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Insects and Plants

Butterflies and Plants:a study in coevolution

By Ehrlich & Raven

A classic!

CoevolutionReciprocal evolution

The hawk moth (Xanthopanmorganii) visiting the Madagascar Star Orchid (Angraecum sesquipedale)

(Illustration by Emily Damstra for the Smithsonian Institution)

Diana Marques

CoevolutionReciprocal evolution“Evolutionary arms race”

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How do plants and insect interact?1. Phytophagy (herbivory)2. Pollination and other behaviors affecting

plant reproduction3. Mutualisms involving insects residing in

plants

CoevolutionReciprocal evolution“Evolutionary arms race”

Feeding Guilds How to exploit the plant?

Chewing Sucking

Mining Boring

Galling

Galls

Gall Formers

~ 13,000 insect species (20 families, 7 orders) are known to induce galls.

Gall formers alter the development of the plant tissue to form a tumor-like growth, in which the insect gains nutrition and protection from the environment.

Spiked pea galls on rose

Robin's pincushion gall on wild roseSpangle Galls on oak

The species of insect that created the gall can often be determined by the shape and size of the gall.

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Galls

Galls can develop on any plant part

(leaf, stem, root, fruit, flower).

Goldenrod plant with Goldenrod Gall Fly, Eurosta solidaginis

Plant defenses

All organisms are potentially food for others.

Plants don’t passively let themselves get eaten!

How do they defend themselves?

Plant Defense Against Insect Herbivores

Defense Mechanisms

Structural Chemical

Insects

Affect the behaviour and physiology

InducedConstitutive Tolerance

Tolerance

Defense Mechanisms

Structural Chemical

Insects

Affect the behaviour and physiology

InducedConstitutive Tolerance

Plant Defense Against Insect Herbivores

Structural Defense

e.g. Trichomes

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Phaseolus vulgarisCommon bean

Defense Mechanisms

Structural Chemical

Insects

Affect the behaviour and physiology

InducedConstitutive Tolerance

Plant Defense Against Insect Herbivores

Chemical DefenseChemical defenses usually keep herbivores awayBut, sometimes they attract specialist herbivores!

Milkweed has cardiac glycosides that monarchbutterflies are able to sequester and use to defendthemselves

Milkweed beetleTetraopes tetrophthalmus(Coleoptera: Cerambycidae)

Chemical DefenseAlkaloidsCardiac glycosides (heart poisons)TanninsCyanideTerpenoidsLots more…

Reference Futuyma 1983

Taxol from Pacific Yew, Taxus brevifolia

Taxol was isolated from bark of Pacific Yew in 1970s. Taxol interferes with cell division by binding to the protein tubulin, a key factor in mitosis. Taxol and related compounds now widely used in treating breast and ovarian cancer.

Taxol, a terpenoid.

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Defense Mechanisms

Structural Chemical

Insects

Affect the behaviour and physiology

InducedConstitutive Tolerance

Plant Defense Against Insect Herbivores

Constitutive defense -always present

Constitutive vs. Induced Defenses

Induced defense - synthesized in response to challenge

Induced Defense : Talking PlantsWild tobacco and sagebrush Communication using methyl jasmonate

R. Karban, I.T. Baldwin, K.J. Baxter, G. Laue, G.W. Felton. Oecologia 2000

How do plants and insect interact?1. Phytophagy (herbivory)2. Pollination and other behaviors affecting

plant reproduction3. Mutualisms involving insects residing in

plants

Pollination and seed dispersal

Myrmecochory – seed dispersal by ants

Elaiosomes

NCSU

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How do plants and insect interact?1. Phytophagy (herbivory)2. Pollination and other behaviors affecting

plant reproduction3. Mutualisms involving insects residing in

plants

Plant ‘Rewards’ to HelpersThis is yet another way that plants can

defend themselves…

Food Bodies Domatia Extra Floral Nectaries

How can you tell if a plant structure is a domatia or a gall?

Acacia have tannins, spines, and ants

Acacia drepanolobiumTanzania and Kenya

Dr. Todd Palmer’s labin the Biology Department

http://web.mac.com/toadpalmer/Site/welcome.htmlhttp://web.mac.com/toadpalmer/Site/Mutualisms.html

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