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Insects:Dressed for

Success

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 arsenalof defense mechanisms

Insects have an arsenalof defense mechanisms

• Morphological / Physical

• Chemical

• Behavioral

Insects have an arsenalof defense mechanisms

• Morphological / Physical– camouflage (crypsis)– mimicry– mechanical

• Chemical

• Behavioral

Insects have an arsenalof defense mechanisms

• Morphological / Physical– camouflage (crypsis)– mimicry– mechanical

• Chemical– toxins– venoms– pheromones

• Behavioral

Insects have an arsenalof defense mechanisms

• Morphological / Physical– camouflage (crypsis)– mimicry– mechanical

• Chemical– toxins– venoms– pheromones

• Behavioral– death feigning– “house” construction

CamouflageBlend into their background by looking like their background

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1) Morphological:

Blend into their background bybreaking up their body outline (disruptive coloration)

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…but it doesn’t work from every angle!

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Blend into their background bylooking like some uneatable part of their background

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Monarch butterfly = toxic

Viceroy butterfly = aposematically "dressed" because it doesn’t have the chemical toxins

1) Morphological:Mimicry

Aposematism: warning coloration

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

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2) Chemical:

PheromonesToxins: sequestered or produced

Venoms

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S. Camazine

S. Camazine

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

Aposematic coloration = primary defenseVenoms and toxins = secondary defense

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Camouflage = primary defenseChemicals = secondary defense

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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

mechanical + chemical

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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

ReviewInsect Defense Mechanisms:

• Morphological / Physical– camouflage (crypsis)– mimicry– mechanical

• Chemical– toxins– venoms– pheromones

• Behavioral– death feigning– “house” construction