Zur Nahrungsqualität von Fichtennadeln für forstliche Schadinsekten

As to food quality of spruce needles for forest damaging insects. 2. Comparative analyses of the compounds in spruce needles and the faeces of larvae of Gilpinia hercyniae Htg . Comparative analyses of the compounds in spruce needles and the faeces of larvae of Gilpinia hercyniae Htg. are described as a contribution to systematic model experiments in food quality and development of damaging insects. The technique of isolation is described. As compared with needles the analyses of faeces show a remarkable descrease in the concentrations of glucose, fructose, saccharose and maltose, the last probably being a breakdown product of starch. The decrease in the lipid fraction is accompanied by qualitative changes. The diminuations of proteins are less than those of sugars and lipids, yet consistent. There are strong drifts of concentrations as well as qualitative differences in the fractions of carboxylic and amino acids, indicating a high metabolic turnover rate in needles and larvae respectively. No utilization of cellulose could be demonstrated. On the whole a weak accumulation of pigments, terpene and phenol compounds (e. g. lignin) was found: by passing through the larvae these compounds became more hydrophilic, at the same time their degree of polymerisation increased. Zusammenfassung Als Beitrag zu systematischen Modelluntersuchungen über die Nahrungsqualität von Fichtennadeln für die Entwicklung von Schadinsekten werden am Beispiel von Gilpinia hercyniae Htg. vergleichende Analysen der Inhaltsstoffe von Fichtennadeln und Kot der Larven dargestellt. Die Technik der Isolierung wird beschrieben. Auf Grund des Vergleichs werden die Inhaltsstoffe lösliche Kohlenhydrate, Lipide, Proteine, Amino‐ und Carboxylsäuren, Pigmente, Phenole, Terpene, Lignin, Cellulose in ihrer Eignung als Nährstoffe besprochen.