ENT/BOT/ZOOL 473: Plant-Insect Interactions

ent473This course describes the multiple ways in which arthropods exploit plants, and how these interactions can affect plant growth, survival, and competition. Topics include plant traits that deter or augment insect behavior and development, insect behavioral and physiological counter adaptations, and environmental mediation of these interactions. Consequences of plant – herbivore interactions to insect population dynamics, plant succession & community ecology, and co-evolution are discussed. Implications of basic plant – insect interaction theory to natural resource management, environmental quality, and sustainable development are considered.

Course Overview

This course describes the many ways in which insects exploit plants, and how these interactions can benefit or adversely affect plant growth, survival, and competition.  Topics include plant traits that deter or augment insect behavior and development, insect behavioral and physiological counter adaptations, and environmental mediation of these interactions. Consequences of these interactions to insect population dynamics, plant succession and community ecology, and co- evolution are discussed.  We also consider the implications of basic plant-insect interaction theory to natural resource management, environmental quality, and sustainable development.

Course Format

We will meet 3 times per week, MWF 1:20 in Rm 104 Russell Labs. Most sessions will be lectures, but there will also be some discussion sessions, which will be in A121 Russell Labs.

Contacting Me

Please feel free to email me at any time. I prefer to respond by setting up a personal appointment rather than engaging in lengthy email discussions. I get a much better feel for how well students are grasping the material when I visit with them in person.


Reading the literature on plant – insect interactions constitutes a major portion of this course. How much you learn will depend largely on how well you prepare for lectures and discussions by doing the background readings. Please note that the syllabus includes both chapters from our text (Schoonhoven et al.) and peer-reviewed papers listed beneath the syllabus. All of these papers are on-line through Web of Knowledge.

Information from the readings will be included on exams from a conceptual but not detailed basis. For example, I might ask how two major scientists differ in their views of coevolution, and the bases for their arguments, but not minor pieces of data. So read these articles to get the major points the various authors are making,


Discussions are intended to help you understand some of the more controversial, conceptual, and timely topics in plant-insect interactions. They are an integral part of the course.

Each Discussion will be led by a group of students, but everyone is expected to participate. There is no Instructor’s role – I am simply a participant. Discussion leaders should email one paper to the class, one week before their assigned session. They should give a 15-minute presentation that sets the stage for discussion. Use this presentation to a) Give the background information needed for a substantive discussion; b) Identify what you perceive as the major knowledge gaps; c) pose key questions for the group. You may structure your topic as broadly or focused as you wish, and you may divide the roles of the discussion team any way you wish.

Please sign up for your topic no later than Feb. 1.

Each team should write a brief overview of their discussion area. This should be written along the lines of a “Trends in Ecology & Evolution” article. That is, describe the issue, provide the pertinent peer-reviewed references, identify the key knowledge gaps, and generate a synthesis. These should be no more than 6 single-spaced pages, plus 400-word Abstract and 2 pgs of references. You may include original figures within the text. You may cite web pages that provide pertinent data, but do not cite general web pages.


Assignment Weight
Midterm 1 25%
Midterm 2 25%
Midterm 3 25%
Discussion & Report 25%


+Click to view syllabus

Plant – Insect Interactions: Ent / Bot / Zool 473: Winter/Spring 2016
Kenneth Raffa

An Overview of Plant – Insect Interactions

Date Topic Reading1
Jan 20 Course objectives & mechanics; Overarching themes
Jan 22 Interspecific interactions 1
Jan 25 Diversity of interactions among plants and insects
Jan 27 Diversity of interactions, Direct and Indirect effects on plants
Biology, diversity and population dynamics of insects
Jan 29 Biology, diversity and population dynamics of insects
Feb 1 Biology, diversity and population dynamics of insects
Discussion Topic Choices Due

Plant Traits that Influence Utilization By Insects

Feb 3 Nutritional ecology of plant-feeding insects
Feb 5 Plant morphological defenses; Plant escape in space & time 3, 4, 5
Feb 8 Plant chemical defenses: N-containing compounds 6
Feb 10 Plant chemical defenses: Phenolics
Feb 12 Plant chemical defenses: Terpenoids
Feb 15 Theories of plant defense 7, 8, 9
Feb 17 Induced chemical defenses: Direct effects on herbivores 10, 11
Feb 19 Discussion: Can we construct a unifying theory of plant defense?
Feb 22 EXAM #1

Insect Traits that Facilitate Utilization Of Plants

Feb 24 Host selection behavior & Host specialization 12, 13
Feb 26 Behavioral & Ecological Adaptations for countering defenses 14, 15
Feb. 29 Morphological & Physiological Adaptations
March 2 Physiological Adaptations to Allelochemicals
March 4 Utilizing symbionts to exploit plants 16, 17
March 7 Discussion: How can we best use recent insights into symbioses to improve our understanding and utilization of plant-insect interactions?

Tritrophic Interactions in Plant Defense

March 9 Interactions with predators and parasites, pathogens 18,19, 20, 21
March 11 Interactions with pathogens, other herbivores 22, 23, 24
March 14 Discussion: How should we interpret induced plant defenses?
March 16 Interactions with plant symbionts: Endophytes and Mycorrhizae 25, 26
March 18 No class
March 28 EXAM #2

Plant – Insect Interactions in Plant Community Ecology and Evolution

March 30 Role of insect herbivores in Community Ecology, Succession, Disturbance 27
Apr 1 Role of insect herbivores in Community Ecology, Succession, Disturbance 28
Apr 4 Discussion: How can we best incorporate our knowledge of plant-insect interactions into broader theories of disturbance and ecosystem processes?
Apr 6 Insectivorous plants 30
Apr 8 Coevolution 31, 32, 33
Apr 11 Pollination ecology on landscapes: Claudio Gratton 29
Apr 13 Pollination ecology: Johanne Brunet
Apr 15 Discussion: How do selective pressures by insects drive patterns and processes of plant evolution?

Implications of Plant – Insect Interactions to Natural Resource Management

Apr 18 Application of plant – insect interactions to human welfare, environmental challenges, and natural resource management 34, 35
Apr 20 Responses to elevated temperature 36, 37
Apr 22 Response to elevated CO2: Rick Lindroth 38
Apr 25 Discussion: How will global climate change affect herbivory?
Apr 27 Invasive species 39
Apr 29 Discussion: How will global climate change affect insect biodiversity?
May 2 Discussion: Should genetic engineering be deployed in native ecosystems threatened by biological invasions?
May 4 Complex societal issues arising from plant- insect interactions
May 6 EXAM #3

1. Thompson, JN. 2009. The coevolving web of life. Amer. Nat. 173: 125-40.
2. Labandeira & Currano 2013. The fossil record of plant-insect dynamics. Ann. Rev. Earth Planet Sci. 41:
3. Bjorkman, C; Dalin, P; Ahrne, K. 2008. Leaf trichome responses to herbivory in willows: induction,
relaxation and costs. New Phytologist 179: 176-184.
4. Lucas-Barbosa D, van Loon JJ, Gols R, van Beek TA, Dicke M. 2013. Reproductive escape: annual
plant responds to butterfly eggs by accelerating seed production. Functional Ecology 27: 245-254.
5. Van Asch M & Visser ME. 2007. Phenology of forest caterpillars and their host trees. The importance
of synchrony. Ann. Rev Entomol. 52: 37-55.
6. Fraenkel, G. S. 1959. The raison d’être of secondary plant substances. Science. 129: 1466-1470
7. Feeny, P. 1976. Plant apparency and chemical defense Pp 1-40 In Wallace, J.W. & R.L. Mansell.
Recent Advances in Phytochemistry 10: Biochemical Interactions between Plants and Insects.
8. Coley, P. D.; Bryant, J. P.; Chapin, F. S. 1985. Resource availability and plant antiherbivore defense.
Science. 230: 895-899.
9. Herms D, Mattson WJ 1992. The Dilemma of Plants: To grow or defend. Quar Rev Biol. 67: 283-335.
10. Karban, R. 2010. The ecology and evolution of induced resistance against herbvivores. Func. Ecol. 25:
11. Thaler, JF, Humphrey PT & Whiteman NK. 2012. Evolution of jasmonate and salicylate signal
crosstalk. Trends in Plant Science 17: 260-270
12. Bernays, E. A. & O. Minkenberg. 1997. Insect herbivores – different reasons for being a generalist.
Ecology. 78: 1157-1169.
13. Barrett LG & Heil M. 2012. Unifying concepts and mechanisms in the specificity of plant-enemy
interactions. Trends in Plant Science 17: 1360-85.
14. Agrawal AA & Konno K. 2009. Latex: A model for understanding mechanisms, ecology, and evolution
of plant defense against herbivory. Ann. Rev. Ecol. Ecol. System. 40: 311-31.
15. Singer, MC & McBride C. 2010. Multi-trait host-associated divergence among sets of butterfly
populations: Implications for reproductive isolation and ecological speciation. Evolution 64: 921-33.
16. Douglas, A. E. 2009. The microbial dimension in insect nutritional ecology. Functional Ecology 23: 38-
17. Chung SH, Rosa C, Scully ED, Peiffer M, Tooker JF, Hoover K, Luthe DS, Felton GW. 2013.
Herbivore exploits orally secreted bacteria to suppress plant defenses. PNAS 110: 15728-33.
18. Barbosa P, Hines, J, Kaplan I, Martinson H, Szczpaniec & Szendrei 2009. Associational resistance and
associational susceptibility. Having right or wrong neighbors. Ann, Rev, Ecol. Evol. Syst, 40: 1-20.
19. Karban, R., I. T. Baldwin, K. J. Baxter, G. Laue & G. W. Felton. 2000. Communication between plants:
induced resistance in wild tobacco plants following clipping of neighboring sagebrush. Oecologia. 125:
20. Palmer et al. 2010. Synergy of multiple partners, including freeloaders, increases host fitness in a
multispecies mutualism. PNAS. 107: 17234-9.
21. Nishida R. 2002. Sequestration of defensive substances from plants by Lepidoptera. Ann. Rev. Ent. 47:
22. Turlings, T. C. J., J. H. Loughrin, P. J. Mccall, U. S. R. Rose, W. J. Lewis & J. H. Tumlinson. 1995.
How caterpillar-damaged plants protect themselves by attracting parasitic wasps. Proc. Nat Academy
Sciences USA. 92: 4169-4174.
23. Felton, GW; Tumlinson, JH: 2008. Plant-insect dialogs: complex interactions at the plant-insect
interface. Current Opinion In Plant Biology 11: 457-463.
24. Hunter, M. D. & Schultz, J. C. 1993. Induced plant defenses breached – phytochemical induction
protects an herbivore from disease. Oecologia. 94: 195-203.
25. Hartley SE & Gange AA. 2009. Impacts of plant symbiotic fungi on insect herbivores: Multualism in a
multitrophic context. Ann. Rev. Ent. 54: 323-42.
26. Bieri, A. P. S.; Harri, S. A.; Vorburger, C., et al. 2009. Aphid genotypes vary in their response to the
presence of fungal endosymbionts in host plants. J Evolutionary Biology 22: 1775-1780
27. Whiles MR & Charlton RE. 2006. The ecological significance of tallgrass prairie arthropods. Ann. Rev.
Ent. 51: 387-412.
28. Clay, NA, Lucas J, Kasparl M, & Kay AD. 2013. Manna from heaven: Refuse from an arboreal ant
links aboveground and belowground processes in a lowland tropical forest. Ecosphere 4: 1-15.
29. Jones, E, Bronstein J & Ferrier R. 2014. The fundamental role of competition in the ecology and
evolution of mutualisms. Annals NY Acad. Sci. 1256: 66-89.
30. Ellison AE & Gotelli NJ. 2001. The evolutionary ecology of insectivorous plants. Trends in Ecol &
Evol. 16: 623-9.
31. Berenbaum, M. R. 1983. Coumarins and caterpillars: A case for coevolution. Evol 37: 163-179.
32. Johnson MT, Smith SD & Rauscher MD. 2009. Plant sex and the evolution of plant defenses against
herbivores. PNAS 106: 18079-84.
33. Strauss, SY Y Irwin RE. 2004. Ecological and evolutionary consequences of multispecies plant-animal
interactions. Annu. Rev. Ecol Evol. System. 35: 435-66.
34. Meehan TD, Werling BP, Landis DA & Gratton C. 2012. Pest suppression potential of midwestern
landscapes under contrasting bioenergy scenarios. PlosOne 7 (7) e41728.
35. Tabashnik B, Brevault T & Carriere Y. 2013. Insect resistance to Bt crops: Lessons from the first billion
acres. Nature Biotechnology. 31: 510-21.
36. Parmesan, C. 2006. Ecological and evolutionary responses to recent climate change. Annual Review of
Ecology Evolution and Systematics 37: 637-669
37. Raffa KR, Powell EN & PA Townsend. 2013. Temperature-driven range expansion of an irruptive
insect heightened by weakly coevolved plant defenses. PNAS 110: 2193-2198.
38. Percy KE, Awmack CS, Lindroth RL, Kubiske ME, Kopper BJ, Isebrands JG, Pregitzer KS, Hendrey
GR, Dickson RE, Zak DR, Oksanen E, Sober J, Harrington R, Karnosky DF. 2002. Altered performance
of forest pests under atmospheres enriched by CO2 and O-3. Nature 420: 403-407.
39. Cappucini N & Carpenter D 2005. Invasive exotic plants suffer less herbivory than non-invasive plants.
Biology Letters 1: 435-438.