The predisposition of differently weakened trees of Norway spruce (Picea abies Karst.) to the attack by Gilpinia hercyniae Htg. (Hym., Diprionidae) and Lymantria monacha L. (Lep., Lymantriidae)
1986
Schopf, R. (Goettingen Univ. (Germany, F.R.). Inst. fuer Forstzoologie)
Under laboratory conditions larvae of Gilpinia hercyniae Htg. (Hym., Diprionidae) and Lymantria monacha L. (Lep., Lymantriidae) were reared on branches from visibly healthy or diseased trees of Norway spruce from the Hils mountains (Lower Saxony, BRD). The predisposition of spruce to the attack by these defoliating insects was characterized by the developmental parameters, such as mortality, developmental period, weight gain and egg number. The predisposition of about 100 years old, weakened trees with a reduced but green foliage did not differ from healthy control trees. Diseased young trees (12 years old) with needles turning yellow were less predisposed compared to healthy ones
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