insect colouration

Colouration & Importance of colour

VISHNU G.

Colourational Defense

• I am some one else

• I am not tasty

• I am dangerous

• I am not here

Cryptic colourat

ion

Revealing

colouration

MimicryWarning colourat

ion

1. Crypsis

Colouration that makes animals difficult to distinguish against their background

Crypsis works only if the animal is resting on the appropriate background and usually only when the animal is not moving

HomotypismHomomorphismHomochromism

Homochromism

• Similarity of animals to the colour of inanimate objects

• These insects are often the same colour as the leaves or twigs on which they rest

Homomorphism

Similarity of animals to the form of inanimate objects

These insects are often the same form as the leaves or twigs on which they rest

Homotypism

• Similarity of animals to the colour & form of inanimate objects

• Same colour & form as the leaves or twigs on which they rest

The South Indian Blue OakleafKallima horsfieldii, Nymphalidae

2. Revealing colouration

Deimatic behavior

Any pattern of threatening or startling behavior

such as,

suddenly displaying conspicuous eye spots - to scare

off or momentarily distract a predator thus giving the prey

animal an opportunity to escape

Deimatic behavior

• Dynamic, frightening or startle behavior

• Display of some conspicuous colour or structure

• Static display

• Deep red or black hind wing

• Praying mantids & Phasmids

• Phymateus sp, Smerinthus ocellatus, Aglais io

Shock

Smerinthus ocellatus

Aglais ioPhtmateus spPyrgomorphidae

Surprise !!!

Surpris

e !!!

3. Warning colouration

Aposematism

The correlation between conspicuous signals, such as

bright colouration & prey unprofitability

Candy Rowe, 2001

Brightly Coloured Species – Puzzle for Biologist

Henry Walter

Sexual selection 1866

Historic approach

1862

Pseudosphinx hawk moth caterpillar

Experimental proof

1867

Unpalatable species

1866

Aposematism

1890

Apos

emat

ic co

lour

atio

n

Brightly Coloured Species – Puzzle

for Biologist

Antipredator adaptation

Advertising signal

Exploited in Mullerian mimicry

Greek word – Apo = Away & Sema =

Sign Signs that warn other animals

away

Aposematic insectsSpecies Stage Colour Basis of unpalatability

Zonocerus variegatus Adult B/Y & R markings Various chemicals

Romalea guttata Adult B/R hind wings Various chemicals

Aphis nerii All Bright yellow Cardiac glycosides

Oncopeltus fasciatus Adult Y/B spots Cardiac glycosides

Coccinella septemfasciata Adult R/B spots Alkaloids

Hycleus lugens Adult Yellow spots Alkaloids

Vespula vulgaris Adult Y/B stripes Sting

Tyria jacobaeae Larva B/Y stripes Pyrrolizidine alkaloids

Tyria jacobaeae Adult B/R marks Pyrrolizidine alkaloids

Danaus plexippus Larva W/B & Y stripes Cardiac glycosides

Zygaena filipendula Adult B/R spots Cyanogenic glycosides

Reference - The insects structure & function (2011): R. F. Chapman

Orthoptera

Zonocerus variegatus

Romalea guttata


Hemiptera

Aphis nerii

Oncopeltus fasciatus


Coleoptera

Hycleus lugens

Coccinella septemfasciata


Hymenoptera

Vespula vulgaris


Larval Lepidoptera

Tyria jacobaeae

Danaus plexippus


Lepidopteran adult

Tyria jacobaeae

Zygaena filipendula


4. Mimicry

• Resemblance of one

species to another

• I am someone else

• Related to Camouflage

Defensive

Aggressive

Auto/Self

Defensive/ Protective mimicry

• It takes place when organisms are able to avoid an

encounter that would be harmful to them by deceiving an

enemy into treating them as something else

Batesian mimicry

Mullerian mimicry

Martensian/ Emsleyan mimcry

Wasmannian mimicry

Batesian mimicry

• A harmless mimic poses as harmful

A sheep in wolf’s clothing

• Also known as Parasitic mimicry

• Mimic - emits signals similar to model but does not possess

the attributes that makes it unprofitable to predators

Henry Walter Bates

Mimic ModelNormal

Mimic ModelNormal

Mullerian mimicry

• Two harmful species share similar perceived

characteristics

• Mutualistic mimicry or Convergence

• Predation on any one species is reduced

• When two poisonous species have similar markings; fewer

insects need to be sacrificed in order to teach the predators

not to eat these unpalatable animals

Fritz Muller

Heliconius sp.

Phonoctonus sp.

Dysdercus sp.

Wasmannian mimicry

• The mimic resembles a model along with which it lives as an inquiline in a nest or colony

• Most of the models here are social insects such as ants, termites, bees & wasps

Erich WasmannAraeoschizus sp Reichenbachia spatulifer

Mertensian/ Emsleyan mimicry

• Named after M. G. Emsley & German herpetologist Robert

Mertens

• A deadly mimic resembles a less harmful but lesson-

teaching model

Robert Mertens

Aggressive mimicry

• Also known as Peckhamian mimicry after George &

Elizabeth Peckham

• Predators or parasites which share characteristics with a

species harmless to their prey, allowing them to avoid

detection by the latter

• Mimic may resemble the prey or host itself

• The model may be affected –vely, +vely or neutral

Automimicry/ Interspecific mimicry

• The species relationship between model & mimic

• Occurs within a single species one case being where one

part of an organism’s body resembles another part

• Mimic imitates other morphs within the same species

• Deflection marks in Lycaneid butterfly

Deflection marks

Deflection marks are those which divert the attack of a

predator away from the most vulnerable part of an animal

to where it will do minimal damage

Polycephalic Butterflies

Arawacus aetolus

Cycnus phaleros

Rekoa palegon

Atlides atys Calycopis isobeon

References

Chapman, R. F. (2011). Visual signals: Colour and light production. The insects structure & function (4th edition), pp. 657-679.

Robert K. Robbins, The American Naturalist. The “False Head” Hypothesis: Predation and Wing Pattern Variation of Lycaenid Butterflies. Vol. 118, No. 5 (Nov., 1981), pp. 770-775

insect colouration

Science