insects and plants - institute of food and agricultural...
TRANSCRIPT
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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