@article{RostasEggert2008,
  author    = {Rost{\´a}s, Michael and Eggert, Katharina},
  title     = {Ontogenetic and spatio-temporal patterns of induced volatiles in Glycine max in the light of the optimal defence hypothesis},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-26991},
  year      = {2008},
  abstract  = {Plants attacked by herbivorous insects emit a blend of volatile compounds that serve as important host location cues for parasitoid wasps. Variability in the released blend may exist on the whole-plant and within-plant level and can affect the foraging efficiency of parasitoids. We comprehensively assessed the kinetics of herbivore-induced volatiles in soybean in the context of growth stage, plant organ, leaf age, and direction of signal transport. The observed patterns were used to test the predictions of the optimal defence hypothesis (OD). We found that plants in the vegetative stage emitted 10-fold more volatiles per biomass than reproductive plants and young leaves emitted >2.6 times more volatiles than old leaves. Systemic induction in single leaves was stronger and faster by one day in acropetal than in basipetal direction while no systemic induction was found in pods. Herbivore-damaged leaves had a 200-fold higher release rate than pods. To some extent these findings support the OD: i) indirect defence levels were increased in response to herbivory and ii) young leaves, which are more valuable, emitted more volatiles. However, the fact that reproductive structures emitted no constitutive or very few inducible volatiles is in seeming contrast to the OD predictions. We argue that in case of volatile emission the OD can only partially explain the patterns of defence allocation due to the peculiarity that volatiles act as signals not as toxins or repellents.},
  subject      = {Chemische {\"O}kologie},
  language  = {en}
}
@article{RostasBlassmann2009,
  author    = {Rost{\´a}s, Michael and Blassmann, Katrin},
  title     = {Insects had it first: surfactants as a defence against predators},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-35031},
  year      = {2009},
  abstract  = {Insects have evolved an astonishing array of defences to ward off enemies. Well-known and widespread is the regurgitation of oral secretions (OS), fluids that repel attacking predators. In herbivores, the effectiveness of OS has been ascribed so far to the presence of deterrent secondary metabolites sequestered from the host plant. This notion implies, however, that generalists experience less protection on plants with low amounts of secondary metabolites or with compounds ineffective against potential enemies. Resolving the dilemma, we describe a novel defence mechanism that is independent of deterrents as it relies on the OS' intrinsic detergent properties. The OS of Spodoptera exigua (and other species) was found to be highly amphiphilic and well capable of wetting the hydrophobic cuticle of predatory ants. As a result, affected ants stopped attacking and engaged in extensive cleansing. The presence of surfactants was sufficient to explain the defensive character of herbivore OS. We hypothesize that detergency is a common but unrecognised mode of defence which provides a base level of protection that may or may not be further enhanced by plant-derived deterrents. Our study also proves that insects 'invented' the use of defensive surfactants long before modern agriculture had started applying them as insecticides.},
  subject      = {Pflanzenfressende Insekten},
  language  = {en}
}