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Climate change may facilitate shifts in the ranges and the spread of insect pests, but a warming climate may also affect herbivorous insects adversely if it disrupts the locally adapted synchrony between the phenology of insects and that of their host plant. The ability of a pest species to colonize new areas depends on its ability to adjust the timing of phenological events in its life cycle, particularly at high latitudes where there is marked seasonality in temperature and day length. Here we incubated eggs of three species of geometrid moth, Epirrita autumnata, Operophtera brumata and Erannis defoliaria from different geographical populations (E. autumnata and O. brumata from Northern Finland, E. autumnata and E. defoliaria from Southern Finland and all three species from Germany) in a climate chamber at a constant temperature to determine the relative importance of geographic origin in the timing of egg hatch measured in terms of cumulative temperature sums (degree days above 5°C, DD5); i.e. the relative importance of local adaptation versus phenotypic plasticity in the timing of egg hatch. In all three species, eggs from northern populations required a significantly lower temperature sum for hatching than eggs from southern populations, but the differences between them in temperature sum requirements varied considerably among species, with the differences being largest for the earliest hatching and northernmost species, E. autumnata, and smallest for the southern, late-hatching E. defoliaria. In addition, the difference in hatch timing between the E. autumnata eggs from Southern Finland and Germany was many times greater than the difference between the two Finnish populations of E. autumnata, despite the fact that the geographical distances between these populations is similar. We discuss how these differences in hatching time may be explained by the differences in hatch-budburst synchrony and its importance for different moth species and populations. We also briefly reflect on the significance of photoperiod, which is not affected by climate change. It is a controller that works parallel or in addition to temperature sum both for egg hatch in moths and bud burst of their host plants.

Background Winter moth (Operophtera brumata) and mottled umber moth (Erannis defoliaria) are forest Lepidoptera species characterized by periodic high abundance in a 7–11 year cycle. During outbreak years they cause severe defoliation in many forest stands in Europe. In order to better understand the spatio-temporal dynamics and elucidate possible influences of weather, stand and site conditions, a generalized additive mixed model was developed. The investigated data base was derived from glue band catch monitoring stands of both species in Central and North Germany. From the glue bands only female moth individuals are counted and a hazard code is calculated. The model can be employed to predict the exceedance of a warning threshold of this hazard code which indicates a potential severe defoliation of oak stands by winter moth and mottled umber in the coming spring. Results The developed model accounts for specific temporal structured effects for three large ecoregions and random effects at stand level. During variable selection the negative model effect of pest control and the positive model effects of mean daily minimum temperature in adult stage and precipitation in early pupal stage were identified. Conclusion The developed model can be used for short-term predictions of potential defoliation risk in Central and North Germany. These predictions are sensitive to weather conditions and the population dynamics. However, a future extension of the data base comprising further outbreak years would allow for deeper investigation of the temporal and regional patterns of the cyclic dynamics and their causal influences on abundance of winter moth and mottled umber.

In den Jahren 1996 und 1997 wurde in ausgewahlten Gebieten des Rheinlands die Populationsdichte von Schmetterlingsraupen erfast, die an Eichen (Quercas robur undQ. petraea) und an Hainbuchen (Carpinus betulus) Kahlfras, an Rotbuchen (Fagus sylvatica) erheblichen Frasschaden verursachten. An dem Blattfras waren insgesamt 63 Schmetterlingsraupen beteiligt. An Eichen erfolgte Kahlfras gleichzeitig durch mehrere Arten (Operophtera brumala, O. fagata, Erannis defoliaria undTortrix viridana), wahrend an Hainbuche und RotbucheOperophtera fagata fur den hohen Frasschaden verantwortlich war. Standorte, an denen Massenvermehrungen nachgewiesen wurden, waren gut mit Nahrstoffen versorgt und bestatigen so die Hypothese zur Ressourcenverfugbarkeit. Die Populationsdichten der Schmetterlingsraupen waren an Eichen so gros, das es zu inter- und intraspezifischer Konkurrenz (scramble competition) kam. In Eichenbestanden, die mit Rotbuchen unterbaut waren, wurde die Konkurrenzsituation unter den Schmetterlingsraupen vermindert. Somit konnen waldbauliche Masnahmen, besonders bei einer Massenvermehrung vonOperophtera fagata, zu einer Verlangerung der Gradation beitragen.

Erannis tiliaria Harr. and Erannis defoliaria Cl. are closely related species (Rindge 1975) that have similar external appearance and flight period. Erannis tiliaria occurs in North America, whereas E. defoliaria is confined to Europe. Erannis defoliaria occasionally damages oak, Quercus spp. L. (Fagaceae), and cheny, Prunus spp. L. (Rosaceae) (Reichart 1993). During its 1975 outbreak, E. tiliaria severely defoliated 200 000 ha of white and yellow birch, Betula alleghaniensis Britt. and Betula papyrifera Marsh. (Betulaceae), respectively (Howse et al. 1995).

Both the enantiomers of (3Z,9Z-cis-6,7-epoxy-3,9-nonadecadiene,a pheromone component of Erannis defoliaria, were synthesized using the Sharpless asymmetric epoxidation as the key step

The melanic forms of the two geometrid moths Erannis defoliaria and Agriopis marginaria are controlled by autosomal loci with melanic dominant over non-melanic forms. In E. defoliaria segregation ratios conform to expectation but in some families of A. marginaria excesses of melanic females may be due to misclassification in that sex or to differences in viability between melanic and non-melanic genotypes.