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.

1997

Abstract

Twenty-five year old Norway spruce trees (Picea abies) were inoculated with four blue-stain fungi. Each tree was inoculated three times with each fungus and three times with sterile agar as a control, giving a total of 15 inoculations per tree. There was little variation in the extent of phloem necrosis produced in response to the different fungi, but five weeks after inoculation necrosis induced by Ceratocystis polonica and Ambrosiella sp. were significantly longer than those for the other fungi. At the same time, C. polonica had induced sapwood desicc-ation twice as deeply into the wood as any other fungus.Hyphal growth of the fungi into phloem and sapwood followed the same pattern as necrosis length and desiccation depth. Five weeks after inoculation C. polonica had penetrated phloem and sapwood further than any other fungus. It grew slower than the other fungi in both tissues the first week after inoculation, but the four following weeks it grew faster than all other fungi.

Abstract

Developmental time and survival of eggs, larvae, pupae and adult females of the cabbage moth, Mamestra brassicae (L.) (Lepidoptera: Noctuidae) were investigated at different temperatures within the range of 5 to 23oC. In addition, the influence of temperature during the larval period on the weight of the succeeding pupae was studied, as well as the effect of temperature on fecundity of adult females. The lower developmental thresholds (Tb) and thermal requirement (DD) were established for all developmental stages and the larval instars using linear regression analysis. Tb and DD were 8.6°C and 75 degree-days for eggs, 5.4°C and 496 degree-days for the total larval period, 7.2°C and 304 degree-days for pupae, and 5.0°C and 56 degree-days for adult females, respectively. Pupal mortality was low at all temperatures. The survival of eggs and larvae was highest at 18oC, whereas mortality was 100% at 8.5oC. Larval mortality was highest in the first instar and decreased with increasing age. Pupae gained the highest weight when the larvae were reared at 18oC, and decreased with declining temperature. Temperature had no significant effect on total fecundity or fertility. Fecundity was basically unimodal distributed at all temperatures. At low temperatures the egg deposition period was markedly prolonged.