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
Myrmica specioides Bondroit, 1918 and Formica cunicularia Latreille, 1798 are recorded in Norway for the first time. Both species were found in 2008 at Jeløya, Østfold County in South-Eastern Norway. A total of 54 outdoor-living ant species are now known to occur in Norway.
Abstract
The common European cerambycid Leiopus nebulosus (Linnaeus, 1758) is herein split into two sibling species. The male genitalia characters, as well as spermathecae in females, were examined and found to provide strong support for this separation. A new species, Leiopus linnei sp. nov., is based on specimens mainly from Scandinavia. The establishment of the new species is supported by DNA barcoding of Scandinavian specimens of L. nebulosus, L. linnei sp. nov., and L. punctulatus (Paykull, 1800). There are significant genetic differences between all these species. The geographical distribution and the bionomy of L. nebulosus and L. linnei sp. nov. are described. The type of Cerambyx nebulosus Linnaeus, 1758 is lost. A neotype of Cerambyx nebulosus, currently Leiopus nebulosus (Linnaeus, 1758), is designated and a redescription of L. nebulosus is presented. A key for the identification of L. nebulosus and L. linnei sp. nov. is provided. The varieties L. nebulosus var. dissimilis Pic, 1889, L. nebulosus var. unifasciatus Pic, 1891, and L. nebulosus var. siculus Pic, 1924 are considered as junior synonyms, syn.nov. of L. nebulosus.
Abstract
Control of dock species are a true bottleneck in the development of grassland based organic forage production in Norway. Rumex obtusifolius, Rumex crispus and Rumex longifolius are among the most important perennial weeds in grassland areas throughout the world. These dock- species are undesired in grasslands because they decrease yields and reduce forage feeding value. The experiment in our study is carried out as a full-factorial design, including key-factors, which may influence dock behaviour significantly. The first factor, (i) date of grassland establishment, may be important for preventing /decreasing the flush of seedlings from seeds as well as shoots from root fragments. The purpose of the second factor, (ii) black fallow, is both false seedbed preparation and decreasing food reserves in underground plant parts. The third factor, (iii) is the use of equipment for cutting the taproot either (a) before ploughing by using a tractor propelled rotovator, or (b) cutting the dock taproot in the same operation as ploughing by using a prototype ¿two layer dockplough¿. The biological background for cutting the taproot before ploughing is that many studies have shown that new shoots only come from the 5 upper cm of the taproot. Furthermore, our hypothesis is that shoots from highly fragmented regenerative parts (the neck) of the taproot placed deep will not reach the soil surface before their reserves are depleted. Experiments were carried out at 3 and 4 locations in 2007 and 2008, respectively. Weed development were assessed as number of emerging seedlings as well as number of sprouting plants from root fragments, both in the year when the treatments were carried out and the following year. The results are yet not completely analyzed, but preliminary results indicate that plants from seeds frequently are more numerous than plants from roots. At least at some locations and years both the use of rotovator and the ¿dock plough¿, has reduced the number of plants from root fragments with approx. 50%. However, our experiments have shown that ¿dock plough¿ prototype has to be improved, especially because it did not cut the taproot near the open furrow, and did not bury the green parts well enough.
Abstract
No abstract has been registered
Authors
Nina JohansenAbstract
Continuous light is a promising method to reduce the problems with rose powderymildew in greenhouse rose production. The effects of such a light regime on the performance of insect pests on roses have so far not been investigated. In the present study, survival, developmental time, and reproduction during one generation of the greenhouse whitefly, Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae), were characterized on roses, Rosa x hybrida cv. Passion, grown in climate chambers with long-day conditions (L20:D4) or continuous light (L24:D0) at 21 oC and fluctuating relative humidity (mean 74%, range 47–96%). Whiteflies reared under continuous light had lower immature survival and fecundity and shorter female longevity than whiteflies reared under long-day conditions, but immature developmental time was only slightly affected. Life-table analysis showed that the net reproductive rate (Ro) and intrinsic rate of natural increase (rm) were reduced by 85 and 76%, respectively, and the time for the population to double its size (D) was 4.2 times longer under continuous light. Thismean that the whitefly population growth under continuous light was strongly reduced compared with the traditional light regime used in rose production.
Abstract
No abstract has been registered
Abstract
In this study we aimed at understanding the mechanisms that affects an epidemic development of Neozygites floridana in a Tetranychus urticae population. This was done by comparing how many spores a cadaver infected with a N. floridana isolate could produce and at what distance and in which directions they could be thrown on a coverslip at temperatures relevant to the northern hemisphere (13, 18 and 23oC). The highest number of spores were produced at 13oC at a number of 1886. Numbers of spores thrown at 18oC and 23oC were 1733 and 1302 respectively. Temperature had a significant effect on sporulation. Most of the spores were thrown at a distance of 0-0.6 mm from the cadaver. Cadavers placed on the underside of a coverslip were able to throw spores back up on the coverslip surface. A whole plant bioassay was also conducted to reveal where on a plant T. urticae infected with N. floridana die and sporulate. Cadavers showed a different verical distribution on the cucumber plant compared to healthy spider mites. Most of the cadavers were located at the lower to the middle part of the plant, while healthy spider mites were more evenly distributed on the whole plant.
Abstract
Neozygites floridana is a fungus in the order Entomophthorales that is a natural enemy of several spider mite species including the two-spotted spider mite, Tetranychus urticae. When conditions are right, this fungus may cause epizootics in spider mite populations and kill high numbers of mites. The fungus is therefore promising for biological control of T. urticae in strawberry and can be used in combination with other pest management strategies. Our previous studies have shown that N. floridana is compatible with other biocontrol methods such as predatory mites. Phytoseiulus longipes fed on fungus-infected T. urticae laid equal number of eggs to those fed on healthy prey. This indicates that the fungus does not affect this predatory mite negatively. In a choice experiment (hosts with and without N. floridana), P. longipes fed indiscriminately irrespective of the presence of the fungus. The compatibility of biological control methods with pesticides is of great importance for an integrated pest management system to work well. Some acaricides and fungicides have the potential to affect both beneficial fungi and predatory mites and careful selection of pesticides that are not harmful to these beneficial organisms can promote their biocontrol potential. Our studies have shown that the fungicides captan, mancozeb, tolylfluanid, fenhexamid, cyprodinil + fludioxonil affect N. floridana in a way that may be detrimental to the biocontrol potential of this beneficial fungus in the field. Use of resistant varieties is also important in integrated pest management because pests are known to be more vulnerable to pathogens if they feed on poor or resistant plants and our studies on effects of host plants of spider mites confirms this.
Abstract
No abstract has been registered
Academic – Threshold facilitations of interacting species
Bjørn Økland, Olav Skarpaas, Kyrre Kausrud
Abstract
No abstract has been registered