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.
2016
Abstract
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Abstract
The two-spotted spider mite, Tetranychus urticae, is a serious pest of numerous crops worldwide. Sustainable management solutions for T. urticae include predators and entomopathogens. Neozygites floridana is a naturally occurring obligate fungal pathogen of T. urticae and can cause declines in T. urticae populations. The purpose of this study was to determine whether releasing the predatory mite Phytoseiulus persimilis into T. urticae populations has the potential to increase transmission of N. floridana and accelerate the development of an epizootic. This is the first study quantifying the effect of P. persimilis on transmission of N. floridana to T. urticae in a controlled microcosm study. Our results show that introducing P. persimilis into T. urticae, populations increased the proportion of T. urticae infected with N. floridana. By the final sampling occasion, the number of T. urticae in the treatment with both the predator and the pathogen had declined to zero in both experiments, while in the fungus-only treatment T. urticae populations still persisted. We suggest that releasing P. persimilis into crops in which N. floridana is naturally present has the potential to improve spider mite control more than through predation alone.
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No abstract has been registered
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No abstract has been registered
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No abstract has been registered
Abstract
Glucosinolates are plant secondary metabolites with important roles in plant defence against pathogens and pests and are also known for their health benefits. Understanding how environmental factors affect the level and composition of glucosinolates is therefore of importance in the perspective of climate change. In this study we analysed glucosinolates in Arabidopsis thaliana accessions when grown at constant standard (21 °C), moderate (15 °C) and low (9 °C) temperatures during three generations. In most of the tested accessions moderate and pronounced chilling temperatures led to higher levels of glucosinolates, especially aliphatic glucosinolates. Which temperature yielded the highest glucosinolate levels was accession-dependent. Transcriptional profiling revealed also accession-specific gene responses, but only a limited correlation between changes in glucosinolate-related gene expression and glucosinolate levels. Different growth temperatures in one generation did not consistently affect glucosinolate composition in subsequent generations, hence a clear transgenerational effect of temperature on glucosinolates was not observed.
Authors
Lars T. HavstadAbstract
No abstract has been registered
Authors
Lars T. HavstadAbstract
No abstract has been registered
Abstract
A controlled climatic chamber microcosm experiment was conducted to examine how light affects the hourly sporulation pattern of the beneficial mite pathogenic fungus Neozygites floridana during a 24 h cyclus over a period of eight consecutive days. This was done by inoculating two-spotted spider mites (Tetranychus urticae) with N. floridana and placing them on strawberry plants for death and sporulation. Spore (primary conidia) discharge was observed by using a spore trap. Two light regimes were tested: Plant growth light of 150 μmol m−2 s−1 for 12 h supplied by high pressure sodium lamps (HPS), followed by either; (i) 4 h of 50 μmol m−2 s−1 light with similar HPS lamps followed by 8 h darkness (full HPS light + reduced HPS light + darkness) or (ii) 4 h of 50 μmol m−2 s−1 red light followed by 8 h darkness (full HPS light + red light + darkness). A clear difference in hourly primary conidia discharge pattern between the two different light treatments was seen and a significant interaction effect between light treatment and hour in day during the 24 h cycle was observed. The primary conidia discharge peak for treatment (ii) that included red light was mainly reached within the red light hours (19:00–23:00) and the dark hours (23:00–07:00). The primary conidia discharge peak for treatment (i) with HPS light only was mainly reached within the dark hours (23:00–07:00).
Authors
D. Kristic S. Vujic B. Cupina P. Eric R. Cabilovski M. Manojlovic Peder LombnæsAbstract
In Serbia permanent grasslands represent a significant source of animal feed. However, in most regions the animal production and grazing, and thus the productivity and investment in grasslands, are on a very low level. This research aims to analyse impact of nitrogen fertilization and harrowing on lowland permanent grassland (Vojvodina province, Serbia) in order to improve floristic composition and thus yield and quality. Research was carried out during 2012-2015 in Vojvodina province, Serbia, on permanent grassland which was mainly used for sheep grazing. Trial included two nitrogen rates, namely 40 kg ha-1 and 80 kg ha-1, divided on plots with and without harrowing, as well as control treatments. Floristic composition was mostly composed of species from families Poaceace and Asteraceae with a small number and presence of legume species. The number of species changed in the third and fourth years of the trial. Cynodon dactylon L., Lolium perenne L., Festuca sp., were significantly higher on plots with the higher nitrogen rate, while on the control the most frequent spp. were Trifolium campestre Schreb. and Medicago lupulina L. Harrowing, on the other hand, had smaller impact on improvement of permanent grassland.