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INSECT COLOUR & COLOURATION

Colouration & Importance of colourVISHNU G.

Colourational Defense

1. Crypsis Colouration that makes animals difficult to distinguish against their backgroundCrypsis works only if the animal is resting on the appropriate background and usually only when the animal is not moving

3

HomochromismSimilarity of animals to the colour of inanimate objects

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

HomomorphismSimilarity 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 objectsSame 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 behaviorDynamic, frightening or startle behaviorDisplay of some conspicuous colour or structureStatic displayDeep red or black hind wingPraying mantids & PhasmidsPhymateus sp, Smerinthus ocellatus, Aglais io

Shock

Smerinthus ocellatusAglais ioPhtmateus spPyrgomorphidaeSurprise !!!Surprise !!!

3. Warning colouration Aposematism The correlation between conspicuous signals, such as bright colouration & prey unprofitability Candy Rowe, 2001

Brightly Coloured Species Puzzle for BiologistHenry Walter

Sexual selection 1866Historic approach

1862

Pseudosphinx hawk moth caterpillar

Experimental proof

1867

Unpalatable species1866Aposematism

1890

Aposematic insectsSpeciesStage ColourBasis of unpalatabilityZonocerus variegatusAdultB/Y & R markingsVarious chemicalsRomalea guttataAdultB/R hind wingsVarious chemicalsAphis neriiAllBright yellowCardiac glycosidesOncopeltus fasciatusAdultY/B spotsCardiac glycosidesCoccinella septemfasciataAdultR/B spotsAlkaloidsHycleus lugensAdultYellow spotsAlkaloidsVespula vulgarisAdultY/B stripesStingTyria jacobaeaeLarvaB/Y stripesPyrrolizidine alkaloidsTyria jacobaeaeAdultB/R marksPyrrolizidine alkaloidsDanaus plexippusLarvaW/B & Y stripesCardiac glycosidesZygaena filipendulaAdultB/R spotsCyanogenic glycosides

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

Orthoptera

Zonocerus variegatusRomalea guttataReference - The insects structure & function (2011): R. F. Chapman

Hemiptera

Aphis neriiOncopeltus fasciatusReference - The insects structure & function (2011): R. F. Chapman

Coleoptera

Hycleus lugensCoccinella septemfasciataReference - The insects structure & function (2011): R. F. Chapman

Hymenoptera

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

Larval Lepidoptera

Tyria jacobaeaeDanaus plexippusReference - The insects structure & function (2011): R. F. Chapman

Lepidopteran adult

Tyria jacobaeaeZygaena filipendulaReference - The insects structure & function (2011): R. F. Chapman

4. MimicryResemblance of one species to another I am someone elseRelated to Camouflage

DefensiveAggressiveAuto/Self

Defensive/ Protective mimicryIt 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 elseBatesian mimicryMullerian mimicryMartensian/ Emsleyan mimcryWasmannian mimicry

Batesian mimicryA harmless mimic poses as harmful A sheep in wolfs clothingAlso known as Parasitic mimicryMimic - emits signals similar to model but does not possess the attributes that makes it unprofitable to predators

Henry Walter Bates

British naturalist ,23

MimicModelNormalMimicModelNormal

Hypolimnas missipus Danaid egg fly, Plain Tiger Danaus plexippusHypolimnas bolina - Great Egg Fly , Common Crow Euploea core24

Mullerian mimicryTwo harmful species share similar perceived characteristics Mutualistic mimicry or ConvergencePredation on any one species is reducedWhen 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

Named after German naturalist Fritz Muller

25

Heliconius sp.Phonoctonus sp.Dysdercus sp.

Wasmannian mimicryThe mimic resembles a model along with which it lives as an inquiline in a nest or colonyMost of the models here are social insects such as ants, termites, bees & wasps

Erich Wasmann

Araeoschizus spReichenbachia spatulifer

Mertensian/ Emsleyan mimicryNamed after M. G. Emsley & German herpetologist Robert MertensA deadly mimic resembles a less harmful but lesson-teaching model

Robert Mertens

Aggressive mimicryAlso known as Peckhamian mimicry after George & Elizabeth PeckhamPredators or parasites which share characteristics with a species harmless to their prey, allowing them to avoid detection by the latterMimic may resemble the prey or host itselfThe model may be affected vely, +vely or neutral

Automimicry/ Interspecific mimicryThe species relationship between model & mimicOccurs within a single species one case being where one part of an organisms body resembles another partMimic 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 aetolusCycnus phalerosRekoa palegonAtlides atysCalycopis isobeon

ReferencesChapman, 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