusa hispida saimensis, in Lake Saimaa, Finland, from 2016 to 2022, based on photoidentification data. Throughout seven successive moulting seasons (April to June), we identified 425 individuals, of which 178 had pairwise co-occurrences in altogether 185 dyads. These seals had a variable number of associates (up to 10), and co-occurrences were observed in 1–7 years. In general, observations of pairs or larger groups of seals (up to five individuals) were rare, and mainly occurred in the two most densely populated basins of the lake. Most of the group observations occurred on ice rather than on rocks. Overall, the fragmented nature of the lake system, site fidelity and moulting habitat availability are key factors that probably affect the observed co-occurrences. Most of the dyads were observed during only one year, which may indicate social tolerance while using the same moulting site. However, 21 dyads were observed during multiple moulting seasons, with some at different sites separated by up to 3 km in different years, suggesting the existence of actual long-lasting associations. Our study represents the first description of co-occurrences and potential social associations in the endangered Saimaa ringed seal. These results can be used for designing and implementing mitigation strategies in case of unforeseen and sudden changes in the environment, such as a disease outbreak.