Predators and parasitoids are major mortality factors for many herbivorous insects. These members of the third trophic level may increase the fitness of certain plants under herbivore attack. The ecological interaction between the three trophic levels has resulted in some spectacular adaptations in plants as well as in predators and parasitoids. We are particularly interested in the defensive function of chemical signals emitted by plants after herbivore damage. These volatile signals are used by predators and parasitoids to locate their potential prey or host.

Combining analytical chemistry, plant physiology, behavioral ecology and multivariate statistics we attempt to understand how natural enemies of herbivores contribute to the selective pressure that shapes plant defenses.

Plant communication...

...by leaves

Our model plant is maize (Zea mays, L.), its wild relatives and several other cultivated plant species. In warmer climates moths from the genus Spodoptera will attack this crop. We use S. littoralis caterpillars and three species of parasitoids (Cotesia marginiventris and Campoletis sonorensis from the new world and Microplitis rufiventris from the old world) to study various aspects of chemically mediated interactions. We utilize a six-arm olfactometer to combine volatile sampling and the recording of parasitoid behavior.

By using novel chemical analytics and multivariate statistics, we study the relative importance of individual volatile compounds for the attraction of parasitoids. Other projects in our lab concentrate on  the influence of soil microorganisms on induced indirect defense and the search for key compounds by in-situ modification of odor blends, on population genetics of different parasitoid species and foraging behavior of parasitic wasps under natural conditions and on the use of honeydew as a food source for parasitoids.

...or by roots

Recently we expanded our research to a belowground interaction between maize roots and a root feeding beetle species (Diabrotica virgifera virgifera) which was recently introduced into Europe. With the use of a newly developed below-ground olfactometer and found that the entomopathogenic nematode Heterorhabditis megidiswas highly attracted to Diabrotica-damaged maize roots. Additional experiments showed that D.v.virgifera damaged roots produce a sesquiterpene, which we showed to be responsible for the attraction. The identification of these below-ground plant signals could help us to enhance the efficacy of nematodes as biological control agents.

...will be available soon...

...will be available soon...