S.Camazine MTFrazier Insects: Dressed for Success.

S.CamazineMTFrazier

MTFrazier

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

MTFrazier

1) Morphological:

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

MTFrazier

…but it doesn’t work from every angle!

MTFrazier

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

MTFrazier

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

Scott Camazine

2) Chemical:

PheromonesToxins: sequestered or produced

Venoms

S. Camazine

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:

MTFrazier

MTFrazier

3) Behavioral:DIY ‘House Building’

MTFrazier

MTFrazier

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

S. Camazine

MTFrazier

Camouflage = primary defenseChemicals = secondary defense

MTFrazier

It’s not enough to look like a twig (or thorn, stick, etc.)

You have to ‘act’ like one to survive!

Camouflage +

Behavior

MTFrazier

This caterpillar is even MORE ‘painful’ than it looks

mechanical + chemical

S. Camazine

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