J. Lunderstädt

Phenols from Fagus sylvatica and their role in defence against cryptococcus fagisuga

Abstract In extracts of inner and outer bark of Fagus sylvatica, qualitative dependence of the phenolic composition on infection with Cryptococcus fagisuga feeding in the parenchyma tissue was observed. The seven major compounds were isolated and completely assigned, mainly by two-dimensional NMR techniques. Highest concentrations of (2R,3R)-(+)-glucodistylin, (2S,3S)-(−)-glucodistylin and 3-O-(β- d -xylopyranosyl)taxifolin occur in European beeches strongly infested with beech scale The concentration of cis-coniferin was lowered after attack, while the concentrations of catechin, cis-isoconiferin and cis-syringin remained unaffected. The changes are discussed as a defence reaction.

Induced defence reaction in the phloem of spruce (Picea abies) and larch (Larix decidua) after attack by Ips typographus and Ips cembrae

Abstract The physiological reaction of larch (Larix decidua) and spruce (Picea abies) after attack by Ips cembrae and Ips typographus, respectively, was investigated from 1991 until 1993 by analysis of the constituents of phloem tissue (soluble carbohydrates, protein amino acids, pinitol, shikimic acid, quinic acid, catechin, procyanidines). To exclude behavioural artefacts, the investigation was performed under natural field conditions with free choice of their host by both bark beetle species. A sequence of resistance mechanisms was detected after attack. Dependent upon the intensity, the duration, and the success of the attack at first locally limited changes in the metabolism of attacked trees occurred. These changes resulted in a deterioration in the food quality (shift of the nutrient/inhibiting compounds ratio in favour of the latter) with the effect of disturbing the establishment of the beetles. With stronger and longer lasting attack, long-lasting systemic changes in the metabolism of the whole tree were induced. These resulted, likewise, in a deterioration of the nutrient/inhibiting compounds balance, an increase of the protein biosynthesis and an intensification of the defence metabolism. This reaction was sustained with successful attack until the end of the development of the brood beetles. Thus, the induced resistance reactions were directed against the parent generation and the brood alike, extending from the level of the individual tree to the level of the population of trees.

Physiological defence reactions of young beech trees (Fagus sylvatica) to attack by Phyllaphis fagi

Abstract The physiological reaction to attack by the lachnid Phyllaphis fagi compared with non-infested control plants was examined in whole leaves and leaf phloem of beech ( Fagus sylvatica ) saplings as well as in beach seedlings cultivated in different nutrient substrates. The colonisation density of the lachnids on beech seedlings increased with improved nutrient supply. However, growth was not depressed to a comparable extent. Defence reactions were found at three hierarchic levels. Infested plants exhibited a strongly decreased amino acid/monosaccharide ratio in the entire leaf and leaf phloem. In addition, secondary plant defence substances were detected in beech saplings and lamma shoot leaves of beech seedlings. A systematic reaction, dependent on the infestation density of the lachnid was observed in the leaf phloem of the beech saplings.

Population dynamics of beech scale (Cryptococcus fagisuga) (Coccina, Pseudococcidae) related to physiological defence reactions of attacked beech trees (Fagus sylvatica)

SummaryChanges in the density of beech scale infestation (Cryptococcus fagisuga) of a mature beech stand (Fagus sylvatica) were investigated after gap-cutting in limed and unlimed areas bordering on the gaps and in untreated areas over a 5-year period. Parallelly the concentrations of sucrose, protein amino acids, and procyanidins were examined in the inner and outer bark of non-infested beech trees and beeches infested by beech scale.Irrespective of liming in the areas bordering on the gaps the proportion of beech trees with increasing beech scale infestation was significantly higher, the proportion of beeches with diminishing infestation was significantly lower than in the untreated control areas. Trees with the same infestation tendency occurred in clusters.Physiological defence reactions in the inner and outer bark of the infested beech trees were registrated as an increase in the procyanidin content and a decrease in the protein amino acid content. A change in the outer bark—inner bark—ratio of the infested beech trees showed a transfer of compounds between the inner and outer bark. During the period of observation long-lasting shifts occurred in the pattern of compounds of the bark irrespective of actual infestation intensity.

Zur physiologischen Grundlage der Populationsdynamik der Buchenwollschildlaus, Cryptococcus fagisuga Lind. (Coccidae, Coccina) in Buchen‐ (Fagus sylvatica)beständen

As to the physiological basis of the population dynamics of the beech scale, Cryptococcus fagisuga Lind. (Coccidae, Coccina) in beech‐(Fagus sylvatica)stands

The role of food as a density-determining factor for phytophagous insects with reference to the relationship between Norway spruce (Picea abies Karst) and Gilpinia hercyniae Htg. (Hymenoptera, Diprionidae)

Abstract The role of food as a density-determining factor for phytophagous insects is discussed in terms of the ecophysiological bond (systemic bond) between plant and animal. Data on the larvae of the sawfly, Gilpinia hercyniae , and the spruce needles consumed by the insect under controlled conditions served as the experimental basis. It is shown that the degree of utilizability of the spruce needle protein can be taken as a measure of the strength of the bond between plant and animal. The possibility is discussed of using the systemic bond as an auxiliary means for quantitatively describing the disposition of forest stands.

Impact of external factors on the population dynamics of beech scale (Cryptococcus fagisuga) (Hom., Pseudococcidae) in beech (Fagus sylvatica) stands during the latency stage

Abstract: Within a natural occurrence of beech on weathered lime stone in the hilly region of southern Lower Saxony, the infestation dynamics of Cryptococcus fagisuga as dependent on the flushing status of its host, Fagus sylvatica, were investigated from 1988 to 1995 during the latency stage.

Wirkung von Larvenkot von Dendrolimus pini L. (Lep., Lasiocampidae)nach Frass an Kiefer auf Keimung und Keimlingswachstum von Kiefern-, Birken-und Eichensaat

Abstract: Germination and growth of Pinus sylvestris L., Betula pendula Roth. and Quercus robur L. were investigated under laboratory conditions. Sterilized sand was used as the substrate and supplied with (a) increasing amounts of faeces of larvae of Dendrolimus pini L. which had been reared previously on Scotch pine and (b) a solution of NH4NO3 of the same N‐concentration as the faeces. The germination of pine and birch decreased strongly with increasing amounts of faeces, whereas the germination of oak was unaffected. When the inhibition of germination was overcome the further growth proceeded according to the species‐specific growth pattern during a period of 200 days (oak) and 300 days, respectively (pine, birch). It was influenced neither by the supply of faeces nor of fertilizer. It is concluded from the results that the faeces of phytophagous insects contain inhibitory components which become effective only during the germination process of the species if there is a poor supply of nutrients in the seed (pine, birch). The subsequent stage of germ growth however, is not affected. The results are discussed in terms of a possible ecological function for insects as regulators of the species composition following mass propagations.