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Zur Kenntnis der Fichten-Blattwespen. III. Die Apparenzen der Diprionini

Walter Thalenhorst
Zeitschrift für Pflanzenkrankheiten (Pflanzenpathologie) und Pflanzenschutz
Vol. 62, No. 6 (Juni 1955), pp. 353-361
Published by: Verlag Eugen Ulmer KG
Stable URL: http://www.jstor.org/stable/43231035
Page Count: 9
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Zur Kenntnis der Fichten-Blattwespen. III. Die Apparenzen der Diprionini
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Abstract

In South Lower Saxony, Gilpinia abieticola (D.T.), hercyniae (Htg.) and polytoma (Htg.) appear, normally, in two seasonal generations. First generation larvae (from end of May until beginning of July) complete their development without diapause and produce, as adults, the second generation (larvae from August to October) which overwinters. Mid-summer larvae (July) seem to show a strongly marked tendency to prolonged diapause; they emerged from their cocoons posterior to the adults of the second generation although having grown up prior to them. This indicates the existence of a univoltine cycle interfering with the normal bivoltine one ; both cycles, however, seem not to be fixed. Variabilities in speed of larval development and in tendency to diapause confuse, especially in the later larval stages, the inter-generation limits. Interspecific differences in these variabilities are, if existing, not reflected in the phenological data and have to be traced out in further investigations.

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