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Richard Karban John Dryburgh ‘Personal’ History • B.S. at Haverford College, PA • Ph.D. at University of Pennsylvania • Currently at UCDavis • Co-wrote “How to Do Ecology” and “Induced Responses to Herbivory” • ~142 journal articles and 7 book chapters Plant Behavior & Herbivory • Plants respond to their environment – Abiotic factors – Biotic factors – Other plants Karban, 2008 Plant Defense Against Herbivory • a Induced Resistance • Phenotypic plasticity in which herbivore attack causes an increase in resistance to future herbivore attack – Includes physical, chemical, and biological mechanisms, ‘tolerance’ Karban, 2011 Effects of Induced Resistance • Herbivores – Alters feeding behavior – Decreases growth rate – Affects host selection – Death? (Natural enemies) • Plants – Fitness costs – Fitness benefits Karban and Myers, 1989 Why Induce Resistance? • Less costly? • “Defended Fortresses” vs. “Moving Targets” • Are plants in nature ‘constantly induced?’ Adler and Karban, 1994; Karban and Myers, 1989 Costs of Resistance • Is resistance costly? – Phytotoxicity of defenses – Resource allocation • Difficult to measure experimentally Adler and Karban, 1994; Karban and Myers, 1989 Evading Herbivores • “Defended Fortresses” vs. “Moving Targets” • Creates variance in environment • Variability reduces herbivore performance Adler and Karban, 1994; Karban et al, 1997 Are Plants Always Induced? • Wide variety of inducers – Biotic and abiotic • Plants in the field may always be effectively induced Applications in Agriculture • Spider mites in grape – ‘Vaccinating’ against Pacific spider mites • Jasmonic acid Karban et al, 1991 Jasmonic Acid • Plant hormone • Involved in plant responses to herbivores • Antagonistic to salicylic acid (“Crosstalk”) Defense Against Herbivores • JA and MeJA induce similar responses to herbivory in tomato – Induce proteinase inhibitors, lipoxygenase, et al – Suppress herbivore populations • ‘Cross talk’ with salicylic acid Thaler et al, 2001; Thaler et al, 1995 Eavesdropping • “Talking Trees” hypothesis • Plant volatiles: VOC, green leaf volatiles, and HIPV • Can plants talk? To whom? – Inter- and intra specific eavesdropping Sagebrush and Wild Tobacco • Inter- and intra specific eavesdropping – Sagebrush volatiles induce resistance in neighboring sagebrush • Also induces insect resistance in neighboring tobacco – Net fitness benefit? – Other effects? Various Karban et al. Evolution of Eavesdropping • Volatiles as within-plant signaling? • Signaling natural enemies? • Kin selection? Baldwin et al, 2006 Intra-plant Signaling and Kin Selection • Sagebrush responds more strongly to cues from genetically identical cuttings – ‘Recognition of self’ • Possibly faster than vascular signaling Karban and Shiojiri, 2009 Natural Enemies • Purely physiological process – Volatiles exploited by natural enemies • “Deliberate” process – VOC also induce traits such as EFN, direct defense – ‘Synergistic interactions’ among defenses Heil and Karban, 2009 Cipollini and Heil, 2010 Current Work • Volatile communication • What factors affect caterpillar densities? – Parasitoids/predation – Weather patterns – Food resources • 29 years of census data • Dare to be naive. I think we are limited in science (and life) by trying to be experts and being unwilling to take chances and in many cases to look dumb. By daring to be naive, you are willing to put yourself out there, ask questions that you think everyone else already knows the answers to, stuff like that. Questions? References and Photo Credits Photo Credits: – • Slides 2, 15, 20, 22: Karban lab website; karban.wordpress.com Slide 4:Arab, A., and Bento, J.M.S. Plant Volatiles: New Perspectives For Research in Brazil. 2006, Holopainen, J.K., and Gershenzon, J. Multiple Stress Factors and the Emission of Plant VOCs. 2010, Michelle Sherwood (http://michellesherwood.blogspot.com), Wikipedia – – Slide 19: Cipollini, D, and Heil, M. Costs and Benefits of Induced Resistance to Herbivores and Pathogens in Plants. 2010 Slide 16: Baldwin I.T. et al Volatile Signaling in Plant-Plant Interactions: Talking Trees in the Genomics Era References: – – – – – – – – – – – – – – – Adler, Frederick R. and Richard Karban. Defended fortresses or moving targets? Another model of inducible defenses inspired by military metaphors. The American Naturalist, 144(5): 813-832. 1994 Heil, M. and R. Karban. Explaining the evolution of plant communication by airborne signals. Trends in Ecology and Evolution, 25: 137-144. 2010 Karban, R. Communication between sagebrush and wild tobacco in the field. Biochemical Systematics and Ecology, 29: 995-1005. 2001 Karban, R. Plant behaviour and communication. Ecology Letters, 11: 727-739. 2008 Karban, Richard, Anurag A. Agrawal, and Marc Mangel. The benefits of induced defenses against herbivores. Ecology, 78(5): 1351-1355.1997 Karban, R., I.T. Baldwin, K.J. Baxter, G. Laue, and G.W. Felton. Communication between plants: induced resistance in wild tobacco plants following clipping of neighboring sagebrush. Oecologia, 125: 66-71. 2001 Karban, Richard, Gregory English-Loeb, and David Hougen-Eitzman. Mite vaccinations for sustainable management of spider mites in vineyards. Ecological Applications. 7(1): 183-193. 1997 Karban, Richard, Gregory English-Loeb and Paul Verdegaal. Vaccinating grapevines against spider mites. California Agriculture, 45(1): 19-21. 1991 Karban, Richard and Judith H. Myers. Induced plant responses to herbivory. Annual Reviews of Ecology and Systematics, 20: 331-348. 1989 Karban, R., J. Maron, G.W. Felton, G. Ervin, and H. Eichenseer. Herbivore damage to sagebrush induces resistance in wild tobacco: evidence for eavesdropping between plants. Oikos, 100: 325-332. 2003 Karban, R., K. Shiojiri, M. Huntzinger, and A. C. McCall. Damage- induced resistance in sagebrush: volatiles are key to intra- and interplant communication. Ecology, 87: 922-930. 2006 Karban, R. and K. Shiojiri. Self recognition affects plant communication and defense. Ecology Letters, 12: 502-506. 2009 Thaler, Jennifer S., Michael J. Stout, Richard Karban, and Sean S. Duffey. Exogenous jasmonates simulate insect wounding in tomato plants (Lycopersicon esculentum) in the laboratory and field. Journal of Chemical Ecology, 22(10): 1767-1781. 1996 Thaler, J.S., M.J. Stout, R. Karban and S.S. Duffey. Jasmonate-mediated induced plant resistance affects a community of herbivores. Ecological Entomology, 26: 312-324. 2001 Thaler, J.S., R. Karban, D.E. Ullman, K. Boege, and R.M. Bostock. Cross-talk between jasmonate and salicylate plant defense pathways: effects on several plant parasites. Oecologia, 131: 227-235. 2002