Costs and benefits of phytochemical diversity in coevolved systems

Chemical Ecology of Plant-herbivore Interactions

Plants produce a puzzling diversity of defensive chemicals in their struggle to deter herbivorous enemies. Complex chemical mixtures may present defensive advantages over single compounds, for example via multi-target toxicity or compound-compound facilitation. Chemical diversification is therefore considered a strategy to escape coevolved herbivores. At the same time, such diversification must be costly to the plant, in terms of both raw building blocks and maintenance costs for increasingly complex synthesizing machinery.

We aim to elucidate the selective forces that drive chemical diversification. We use a newly established model plant system and employ a combination of experimental ecology and different techniques including metabolomics, transcriptomics, and phylogenetic comparisons. In a two-pronged approach, we focus on the defensive benefits of diverse chemical mixtures via altered feeding behavior and success of generalist and specialist herbivores, as well as on the cost of diversification in terms of negative impact on plant growth and reproduction. Ultimately, we will thus be able to link variation in genes and metabolites to success in a variable and changing environment.

Recent Publications

  • Toxicity of Milkweed Leaves and Latex: Chromatographic Quantification Versus Biological Activity of Cardenolides in 16 Asclepias Species
    Zuest, Tobias; Petschenka, Georg; Hastings, Amy P.; Agrawal, Anurag A.
    JOURNAL OF CHEMICAL ECOLOGY, 45 (1):50-60; 10.1007/s10886-018-1040-3 JAN 2019
  • Convergent evolution of a metabolic switch between aphid and caterpillar resistance in cereals
    Li, B; Forster, C; Robert, CAM; Zust, T; Hu, L; Machado, RAR; Berset, JD; Handrick, V; Knauer, T; Hensel, G; Chen, W; Kumlehn, J; Yang, P; Keller, B; Gershenzon, J; Jander, G; Kollner, TG; Erb, M
    SCIENCE ADVANCES, 4 (12):10.1126/sciadv.aat6797 DEC 2018
  • Erysimum cheiranthoides, an ecological research system with potential as a genetic and genomic model for studying cardiac glycoside biosynthesis
    Zust, T; Mirzaei, M; Jander, G
    PHYTOCHEMISTRY REVIEWS 17(6): 1239-1251, DOI: 10.1007/s11101-018-9562-4, DEC 2018
  • Climate Change and Insect Pests: Resistance Is Not Futile?
    SN Johnson, T Züst
    Trends in plant science 23 (5), 367-369, 2018
  • What doesn't kill you makes you stronger: the burdens and benefits of toxin sequestration in a milkweed aphid
    T Züst, S Mou, AA Agrawal
    Functional Ecology 10.1111/1365-2435.1314 2018
  • Erysimum cheiranthoides, an ecological research system with potential as a genetic and genomic model for studying cardiac glycoside biosynthesis
    T Züst, M Mirzaei, G Jander
    Phytochemistry reviews, 1-13, 2018
  • Population transcriptomic characterization of the genetic and expression variation of a candidate progenitor of Miscanthus energy crops 
    Juan Yan, Zhihong Song, Qin Xu, Lifang Kang, Caiyun Zhu, Shilai Xing, Wei Liu, Josef Greimler, Tobias Züst, Jianqiang Li, Tao Sang
    MOLECULAR ECOLOGY, 26 (21): 5911-5922; NOV 2017
  • Trade-offs between plant growth and defense against insect herbivory: an emerging mechanistic synthesis
    T Züst, AA Agrawal
    Annual Review of Plant Biology 68, 513-534, 2017
  • Plant chemical defense indirectly mediates aphid performance via interactions with tending ants 
    Zuest, Tobias; Agrawal, Anurag A. 
    ECOLOGY, 98 (3): 601-607; MAR 2017
  • Population growth and sequestration of plant toxins along a gradient of specialization in four aphid species on the common milkweed Asclepias syriaca 
    Zuest, Tobias; Agrawal, Anurag A. 
    FUNCTIONAL ECOLOGY 30 (4): 547-556 APR 2016 Article (Details)
  • Evolution of Plant Growth and Defense in a Continental Introduction 
    Agrawal, Anurag A.; Hastings, Amy P.; Bradburd, Gideon S.; et al. 
    AMERICAN NATURALIST 186 (1): E1-E15 Published: JUL 2015 Article (Details)
  • Above-ground herbivory by red milkweed beetles facilitates above- and below-ground conspecific insects and reduces fruit production in common milkweed 
    Erwin, Alexis C.; Zuest, Tobias; Ali, Jared G.; et al. 
    JOURNAL OF ECOLOGY 102 (4): 1038-1047 JUL 2014 Article (Details)
Zuest Tobias

Dr. Tobias Züst
University of Bern
Institute of Plant Sciences
3013 Bern

Tel: +41 (0)31 631 49 38

Research topics

  • Evolution of cardiac glycosides in Erysimum spp.
  • Molecular mechanisms of phytochemical diversification
  • Inducible defenses and growth costs
  • Herbivore tolerance to basal and novel defenses
  • Sequestration of plant toxins and higher-trophic interactions



  • Natural variation in the resistance of dandelion (Taraxacum officinale) to aphids
  • Physiological mechanisms of toxicity
  • Community ecology