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Andre Kessler

Associate Professor, Ecology and Evolutionary Biology

Director of Undergraduate Studies

Educational Background

Ph.D., Max Plank Institute for Chemical Ecology/University of Jena, Germany (2002)

M.A., University of Wurzburg, Germany (1988)

Website(s)

Overview

I am a chemical ecologist whose research focuses on the mechanisms, ecological consequences and the evolution of plant induced responses to herbivore damage. Conceptually, I study plant secondary metabolism as a vehicle of information transfer. Chemical information can mediate complex interactions from the molecular and cell to the whole plant and community level. As a consequence, my research includes studying chemical elicitation of plant responses, plant chemistry-mediated alterations in insect population and community dynamics, plant-plant communication, plant-pollinator interactions and plant defense mechanisms against herbivores. In my lab we use chemical and molecular tools in manipulative field and laboratory experiments to understand the mechanism of elicitation, signal transduction and information-mediating secondary metabolite production in plants responding to biotic and abiotic environmental stresses. Moreover, we put a particular emphasis on studying the ecological functions and evolution of plant metabolic responses and chemical information transfer in the plants’ native habitats. With more recent projects my group tries to apply some of the chemical ecology principles found in native systems to control insect pests in agricultural systems. My research includes a number of different study systems in New York, Utah, Peru, Costa Rica, Colombia and Kenya.  

I studied ecology, genetics and geobotany and received my masters degree at the University of Würzbug, Germany. I received my PhD (Dr.rer.nat.) from the Max Planck Institute for Chemical Ecology and University of Jena, Germany. 

I teach and co-teach in a number of courses, including BioEE 3611 Field Ecology, BioEE 3690 Chemical Ecology, BioEE 4460/4461 Plant Behavior, and BioEE 7640 Plant-Insect Interactions Seminar. 

Keywords

Chemical ecology, plant-animal interactions, plant resistance, herbivory, plant behavioral ecology, insect herbivory, plant-pollinator interactions, plant secondary metabolism

Departments/Programs

  • Ecology and Evolutionary Biology

Graduate Fields

  • Ecology and Evolutionary Biology
  • Entomology
  • Plant Biology

Research

Plants respond to biotic (e.g. herbivory, chemical cues from neighboring plants, pathogens) and abiotic stimuli (e.g. soil conditions, radiation, air pollution) with a bewildering array of transcriptional and metabolic changes. These changes as well as the constitutively expressed chemical phenotypes of the plant can function as information that mediates interactions of the plant with a complex network of organism. Our research focuses on studying the mechanisms, ecological consequences and evolution of plant induced responses to herbivore damage and the ecological functions of chemical information transfer.

More specifically, in wild Solanaceae species, such as wild tomatoes (Solanum spp.) we study the ecological relevance of herbivore-induced changes in flower metabolism and morphology and their effects on plant-herbivore pollinator dynamics. This research was recently expanded to include addressing the hypothesis that plant defensive strategies (e.g. constitutive vs. inducible resistance) and mating system (e.g. self-compatible vs self-incompatible) are co-evolving.

In tall goldenrod, Solidago altissima, a native of northeastern North American early succession habitats we study multiple aspects of plant chemistry-mediated interactions with a diverse arthropod community. This research includes the study of insect herbivores as agents of natural selection on plant chemical defenses, the ecological relevance and evolution of volatile organic compound-mediated plant-pant communication, the role of soil microbial communities in affecting plant metabolic phenotypes, and the interaction of ecological and evolutionary processes in affecting population and community dynamics, as well as structure and size of interaction networks.

In a number of plant species, we study the chemical elicitation processes and plant endogenous signal transduction that mediate specific plant responses to different herbivore species or chemical cues, such as volatile organic compounds.   

For all of our research we are using chemical and molecular tools in manipulative field and laboratory experiments to understand the mechanisms of elicitation, signal transduction and defensive secondary metabolite production in plants. The functional analysis of traits involved in the expression of induced plant responses of native species in their natural habitats may help to understand the evolution of plant defenses and eventually allows the utilization of the plants' own defenses in sustainable agriculture. In a recent project in collaboration with other Cornell faculty and the International Center for Insect Physiology and Ecology in Kenya, we apply chemical ecology principles to control insect pests of maize and Sorghum on smallholder farms in East Africa.

Most of our research is conducted in the field or greenhouses in New York, Utah, Peru, Costa Rica, Colombia and Kenya.  

Current Courses

Publications

  • Kessler, A. and M. Heil. 2011. The multiple faces of indirect defenses and their agents of natural selection. Functional Ecology DOI: 10.1111/j.1365-2435.2010.01818.x
  • Halitschke, R., J. Hamilton, and A. Kessler. 2011. Herbivore-induced plant vaccination. Part III: Herbivore-specific elicitation of phytosynthesis as a mechanism to compensate for herbivory.  New Phytologist (in press).
  • Mooney, K. A., R. Halitschke, A. Kessler, and A.A. Agrawal. 2010. Evolutionary tradeoffs in plants mediate the strength of trophic cascades. Science 327:1642-1644.
  • Parachnowitsch, A.L. and A. Kessler. 2010. Pollinators exert natural selection on flower size and floral display in Penstemon digitalis. New Phytologist 188:393-402.
  • Poveda, K., M.I. Gomez, and A. Kessler. 2010. The enemy as ally: herbivore-induced increase in crop yield. Ecological Applications 20:1787-1793.
  • Kessler, A. and R. Halitschke. 2009. Testing the potential for conflicting selection on floral chemical traits by pollinators and herbivores: Predictions and case study. Functional Ecology 23:901-902.
  • Kessler, A. and R. Halitschke. 2007. Specificity and complexity: The impact of herbivore-induced plant responses on arthropod community structure. Current Opinion in Plant Biology 10:409-414.
  • Kessler, A. and I.T. Baldwin. 2004. Herbivore-induced plant vaccination. Part I. The orchestration of plant defenses in nature and their fitness consequences in the wild tobacco Nicotiana attenuata. Plant Journal 38:639-649.
  • Kessler, A., R. Halitschke, and I.T. Baldwin. 2004. Silencing the jasmonate cascade: Induced plant defenses and insect populations. Science 305:665-668.
  • Kessler, A. and I. T. Baldwin. 2001. Defensive function of herbivore-induced plant volatile emissions in nature. Science 291:2141-2144.