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.
2009
Abstract
The vine weevil, Othiorynchus sulcatus, is a serious pest in strawberries and biological control methods are needed to combat this pest. Formulations of the insect pathogenic fungus Metarhizium anisopliae is registered for use against Otiorhynchus spp. in several countries but no fungal control agents are avilable for control of O. sulcatus in Norway. All developmental stages of Otiorhynchus spp. are susceptible to virulent insect pathogenic fungal species, but best control has been achieved against the larvae (Moorhouse et al. 1992). A number of studies have shown that M. anisopliae and Beauveria bassiana have good potential against Otiorhynchus spp. (Cross et al. 2001). In field grown strawberries, good control with Metarhizium has been reported when environmental conditions for the fungus are favourable (Oakley 1994). Temperatures in excess of 15oC are required for good control by most fungal isolates. Low temperature is therefore a major restricting factor for use of fungi outdoors (Gillespie et al. 1989, Soares et al. 1983). Isolates with low temperature optimums could therefore be well suited for field conditions in Northern Europe, where soil temperatures at the time when most larvae are found in the soil in autumn are 10-12oC. Norwegian M. anisopliae and B. bassiana isolates have shown promising results against O. sulcatus larvae at low temperatures in laboratory bioassays (Hjeljord & Klingen 2005). One of the Norwegian M. anisopliae isolates has also shown good competition with other soil fungi in laboratory experiments (Hjeljord & Meadow 2005). In addition to being cold tolerant, rhizosphere competence is important for fungal control agents that are used to control root feeding pests. "Rhizosphere competence" has been defined when considering biological control agents as "the ability of a microorganism, applied by seed treatment, to colonize the rhizosphere of developing roots" (Baker 1991). In this study we therefore aimed at testing the survival and rhizosphere competence of two different cold active Norwegian isolates (M. anisopliae isolate NCRI 250/02 and B. bassiana NCRI 12/96) in a semi field experiment in Norway. These were compared with the commercially avilable M. anisopliae isolate Ma43 originating from Austria (the isolate is also known to have many other names (Eilenberg 2008)). The study was conducted by estimating fungal concentrations in the bulk and rhizosphere soil surrounding the strawberry plant roots by counting colony forming unists (CFUs). The highest numbers of B. bassiana NCRI 12/96 CFUs were seen in the rhizosphere at 1.87x109 per liter soil 3 months after application. The highest numbers of M. anisopliae NCRI 250/02 CFUs were seen in the rhizosphere at 2.41x109 per liter soil 1 year after application. Numbers of CFUs for the M. ansiopliae Ma43 CFUs were generally lower than for the Norwegian isolates, but also for this isolate a higher fungal concentration was found in the rihzosphere soil than in the bulk soil.
Authors
Maria Björkman B. Båth P. Hambäck B. Rämert K. Thorup-KristensenAbstract
Intercropping has been shown to lead to reduced attacks from several pest insects, as for example the turnip root fly (Delia floralis). This study shows that the oviposition of D. floralis can be reduced further if intercropping is combined with a trap crop. Yield losses due to plant competition in the intercropping can be reduced by pruning the roots of the companion plant and by choosing a low competitive companion plant species.
Authors
Eva Birken Mekjell MelandAbstract
This paper describes briefly the phenomena of alternate bearing of European plums and point out that more detailed investigations about physiological factors, in particular plant hormones, involved in the flowering process are of great importance.
Abstract
No abstract has been registered
Authors
Ole Martin Eklo Marit Almvik Randi Bolli Trond Børresen Terje Haraldsen Lars Egil Haugen Roger Holten Gunnhild RiiseAbstract
No abstract has been registered
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No abstract has been registered
Authors
Jorunn Elisabeth Olsen Anna Holefors Lars Morten Opseth Daniel Asante Olavi Junttila Jørgen Aleksander Mølmann Igor A. Yakovlev Carl Fossdal Øystein JohnsenAbstract
No abstract has been registered
Authors
Bolette Bele Hanne Sickel Tor Lunnan Ann Norderhaug Marianne Østerlie Roger K. Abrahamsen Liv Sigrid Nilsen Mikael OhlsonAbstract
No abstract has been registered
Authors
Karl ThunesAbstract
No abstract has been registered
Abstract
Introduction: Current risk assessment procedures for contaminated land and for pesticides often fail to properly characterize the risk of chemicals for environment or human health and provide only a rough estimate of the potential risk of chemicals. Chemicals often occur in mixtures in the environment, while regulatory agencies often use a chemical-by-chemical approach, focusing on a single media, a single source, and a single toxic endpoint. Current concepts to estimate biological effects of chemical mixtures mainly rely on data available for single chemicals, disregarding interaction between chemicals in soils. The importance of soil microbes and their activity in the functioning of soils impose a need to include microorganisms in soil quality assessments (Winding et al., 2005) including terrestrial ecotoxicological studies. Numerous papers have been published on the effects of different contaminants on soil microbes, establishing changes in soil microbial diversity as an indicator of soil pollution, but only a limited number of molecular studies investigating fungal diversity in the environment have been performed. The main objective of the study presented here, is to assess the applicability of changes in soil microbial diversity and activity levels as indicators of ecologically relevant effects of chemicals contamination. We have studied the effects of the fungicide picoxystrobin and the chemical 4-n-nonylphenol, on the microbial biodiversity in a Norwegian sandy loam with focus both on prokaryotes and the fungal species. 4-n-nonylphenol is a chemical occurring in high amounts in sewage sludge, hence, these chemicals may occur as single chemicals as well as in mixtures in soils. This work is part of the research project ‘Bioavailability and biological effects of chemicals - Novel tools in risk assessment of mixtures in agricultural and contaminated soils" funded by the Norwegian research council.Methods: Soil samples were treated with the single chemicals or mixtures and incubated at 20°C. Continuous monitoring of respiration activity as well as occasional destructive sampling for extraction of soil DNA, RNA, and chemical residues was performed through a 70 d period. Amplification of soil bacterial and fungal DNA was followed by T-RFLP analysis to assess chemicals effects on soil microbial diversity. Further work will include analyses of extracted soil RNA to assess chemicals effects on important soil functions (e.g. nitrogen cycling, decomposition of organic matter) and an assessment of chemicals effects on the genetic diversity of the soil by high throughput shot-gun sequencing. Finally the results will be evaluated to assess the suitability of any specific group, species or activity/function as biomarker for the selected chemicals (and possibly their group of chemicals).Results and conclusions: A project outline and preliminary results from the project will be presented at the conference.ReferencesWinding A, Hund-Rinke K, Rutgers M (2005). The use of microorganisms in ecological soil classification and assessment concepts. Ecotoxicology and Environmental Safety 62: 230-248.