Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2005
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
The spruce bark beetle is the most serious pest of mature spruce trees in Eurasia. At low population densities it breeds in weakened or newly dead trees, but at high densities it becomes a tree killer. The exact factors triggering outbreaks are not fully understood, but climatic variables are important candidates. Populations in SE Norway have been monitored since 1979. Various time series methods are used to explore the role of climate in outbreaks of the spruce bark beetle in space and time, and to estimate the distribution of bivoltism under different scenarios of climate change. Large windfall events appear to be a major synchronizer of beetle outbreaks in areas subjected to regionalized weather systems, and the northern border of bivoltism may be moved towards north as a function of increasing temperature. Preliminary models of the population dynamics emphasize the frequency of large windfall events and phenological changes due to temperature increase. Final aims are to estimate the regional risks of forest damage under different scenarios of climate change, and to describe practices that may reduce the impact for forest managers.
Sammendrag
At least three mechanisms are known to cause synchrony among spatially separated insect populations: 1) dispersal among populations, 2) synchronous stochastic effects, often referred to as the Moran effect, and 3) trophic interactions with other species that are either themselves synchronized or mobile.The present study brings in the role of insect taxa for spatial synchrony. The spatial synchrony observed in several North American and Eurasian epidemic bark beetles was compared with patterns of synchrony in outbreaks of defoliating forest Lepidoptera, revealing a marked difference between these two major insect taxa.The bark beetles exhibited a generally lower degree of spatial synchrony than the Lepidoptera, possibly because bark beetles are synchronized by different weather variables that are acting on a smaller scale than those affecting the Lepidoptera, or because inherent differences in their dynamics leads to more cyclic oscillations and hence more synchronous spatial dynamics in the Lepidoptera. Among the epidemic bark beetles tested, spatial synchrony of outbreaks in the Eurasian spruce bark beetle Ips typographus was significantly higher than for the other species.
Sammendrag
Larver i kirsebær antas gjerne å være kirsebærflue uten nærmere undersøkelse. Det er imidlertid funnet viklerlarver i surkirsebær i Vestfold de to siste årene. Artikkelen beskriver hvordan man ser forskjell på larver av fluer og viklere. Bekjempelsen av de to typene skadedyr er forskjellig, så der er viktig å vite hva som er hva.
Sammendrag
I 2004 og 2005 ble det utført en del feltforsøk for å undersøke effekten av to kommersielle preparater av nyttenematoder, Nemasys H og Nemsays L, mot larver av veksthussnutebillen. Resultatene viser at Nemasys H har ingen eller svært dårlig virkning når gjennomsnittstemperaturen i jorda (5-10 cm dybde) faller under 12 grader. For Nemasys L var virkningen ved slik lav temperatur noe bedre, men ikke så god som forventet. Langtidsvirkningen av nematodeutslippetne er ikke undersøkt, men basert på erfaringer fra feltforsøk utført hittil anbefales det å behandle med Nemasys H om høsten eller tidlig på våren når jordtemperaturen er 12 grader eller mer.
Forfattere
Geir Kjølberg Knudsen Marie Bengtsson Trond Hofsvang Gunnhild Jåstad Sverre Kobro Peter WitzgallSammendrag
Det er ikke registrert sammendrag
Forfattere
Richard Meadow Linda Hjeljord Annette Folkedal SchjøllSammendrag
In order to infect target insects after application to soil or plant surfaces, Metarhizium anisopliae conidia must remain viable in the face of abiotic and biotic factors. As a part of an inveestigation to develop M. anisopliae as an agent against the black wine weevil, we investigated the fungus ability to compete with conidia of fungi commonly isolated from soil and aboveground surfaces of strawberry in Norway. In previous work, we determined the speed of germination of the isolates at various temperatures, and investigated the effects of inoculating various nutrient substances with conidia of the insect pathogens, before or together with conidia of Cladosporium sp., Trichoderma spp., Verticillium sp., Botrytis cinerea, and Gliocladium sp. Results showed that the insect pathogens, germinated as quickly as the other fungi only at temperatures >=25C. Although germination spees of the insect pathogens varied between isolates, none germinated nor grew as quickly at 15 or 20C as did the other fungi. When coinoculated with conidia of the environmental isolates on a range of agar media at 20C, growth of the insect pathogens was strongly inhibited. In contrast, when the insect pathogens were inoculated at a distance from the other fungi, their colonies inhibited mycelical growth of all the other fungi; M. anisopliae isolates produced clear antibiosis zones against Cladosporium sp. and B. cinerea. On nutrient-poor media, or when substrate nutrients were depleted, colonies of the insect pathogens were eventually overgrown by Gliocladium sp. and Trichoderma spp.In an experiment where weevil larvae were exposed to conidia of M. anisopliae and T. atroviride either separately or combined, and incubated in sterile soil at 22C, the Metarhizium appeared to be unhibited in killing the larvae and sporulating. Follow-up experiments are plannes to look at this interaction at different temperatures and when applying the fungi to the soil.
Forfattere
Sverre KobroSammendrag
Hann av Aeolothrips manteli er funnet for første gang. Arten kan lett skilles fra de andre norske Aeolothrips artene ved karakterer på antennene og øynene.
Forfattere
May-Guri Saethre Trond HofsvangSammendrag
Timed catches of Cydia pomonella (L.) males in sex pheromone traps were used to investigate the influence of twilight and climatic parameters on the flight activity of the moths at different latitudes. Traps were operated from 15 May until 31 July at several locations between 59ºN and 60ºN in south-eastern Norway, and at Sogndal (61ºN) in western Norway, during 1997-2000. Time and duration of twilights were calculated from May-August for each trap-location, and compared with the activity of C. pomonella. Flight response appeared to be determined by the daily photoperiod, corresponding to time of sunset at the different latitudes involved in the study. This response began about two hours before sunset, and declined around 23:00 and 24:00 hours in the evening, in western and eastern Norway, respectively. Main flight activity in both eastern and western Norway was recorded when temperatures were in the range 10-20 ºC, the relative humidity was above 50 %, and at wind speeds below three m/s at the time of capture. In Norway, light conditions are suitable for C. pomonella flight activity all night long during the entire lifetime of the adult moths. It is concluded that temperature is the limiting factor for flight at high latitudes.
Forfattere
Tor J. Johansen Richard MeadowSammendrag
I 1999-2000 ble pupper av stor og lita kålflue samlet om høsten fra ni lokaliteter i Norge (58-70 ºN). Etter vinterlagring studerte vi klekking i klimarom ved 18 ºC. For lita kålflue var klekketida (50 prosent klekking) 11-12 dager og klekkeperioden (tid mellom 10 og 90 prosent klekking) 2-4 dager. Disse resultatene indikerte bare tidligklekkende og ensartede lokale populasjoner av denne arten. Stor kålflue derimot, hadde svært avvikende biotyper, med tidlige, intermediære og seintklekkende populasjoner. Klekketida varierte mellom fem og ti uker og klekkeperioden mellom to go sju uker. Eventuelle døgngradsmodeller for varsling av stor kålflue må derfor ta utgangspunkt i lokale klekkemønster for denne arten.