Beneficial anthropods in the canopy E9
|In a six year investigation, the effects of
organic and conventional cultivation methods on general plant performance were studied on
a total area of 6 ha on the Rhine island Mariannenaue/Rheingau, Germany. The conversion in
cultivation methods proceeded on a 4 ha was starting in 1987. Investigated varieties were
the wine-grapes Riesiing and Kerner. The aim of the study was to find and describe the
differences induced by various cropping systems, using quantitative measures, to assess
the varietal productive potential, both vegetatively and reproductvely. Predator mite
Thyplodromus pyri were introduced via old wood into the most severely infested cultivation
system, in spring 1988 and developed a stable population due to favorable climatic
conditions and abundant prey.
The number of predaceous mites was on the average 4-6 individuals/leaf throughout the vegetation period, which prevented any increase in spider mite population. In every year on the end of the vegetation period a higher population of red spider mites developed without any damages. The natural decrease in predaceous mite population (migration into winter hidings, slower reproduction rate) caused an increase in red spider mite populations. Besides the predatory mite population, a number of other beneficial arthropodes was also quantitatively and qualitatively assessed between 1987 to 1992. Not only spider mites were controlled by predators but also some caterpillars, vine mites, gall mites and grape leafhoppers.
In the organic cultivation system a significant influence of the blossoming cover crop, which served as a food source and attractant was observed. A significant difference of the spider fauna in the levels of the grape vine foliage was discovered between the different cultivation systems. On the organic farming system the most genia, species and individuals were found.
Engel, R. (1991): Die Raubmilbe Typhlodromus pyri - mehr als nur ein Spinnmilben-vertilger. Dt. Weinbau-Jahrbuch, 4 (2), 217-224.
Hill, G. K. & Schlamp, H. A. (1987): Die Bedeutung der Raubwanzen Orius minutus (Heteroptera, Anthocoridae) in der acarophagen Räubergemeinschaft der Reben in Rheinhessen. Wein-Wissenschaft, 42, 400-420.
Hofmann, U. (1991): Untersuchungen über die Umstellungsphase auf ökologische Bewirtschaftungssysteme im Weinbau im Vergleich zur konventionellen Wirtschaftsweise am Beispiel Mariannenaue/Erbach. Geisenheimer Berichte 8, Diss. Uni - Giessen.