INSECT COLORATION

Insect coloration or how colour production in insect

1. A PRESENTATION ON COLORATION OF INSECTS AND INTEGUMENTARY STRUCTURES SUBMITTED BY:- SAROJ SAHOO M.SC(ENTOMOLOGY )

2. Colouration in insects

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 Factors for colouration :-

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 the background .

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

13. Cuticular extension or processES

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

15. Scales of butterfly