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 CreditsPhoto 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