The population dynamics of the grape leafhopper (Empoasca vitis) and its egg parasitoids (Mymaridae) were studied at five representative sites in the Franconian wine-growing region from 1998 to 2001. In contrast to other German wine-growing areas, only one generation of grape leafhoppers per season was observed. In general, irrespective of the application of insecticides, the peak density of the first generation was much lower than that of immigrating grape leafhoppers. As the observed mymarid:leafhopper ratios (1:0.8-1:4.8) of the first generation were extremely high, egg parasitoids might be effectively controlling the grape leafhopper in Franconian vineyards. Slightly elevated leafhopper densities at the end of the growing season were caused by migrating sister species. Intervention thresholds were rarely reached; however, stress symptoms as discoloured intercostal leaf areas or rolled leaf edges were widespread. Over the whole study period three mymarid species occurred at all monitoring sites: Anagrus atomus, Stethynium triclavatum and a species, not previously reported in the German wine-growing region, Anagrus avalae. The dominance relationships of these species were site-specific, differing more strongly between than within sites; however, differences could not be related to the kind of management or natural surrounding of the vineyards. A hatching experiment confirmed the biological significance of A. avalae as an effective antagonist.

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Calcium tartrate crystals were observed in the midgut of grape leafhoppers. This unique compound was found for the first time in insects. The size of the crystals varied strongly between and within individuals with a mean length of 153 +/- 87 microm and a mean width of 71 +/- 46 microm. In addition, the number of crystals per individual showed a broad variation and ranged from 1 to 150 crystals/individual. The occurrence of calcium tartrate crystals as well as the number of crystals per individual followed the same seasonal pattern as seasonal vine leaf concentrations of tartaric acid found in a previous study, indicating that calcium tartrate is formed to neutralize the tartaric acid in the gut system. It further implies that the grape leafhopper, rather than being a pure phloem sucker, employs a mixed feeding strategy to satisfy its demands for calcium uptake.

Plant phenology is well known to be affected by meteorology. Observed changes in the occurrence of phenological phases are commonly considered some of the most obvious effects of climate change. However, current climate models lack a representation of vegetation suitable for studying future changes in phenology itself. This study presents a statistical-dynamical modeling approach for Bavaria in southern Germany, using over 13,000 paired samples of phenological and meteorological data for analyses and climate change scenarios provided by a state-of-the-art regional climate model (RCM). Anomalies of several meteorological variables were used as predictors and phenological anomalies of the flowering date of the test plant Forsythia suspensa as predictand. Several cross-validated prediction models using various numbers and differently constructed predictors were developed, compared, and evaluated via bootstrapping. As our approach needs a small set of meteorological observations per phenological station, it allows for reliable parameter estimation and an easy transfer to other regions. The most robust and successful model comprises predictors based on mean temperature, precipitation, wind velocity, and snow depth. Its average coefficient of determination and root mean square error (RMSE) per station are 60% and ± 8.6 days, respectively. However, the prediction error strongly differs among stations. When transferred to other indicator plants, this method achieves a comparable level of predictive accuracy. Its application to two climate change scenarios reveals distinct changes for various plants and regions. The flowering date is simulated to occur between 5 and 25 days earlier at the end of the twenty-first century compared to the phenology of the reference period (1961-1990).

The Asian longhorned beetle Anoplophora glabripennis (ALB) is a dreaded quarantine pest that attacks a wide range of hardwood tree species. However, some of the specified host plants which have to be eradicated in infestation zones such as lime and beech trees almost never get infested or may even be resistant to the ALB. As a result, the specified host plant list needs to be revised based on the data from the infestation areas in the EU, in order to avoid further felling of whole lime avenues and major clear-cutting in parks with old growth. As large differences may exist between species of the same genus, exact species not merely genera should be specified on the host list.