Neue Erkenntnisse über Entstehung und Begegnung von Massenvermehrungen an Kiefern‐ und Fichtennadeln fressender Schadinsekten

Abstract

Summary Rearing of Diprion pini larvae in 1960 and 1961 on living twigs in different types of pine wood near Nürnberg showed that mortality of larvae was higher in damp woods than in dry. The coccoon size varied in the opposite way. Measurements with a sugar refractometer showed that the amount of sugar in the needles was higher in dry woods than in damp. The amount of sugar and with it the Diprion increase could be considerably reduced by the use of fertilizers particularly nitrogen.