TY  - JOUR
AB  - Plants are hosts for above- and belowground insect communities that can influence each other via above-belowground plant-physiological dynamics. To mediate interactions, plants produce secondary metabolites, including terpenoids, and mixtures can differ intraspecifically. While intraspecific variation in plant chemistry gained increased interest, the extent to which intraspecific differences in plant chemistry mediate above-belowground interactions of herbivores remains unclear. We used a full factorial design with six distinct terpenoid chemotypes, differing in their chemical diversity of tansy (Tanacetum vulgare). We exposed these to the aboveground herbivore Macrosiphoniella tanacetaria (Hemiptera: Aphididae), the belowground herbivore Agriotes sp. (Coleoptera: Elateridae), no herbivore or both herbivores, to determine if chemotypes or the chemical diversity of plant compounds affected aphid performance and if the interactions between herbivores were mediated by the chemical profile. We found that aphid colony size differed between chemotypes, with the strongest colony increase over time in a mixed chemotype, and the weakest in a β-thujone chemotype. Root herbivory had no effect on aphid colony size, regardless of the chemotype. Aphid colony size was positively correlated with terpenoid evenness, but not with terpenoid Shannon diversity, terpenoid richness, or relative terpenoid concentration. Tansy chemotypes differed in their morphological responses (final plant height and final plant dry weight) and average leaf chlorophyll content to aboveground herbivory, whereas belowground herbivory exerted minimal impacts. Overall, our results show that intraspecific variation in terpenoid profiles directly modify ecological interactions on a plant, with plant chemistry mediating aphid performance and chemotypes differing in their morphological responses to herbivory.
AU  - Neuhaus-Harr, A.*
AU  - Ojeda-Prieto, L.*
AU  - Zhang, X.*
AU  - Schnitzler, J.-P.
AU  - Weisser, W.W.*
AU  - Heinen, R.*
C1  - 74842
C2  - 57632
CY  - Van Godewijckstraat 30, 3311 Gz Dordrecht, Netherlands
TI  - Aphid colony size in Tansy is affected by plant chemical composition but not by belowground herbivory.
JO  - J. Chem. Ecol.
VL  - 51
IS  - 3
PB  - Springer
PY  - 2025
SN  - 0098-0331
ER  - 

TY  - JOUR
AB  - Many environmental and interactive important traits of bacteria, such as antibiotic, siderophore or exoenzyme (like cellulose, pectinase) production, virulence factors of pathogens, as well as symbiotic interactions, are regulated in a population density-dependent manner by using small signaling molecules. This phenomenon, called quorum sensing (QS), is widespread among bacteria. Many different bacterial species are communicating or "speaking" through diffusible small molecules. The production often is sophisticatedly regulated via an autoinducing mechanism. A good example is the production of N-acyl homoserine lactones (AHL), which occur in many variations of molecular structure in a wide variety of Gram-negative bacteria. In Gram-positive bacteria, other compounds, such as peptides, regulate cellular activity and behavior by sensing the cell density. The degradation of the signaling molecule-called quorum quenching-is probably another important integral part in the complex quorum sensing circuit. Most interestingly, bacterial quorum sensing molecules also are recognized by eukaryotes that are colonized by QS-active bacteria. In this case, the cross-kingdom interaction can lead to specific adjustment and physiological adaptations in the colonized eukaryote. The responses are manifold, such as modifications of the defense system, modulation of the immune response, or changes in the hormonal status and growth responses. Thus, the interaction with the quorum sensing signaling molecules of bacteria can profoundly change the physiology of higher organisms too. Higher organisms are obligatorily associated with microbial communities, and these truly multi-organismic consortia, which are also called holobionts, can actually be steered via multiple interlinked signaling substances that originate not only from the host but also from the associated bacteria.
AU  - Hartmann, A.
AU  - Schikora, A.*
C1  - 8196
C2  - 30014
SP  - 704-713
TI  - Quorum sensing of bacteria and trans-kingdom interactions of N-Acyl homoserine lactones with eukaryotes.
JO  - J. Chem. Ecol.
VL  - 38
IS  - 6
PB  - Springer
PY  - 2012
SN  - 0098-0331
ER  - 

TY  - JOUR
AU  - Bonello, P.*
AU  - Storer, A.J.*
AU  - Gordon, T.R.*
AU  - Wood, D.L.*
AU  - Heller, W.
C1  - 10102
C2  - 21128
SP  - 1167-1182
TI  - Systemic effects of Heterobasidion annosum on ferulic acid glucoside and lignin of presymptomatic ponderosa pine phloem and potential effects on bark-beetle-associated fungi. 
JO  - J. Chem. Ecol.
VL  - 29
PY  - 2003
SN  - 0098-0331
ER  -