Development of the nun moth (Lymantria monacha Linnaeus, 1758: Lepidoptera, Lymantriidae) on Douglas fir (Pseudotsuga menziesii), spruce (Picea abies) and pine (Pinus sylvestris) under controlled conditions)

Larvae of the nun moth (Lymantria monacha L.) were bred in parallel experiments on pine (Pinus sylvestris), douglas fir (Pseudotsuga menziesii) and spruce (Picea abies). The larvae were kept under constant conditions in climated rooms or climated chambers on cut branches, which were positioned in tap water. The effect of a temperature range between 16degreesC and 30degreesC and of two different population densities of larvae was examined. The speed of development, the larval mortality, the weight of the larvae and the resulting pupae depending on the tree species were noticed. The development of the larvae with high population density was marginally slower than in populations with low population density, causing slightly lower weights of the pupae in both sexes (Fig. 1, Fig. 4). Spruce is - depending on the examined parameters - the most suitable food source and even caused a faster development (Fig. 1) and higher pupae weights (Fig. 3, Fig. 4) in all temperature experiments. The mortality of the larvae, mainly due to the mortality of young and middle aged larvae, was significantly higher on douglas fir than on spruce or pine (Fig. 2). This result could indicate that the douglas fir is a more unfavourable tree species for the development success of the nun moth than spruce or pine. It is pointed out that results of experiments under controlled conditions can be transfered to field experiments only to a limited extent.