Institut für Pflanzenschutz in Obst- und Weinbau
In fruit growing, diseases caused by phytoplasmas cause great economic damage. There is no direct control option against these cell wall-less bacteria living in the phloem of the plants. They are transmitted by phloem-sucking psyllids of the genus Cacopsylla. Therefore, the current control with synthetic pesticides is directed against these vector insects. However, chemical pesticides have many adverse effects on beneficial insects and the environment. The RNA interference (RNAi) regulates plant development and genome stability, but also plays an important role in defense against hostile organisms. It is triggered by double-stranded RNAs (dsRNAs) that very specifically silence vital genes in the pathogen. In this way, a pesticide can be designed that acts only on very specific organisms, but spares useful insects. In this project, specific dsRNA molecules will be developed and applied that have a detrimental effect on plant-sucking psyllids. For the application a semi-automated stem injection procedure will be developed, as well as the watering with dsRNA containing aqueous solutions to the root zone of fruit trees. For both methods the dsRNA molecules will be specifically formulated for stabilization and optimal uptake by the treated plants. It is known that with these application methods, the dsRNA molecules enter the xylem. Since recent studies on the apple leaf sucker show that this phloem-feeding species also sucks on the xylem of the plant, the sucking behavior of further psyllid species will be recorded and analyzed to identify additional target species for RNAi control. A feeding test will be developed to study the effect of dsRNA on target and non-target organisms in laboratory experiments.
The German Federal Environmental Foundation
