Insect coloration or how colour production in insect

3. colouration - appearance with regard to
colour. colour - a visual attribute of things
that results from the light they emit or
transmit or reflect or due to some pigments
or other factors.
 The signals thus produced may aid in
species identification and mate choice,
camouflage,
 warning, and temperature regulation, they
serve as a mute “language” with which an
individual organism may communicate its
place in the community within which it lives.

4.  Pigmentary /chemical colours
 Structural / physical colour
 Chemico-physical or combination of colours

5. Pigmentary and chemical colours:-
 Insects can make most of their pigments (some
apparently from waste products that were
historically simply stored or excreted), whereas
others must come from their diets. Several
general classes of pigments are recognized.
These differ in the color ranges they generate
and in the precursors used to produce them.
 Pigments appeared colour because these are
reflect certain colour of light and remaining are
absorbed and dissipated into heat.

6.  1.Melanin :-black and brown pigments occuring in insect
cuticle. They are often present. as granules in the exocuticle.
they are responsible for most of the dark patterning in the body
and wings. Dopamine and tyrosine are the precursor of
melanin.
 Eg. Diptera,adult and larval lepidoptera,coleoptera
 Pterins:-
 Pterins are white, yellow, or red pigments derived from a purine,
guanosine triphosphate. Some function as cofactors of
enzymes important in growth and differentiation They are also
cofactors in ommochrome production.
 eg- red colour of red cotton bug

7.  Ommochromes:-
 Ommochromes are red, yellow, or brown pigments derived
from tryptophan, which they may serve to use up if it is in
excess supply during times of high protein turnover (e.g., in
metamorphosis). They usually occur in granules coupled
with proteins and, are present as screening pigments in the
eyes as well as in the colors on the body.
 Eg:- xanthommatin in eye pigments, pink immature adult of
schistocerca due to the mixture of ommachrome,red
odonata and red ,brown nymphalid butterfly also.
 Papiliochromes are yellow and red/brown pigments
found only in butterflies in the family Papilionidae
 Quinone pigments are pigments of uncertain origin found
in the Homoptera
 Anthraquinones are found in members of the family
Coccidae, in which they give red and sometimes yellow
coloration

8.  Aphins are characteristic of aphids, to whom they impart a purple or black
coloration.
Eg. Erythroaphin in Aphis fabae , Eriosoma lanigera
 Billiverdin present in chironomid larva causing blue colour.
 Carotenoids:- These are the lipid soluble pigments carotene and
xanthophyll . Yellow ,orange and red colour are maily produced by
carotenoids it is depends upon the protein bounded. Insects can not
synthesize carotinoids must obtained from the diet. They are also sources of
retinal, a component of the photopigment of the eye. combination with blue
pigments ( bilins) they may produce an insect green, insectoverdin.
 Eg:- colorado potato beetle gets red and yellow coloured due
to beta- carotene in blood of colorado potato beetle obtained
from potato plants.

9. Red colour coccinellids is due to lycopene and alpha and beta
carotene.
Integument of locust contain Astaxanthin and beta carotene.
Flavonoids:-
Flavonoids are plant-derived pigments that produce cream or
yellow colors, particularly in the
Lepidoptera.(papilionidae,lycaenidae,satyridae insects)
Like the carotenoids, they cannot be synthesized but must come
from the diet.

10.  Structural and physical
colour:-
 Scattering :- due to scattering of light of
shorter wavelength blue colour seen
called tyndall blue as in odonata and blur
butterfly.
 scattering of small granules in the distal
region of epidermal cell
 It depends for its effect on an absorbing
layer of dark pigment beneath the fine
granules.in the absence of this layer the
blue is masked by the light reflected from

11.  Interferance:-
 Interfance colours result from the reflection of the light from a
series of superimposed surfaces separated by distances
comparable with the wavelengths of light.As a result of this
spacing,some wavelengths reflected from successive surfaces
are in phase and are therefore reinforced(“constructive
interference”); while others are out of phase and cancelled
out(“destructive interference”).the net result in that only certain
wavelengths are reflected and the surfaces appear coloured.
The results are the shimmering colors we call “iridescent.”
 Eg:- many butterfly (Morpho butterfly).

12.  Diffraction :-
 When a ray of light strikes the edges of a groove or ridge ,
different wavelengths are bent to varying degrees and white
light is split into its component spectral colours . if there is a
series of parallel grooves or ridges , separated by about the
wavelength of light, the wavelengths reflected from each line
interfere with each other. In a particular direction light of a given
wavelength is reinforced , while other wavelength are cancelled
out.
 Eg. Diffraction is responsible for the iridescence of some
beetles like carabid beetle, gyrinidae beetles

16. A.MULTI CELLULAR SPINE B.SETAE
C.THORNS D.MICROTRICHIA

17. Scales of
butterfly