S.Camazine
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Insects:
Dressed for Success
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Insects are the smorgasbord
of the animal world!
Who Eats Insects?
Who Eats Insects?
•
•
•
•
•
•
•
•
birds
fish
arthropods (insect and non-insect)
amphibians
mammals
reptiles
humans
even plants!
Do insects take
this lying down?
Insects have an arsenal
of defense mechanisms
Insects have an arsenal
of defense mechanisms
• Morphological / Physical
• Chemical
• Behavioral
Insects have an arsenal
of defense mechanisms
• Morphological / Physical
– camouflage (crypsis)
– mimicry
– mechanical
• Chemical
• Behavioral
Insects have an arsenal
of defense mechanisms
• Morphological / Physical
– camouflage (crypsis)
– mimicry
– mechanical
• Chemical
– toxins
– venoms
– pheromones
• Behavioral
Insects have an arsenal
of defense mechanisms
• Morphological / Physical
– camouflage (crypsis)
– mimicry
– mechanical
• Chemical
– toxins
– venoms
– pheromones
• Behavioral
– death feigning
– “house” construction
1) Morphological:
Camouflage
Blend into their
background by looking
like their background
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Blend into their background by
breaking up their body outline (disruptive coloration)
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…but it doesn’t work
from every angle!
Blend into their background by
looking like some uneatable part of their background
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1) Morphological:
Mimicry
Aposematism:
warning coloration
Monarch butterfly = toxic
Viceroy butterfly = aposematically "dressed"
because it doesn’t have the chemical toxins
Looks like a bee, BUT this is actually a fly!
Bee-mimic = No venom to back up aposematism
Mimicry:
• Batesian - the aposematic inedible
model (monarch) has an edible mimic
(viceroy)
- the model suffers, aposematic signal is
diluted
Mimicry:
• Müllerian - both the model and the
mimic are distasteful
- all benefit from co-existence because
predators associate all aposematic color
individuals as toxic
1) Morphological:
Mechanical
Scott Camazine
Venoms
2) Chemical:
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S. Camazine
Toxins: sequestered or
produced
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Pheromones
Chemically defended insects are typically very
apparent to their predators: warning colors
S. Camazine
S. Camazine
Where do insects get their toxins?
3) Behavioral:
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3) Behavioral:
DIY ‘House Building’
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These defense mechanisms often
work in combination:
Toxins and venoms + aposematic coloration
(or sometimes camouflage)
Camouflage + behavior
Mechanical + chemical
In some cases toxins and venoms
can be costly for insects to produce
S. Camazine
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Aposematic coloration = primary defense
Venoms and toxins = secondary defense
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Camouflage = primary defense
Chemicals = secondary defense
It’s not enough to look like a twig (or thorn, stick, etc.)
You have to ‘act’ like one to survive!
Camouflage
+
Behavior
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This caterpillar is even MORE ‘painful’ than it looks
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mechanical + chemical
How did these defenses come about?
Evolution
By the process of
Natural Selection
Governing principles of Natural Selection
• Populations of species have variability
• Variation is maintained by sexual reproduction
• Variations can be passed from one generation to the next
• Individuals that have variations (traits) that make them
better able to survive (adapted) in their environment are
more likely to survive and pass on their variation
(traits/genes) to the next generation
Camouflage in caterpillars
First Generation
Second Generation
?
Third Generation
Other factors, in addition to natural selection,
influence how species evolve over time:
• Mutations
• Genetic isolation
Review
Insect Defense Mechanisms:
• Morphological / Physical
– camouflage (crypsis)
– mimicry
– mechanical
• Chemical
– toxins
– venoms
– pheromones
• Behavioral
– death feigning
– “house” construction