I am interested in the effects of below ground mutualisms on plant-herbivore interactions. One of such mutualistic relationships is the association of mycorrhizal fungi with plants. Especially vesicular arbuscular mycorrhizal fungi (VAM) live in symbiosis with the vast majority of wild and crop plants. The plant provides the fungi with carbohydrates while the fungi enhance the uptake of phosphorus, water and other micro-nutrients. This in turn leads to changes in -for example - plant biomass, C/N-ratio or the presence and composition of secondary plant metabolites and thus alters plant quality. Therefore it can be assumed that mycorrhizal fungi also will affect herbivore performance. Some previous studies investigated this relationship but produced conflicting results. However there seem to be some general trends: Chewing insects and especially generalist herbivores appear to be negatively affected by VAM while sucking insects and specialist herbivores seem to benefit from the fungal association.

In my diploma thesis I will try to “draw a bigger picture” about the effect of VAM on plant-herbivore interaction and therefore address the following questions:

(i) Do a sucking and a chewing herbivore generally respond differently to VAM colonisation across a range of plant species? Further, the performance of herbivores on VAM plants may be influenced by the ability of the plant to allocate the additional resources (due to the fungal association and thus higher rates of photosynthesis) to defense mechanisms. However, plants vary in their ability to show induced defence. Such defenses are more common in herbs than in grasses. Therefore I am going to test if (ii) mycorrhiza affect herbivores differently when grown on herbs showing induced defense than on grasses.

Microcosm experiment: “Effects of plant genotype on tri-trophic interactions”

A second mutualistic relationship is the close association of legumes with rhizobia - soil bacteria that fix nitrogen after becoming established inside root nodules of leguminous plants. Here almost no investigations about the effect of rhizobia on herbivores do exist. In green-house experiments I investigate the effects of rhizobia on plant-herbivore interactions using White clover ( Trifolium repens ). Further, the effects of the ability to produce secondary compounds on this interaction will be evaluated using cyanogenic and acyanogenic strains of T. repens .

Faeces of the patagonien hare (spanish word: mara)
and the european hare (spanish word: liebre)
with typical plants of their diet.

During my studies I completed a project at the working group of Prof. Dr. Ricardo Ojeda, Argentinian Institute for Aridlands research (CONICET), on the investigation of potential competition between the european hare ( Lepus europaeus ) and the patagonian hare ( Dolichotis patagonum ) in the UNESCO Man and the Biosphere Reservat Nacunan ( Mendoza , Argentina ). Finally, I am interested in student administration and since a couple of years I have been serving as a member of various student boards.

Talks & Posters

Kempel, A., Brandl, R. & M. Schädler (2006) Effects of plant genotype on tri-trophic interactions – Poster, 36 th annual meeting of the Ecological Ecological Societiy of Germany, Austria and Switzerland (GfÖ) in Bremen (Germany), 11-15 September 2006.