Untersuchungen zur Kältetoleranz und Überwinterung der Deutschen SchabeBlattella germanica (L.) (Blattodea,Blattidae) unter Freilandbedingungen

The extremly biotic and abiotic conditions of a decompositiontip supported the mass population ofB. germanica which enabled the development of a new race by means of evolution factors. In experiments under laboratorical and outdoor conditions the cold-tolerance of this new race was studied. Considering the fact, thatB. germanica can subsist a middle-European winter under outdoor conditions, we may conclude, that the spreading of this animal will not soon come to an end.     

Intraspezifische Differenzierung in der Epidemiologie und Ökologie vonPityogenes chalcographus L. (Col., Scolytidae) unter dem Aspekt der interpopularen Bastardierung

Four regionally different strains and six F₁ interpopular crosses ofPityogenes chalcographus were used for infestation and starvation experiments. In the infestation experiment beetles were placed for three days on vital Norway spruce and the amount of nuptial chambers were recorded. During the viability experiment the insects were kept under a daily varying temperature for 16h at 20°C and for 8h at 10°C. The rel. humidity was set at 93%, 77% and 57%. The infestation potential differs in the susceptibility of host trees and within the populations. Especially the F₁ crosses provide an enhanced attack and potential of injury which are to be considered a case of heterosis. Because of the irregular host-tree preference in some populations it is assumed that there is a highly specific interaction in feeding stimulation. The effect of heterosis is also present in starvation experiments, but it seems to be only restricted to an optimal survival range. It is emphasized that genetic factors play a remarkable role in the interactions between bark beetles and host trees as well as in population dynamics.     

Untersuchungen zum Einfluß von Sonnenlicht auf das Schwärmverhalten von Borkenkäfern

Zusammenfassung Mit Hilfe elektronischer Meßmethoden sowie durch verschiedene weitere Versuchsanordnungen konnte gezeigt werden, daß der Buchdrucker in seinem Anflugverhalten an Pheromonquellen maßgeblich durch die jeweils herrschenden Lichtverhältnisse beeinflußt wird. Es bestand eine deutliche Präferenz von besonnten Standorten. In sonnigen Zeitabschnitten, auch innerhalb von nur wenigen Minuten, waren signifikant höhere Anflugzahlen zu vereichnen als in Phasen mit Bewölkung. Für den Kupferstecher gilt dies nur in eingeschränktem Maße.Diese Zusammenhänge konnten auch anhand von nord-bzw. südexponierten Fallen aufgezeigt werden. Die besonnte Fallenseite fing 4,2mal mehr Buchdrucker als die der Sonne abgewandte Seite. Beim Kupferstecher betrug der Faktor nur 1,66. Die beschriebenen Ergebnisse fanden ihre Bestätigung auch in der Befallssituation im Kalamitätsgebiet. Bei beginnendem Stehendbefall wurden vom Buchdrucker zunächst südexponierte Bestandesränder und hier die zur tageszeitlichen Hauptschwärmzeit besonnten Stämme besetzt.

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Influencing the flight behaviour of bark beetles by light conditions

With the aid of eletronic registration equipment and other experimental methods, it could be shown that the flight behaviour of spruce bark beetles to pheromone sources is strongly influenced by the prevailing light conditions. There is a definite preference for sunny conditions. Even during sunny periods of only a few minutes, significantly more beetles were flying than during overcast periods.A similar pattern of behaviour was observed for P.chalcographus, but there was no statistical evidence. This preference was also seen when pheromone baited traps were set up in a northerly direction with low sunlight levels and a southerly direction with strong sunlight. In the traps facing south 4,2 times more lps typographus were caught than in the north facing traps. P. chalcographus preferred the sunnier traps at a radio of 1,66.These results confirm the fact that at the beginning of an infestation of forest the southerly regions were first to be attacked by spruce bark beetles. Even there trees were first affected where they were exposed to sun during the daily main period of flight activity.

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Mit 2 Abbildungen und 1 Table.     

On biology ofLixus albomarginatus boh. (Col., Curculionidae)

In the coastal regions of the Southern Ukraine adults ofLixus albomarginatus Boh. feed onCakile euxina Pobed. (Brassicaceae). Preimaginal development occurs in the same plants.     

Modified algorithm to determine localized modulus of elasticity of lumber

Summary A procedure has been developed to determine the cut-off frequency in an algorithm to evaluate the localized modulus of elasticity (MOE) in lumber. MOE profiles have been artificially generated to serve as input for evaluation of the procedure. A noise component has also been added to the input record to test the robustness and accuracy of the procedure. Good agreement between program predictions and the known localized MOE values has been obtained. The efficiency of the procedure has also been tested using MOE profiles collected from experiments. The program performed efficiently and program predictions seemed reasonable.     

Changes in the acid structure of wood due to ageing and fossilisation processes

Summary Some fossil woods, differing in botanical species, age, degree of degradation and chemical composition, were analysed with respect to their acid structure. A comparison was carried out with corresponding modern species which, in the case of softwoods, contain carboxylic groups as well as ester groups in almost equal amounts. Moreover the former are subdivided into protonated (20%) and salified forms (80%). The determination of the acid structures in woods was made by means of cation exchange measurements.In all examined fossils the initially protonated form is changed into the salified one because of the leaching carried out by water containing soluble salts. Despite the loss of polyoses, an increase in the content of carboxylic groups was achieved due to hydrolysis of the ester groups. In more degraded samples the amount of carboxylic groups was larger than in the other fossils even if the former possessed only traces of polyoses due to an attack on lignin assessed by acidity of the trifluoroacetic (TFA) derivatives. Proof of these changes and further information on fossils were obtained by I.R. spectroscopy.The authors wish to thank Prof. D. Fengel for the fossils coming from Wackersdorf (Germany)     

Ungewöhnliche Schäden durch Holzwespen (Siricidae,Hym.)

Ohne Zusammenfassung     

Wichtige,in Hokkaido (Japan) durch schädliche Forstinsekten verursachte Probleme

Ohne ZusammenfassungHerr Dr. Motonori Inouye ist der Chef-Forstentomologe der japanischen forstlichen Versuchsanstalt von Hokkaido. Mit dieser Veröffentlichung beginnt eine in zwangloser Folge erscheinende Reibe von Arbeiten, in der über Schädlingsfragen in verschiedenen Ländern berichtet wird. Die Schriftleitung.