Topic Compound Eyes Of Entomology 1 Contents

Topic Compound Eyes Of Entomology 1

Contents • • • Receptors in Insects Photoreception in Insects Compound Eyes Ommatidia Components of Ommatidia Photochemistry of Insect vision Forms of Compound Eyes Significance of Compound Eyes Color vision in Some Orders Of Insects • Summary • References

Receptors in Insects • • Mechanoreceptors Auditory receptors Stretch receptors Chemoreceptors Olfactory receptors Gustatory receptors Thermo receptors Photo receptors

• Photoreception in Insects Vision is the perception of light. Roles of vision in insects Entomology 4

Photoreception in Insects • Photoreceptors: 1. Ocelli. 2. Stemmata 3. Compound eyes

Dorsal ocelli Ø Ø Ø In larvae of hemimetabolous insects and in nearly all adults. Poor perception of form. Active in orientation to a light source. Ref. 02 6

Stemmata n n n In larvae of holometabolous insects Do not produce clear images Most caterpillars can discriminate some shapes and they can orientate themselves with respect to boundaries. 7

Compound Eyes: n n Most adult insects have a single pair of compound eyes. Reduced or absent in parasitic forms, many soil insects, and in some species that live in very dark places. 8

Compound Eyes and ocelli 9

Facet: Hexagonal Components of Compound Eye. Entomology 10

Ommatidia v Basic unit of compound eyes v Vary in size and number. • Honey bee has 4900 Ommatidia in Queen, 6300 in workers and 13000 in donors. • Pomera punctatissima have only one ommatidium in each eye. v The sizes of Ommatidia vary from about 5 to 40 microns in diameter. Ref. 02

Components of Ommatidia v Optical parts: 1. Corneal lens 2. Crystalline cone v Sensory parts: 1. Retinula cells 2. Rhabdom v A nerve axon projects from each retinula cell. v Optic nerve (YADAV. M) Ref. 01

Compound Eyes and Brain 13

Photochemistry of Insect vision • Photons are caught on the rhabdome by retinal. • Retinal is connected to opsin, forming rhodopsin. • On absorption of photon, retinal changes its form from bent to straight. • When retinal changes its form, it separates from the rhodopsin and the opsin triggers a nerve cell. • The nerve cells conduct the signal to the brain. Ref. 02 14

Forms of Compound Eyes 1. Apposition eyes 2. Superposition eyes. Ref. 01 15

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Significance of Compound Eyes 1. Flicker effect The compound eye is excellent at detecting motion. As an object moves, ommatidia are turned on and off. Ref. 03 17

Significance of Compound Eyes 2. Distance Perception Ø Most insects must be able to judge distance. Ø As in prey catching insects, in Grass hopper’s jumping, and when they are landing. Ø Simultaneous stimulation of ommatidia. Ref. 01 18

Colors

Significance of Compound Eyes 3. Color vision • • • Some insects are able to distinguish colors Most flower visiting insects exhibit preferences for blue and yellow. Important in feeding and in court ship behavior 20

3. Color vision Bichromatic Insects. One pigment absorbs green and yellow light (550 nm); the other absorbs blue and ultraviolet light (<480 nm). Trichromatic Insects. Absorption maxima at 360 nm (UV), 440 nm (blueviolet), and 588 nm (yellow) 21

Human Vision Vs. Insect Sight n n Colors visible to insects is higher in frequency (lower in wave length) Violet light is the highest frequency of color humans can detect, but many insects can see a higher frequency of light invisible to us, ultraviolet light. REF 04 22

Ultraviolet vision Entomology 23

Color vision in Some Orders Of Insects

1. Vision in Order Hymenoptera n n n n Eastern honey bee (Apis cerana). Family: Apidae The bees are red-blind. “orange, yellow, and green are the same color” – yellow. Sensitive to UV light. They see blue colors best. Sense of polarization of visible light in the sky. Ref. 05

2. Vision in Order Odonata ØDragonfly(C. aenea) or Downy emerald ØFamily: Corduliidae ØCompound eyes with wide-angle vision ØTheir eyes do not move. Ø 30, 000 eye ommatidia ØOrange to ultraviolet (UV) light. ØAble to estimate distance based on the distance between their eyes. Ref. 06

3. Vision in Order Diptera ØHouse flies (Musca domestica) ØFamily: Muscidae ØThe vision of the housefly is blurred ØCompound apposition eyes ØCan sense rapid motion approaching 200 cycles per second. Ref. 06

Vision in Mosquito n n Mosquito (Culiseta longiareolata) Family: Culicidae Mosquitoes are attracted to black and to dark colors. (Howlett 1910) Prefer the corners of a three-dimensional target. (Brown & Bennett) Ref. 07

4. Vision in Order Coleoptera n n Beetle (Tetraopes tetrophthalmus) Family: Cerambycidae Have infrared detection systems for night vision, fire detection, and other functions as to sense forest fires. Beetles have refraction superposition eyes Ref. 06

5. Vision in Order Blattaria n n American cockroach (Periplaneta americana), Family: Blattidae 2000 individual lenses Has receptors for UV light and green light. Ref. 08

6. Vision in Order Homoptera Aphids Super family: Aphidoidea Contains green, blue, and ultraviolet photoreceptors Ref. 09

7. Vision in Order Lepidoptera n Butterfly(Papilio rutulus) n Family: Papilionidae n Can See simultaneously in every direction. Trichromatic vision It can distinguish night from the day Can perceive colors in a high frequency n n n (from 310 nm to 700) Ref. 10

Vision in Order Lepidoptera Ø Gipsy Moth (Lymantria dispar). Ø Family: Lymantriidae Ø Can see in the back of their heads. Ø Neural summation Ø Have three types: blue, green, and ultraviolet. Ref. 12 Ø Ultraviolet light reflection.

Summary n Compound Eyes of Insects

References 1. 2. 3. 4. 5. 6. 7. YADAV. M, "Physiology of Insects, " Discovery Publishing House New Delhi-110002, pp. 322 -345 http: //entomology. unl. edu/ent 801 home. html http: //users. rcn. com/jkimball. ma. ultranet/Biology. Pages/ C/Compound. Eye. html www. cals. ncsu. edu/course/ent 425/tutorial/colorvision. h tml http: //www. sewanee. edu/Chem&Art/Detail_Pag es/Color. Projects_2003/Crone www. eyedesignbook. com/index. html http: //www. ent. iastate. edu/dept/research/vandyk/hosts eek. htm

References 8. http: //www. sciencemag. org/cgi/content/ab stract/171/3977/1254 9. http: //www. ncbi. nlm. nih. gov/pmc/articles/P MC 1945073/figure/pbio-0050187 -g 003 10. http: //www. butterflyzone. org/butterflyarticles/butterfly-uv-vision. shtml 11. http: //indianapublicmedia. org/amomentof science/insect-color-vision 12. http: //www. animalcorner. co. uk/insects/m oths/moth. html

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