Aaliya Afroz Ph. D. Scholar Department of Entomology, Indira Gandhi Krishi Vishwavidayalaya Raipur, (C.G)

1. VISION AND VISUAL
NAVIGATION IN
NOCTURNAL INSECTS
Seminar Incharge
Dr. S. S. Shaw and
Dr. Y. K. Yadu
Professor
Speaker
Aaliya Afroz
Ph. D. Scholar
Department Of Entomology, IGKV (Raipur)

2. Introduction
With the help of compound eyes, insects recognize and react to
Ø conspecifics;
Ø distinguish and avoid predators;
Ø locate food sources and intercept prey;
Ø navigate;
Ø walk, swim, or fly through a complicated three-dimensional habitat.
Warrant and Dacke, 2011

3. Visual System In Insects
1. Simple eyes (Ocelli)- can only detect changes in light level.
(b) Lateral ocelli (Stemmata)-
larvae of holometabolous
(a) Dorsal ocelli –
nymphs of hemimetabolous, all adult insect

4. 2. Compound Eyes

5. HOW IS SUCH IMPRESSIVE VISUAL PERFORMANCE
ACHIEVED IN NOCTURNAL INSECTS?
v Behavioral modifications (such as slower locomotion)
v Optical designs of most nocturnal compound eyes
Active exclusively at night, when light levels can be up to 11 orders of magnitude
lower
Nocturnal insects -
Warrant and Dacke, 2011

6. Nocturnal Insects

7. Eyes And Vision In Nocturnal Insects
Ø Eyes with an enhanced optical sensitivity to light and visual neurons.
Ø Sacrifice spatial and temporal resolution to improve visual reliability for the
slower and coarser features of the world.
The Optical Designs of Nocturnal Compound Eyes :
Ø possess superposition compound eyes
Ø optical sensitivity 100-1000 times higher than that of an apposition
compound eye of the same size
Warrant and Dacke, 2011

8. Compound Eyes Of The Nocturnal Bee M. genalis
Warrant, 2016
Facet lenses of its day-active relative
Lasioglossum leucozonium
Light-sensitive rhabdom Facet lenses of the nocturnal bee M. genalis

9. Difference Between Apposition And
Superposition Compound Eyes
Refracting superpositioncompound eyeFocal appositioncompound eye
Thomas et. al., 2018

10. Apposition eye
Superposition
eye
Diurnal
Insects
Nocturnal
Insects
Source: Encyclopedia Brittanica, Inc

11. Nocturnal Color Vision
Hawk moth- Deilephila elpenor
Superposition eyes- 3 different spectral classes- photoreceptors
~ Centred in the UV
~ Violet
~ Green parts of the spectrum
Carpenter bee- Xylocopa tranquebarica
Colour vision- demonstrated- Indian carpenter bee-
Xylocopa tranquebarica- apposition eyes.
Kelber, 2002

12. Scotopic Colour Vision In Nocturnal
Hawkmoth Deilephila elpenor
Kelber and Roth, 2005

13. The Challenge Of Seeing Well In Dim Light
(a) The problem of the visual stimulus itself: photon shot noise
Photoreceptor’s measure of the average rate of photon arrivals comes with a degree of
uncertainty, an uncertainty referred to as ‘photon shot noise’.
(b) The problem of photon detection: physiological noise
• known as ‘dark noise’- degrades visual reliability even further.
• These three sources of noise- photon shot noise, transducer noise and dark noise
severely limit the ability of the visual system to discriminate contrasts in dim light, thus
degrading the reliability of vision.
Warrant, 2016

14. Solutions For Meeting The Challenge
There are two types of adaptations :
1. Optical Adaptations For Increased Sensitivity To Light
(a) Sensitive compound eyes
Compound eyes of nocturnal insects are built to capture as much
light as possible.
(b) Larger facet lenses and photoreceptors
Warrant, 2016

15. Optical Adaptations In The Compound Eyes Of Nocturnal Insects
For Vision In Dim Light
Megalopta genalis Lasioglossum leucozonium
Warrant and
Dacke , 2016

16. 2. Neural Adaptations
• Peripheral neural mechanisms improve visual reliability.
• Wide-field motion sensitive neurons in the optic lobe of the nocturnal hawkmoth
Deilephila elpenor, allows these moths to see at light intensities 100 times dimmer.
• Summation - It improves visual reliability in dim light.
• Types of Summation:
~ Temporal summation
~ Spatial summation
Warrant, 2016

17. Warrant and Dacke, 2011
Temporal summation
Spatial summation

18. A Possible Mechanism For Spatial Summation
In Megalopta’s Eye
Warrant, 2016

19. Possible Neural Substrate For Spatial Summation
In Nocturnal Bees
Warrant, 2016
The horizontal branches
of the first-order l-fibres
connect to a much larger
number of lamina
cartridges, suggesting a
possible role in spatial
summation. L = lamina,
M = medulla.

20. NAVIGATION IN
NOCTURNAL INSECTS

21. Nocturnal Insect Navigators
Australian
Bogong moth
Agrotis infusa
Bull ant,
Myrmecia pyriformis.
Japanese Red sheild bug
Parastrachia japonensis
Sweat bee
Megalopta genalis
Warrant and
Dacke, 2016
Nocturnal Spring migration (B; green arrows) from southern Queensland to the alpine regions of New
South Wales (NSW) and Victoria

22. HOW NOCTURNAL INSECTS NAVIGATE?
1. Celestial cues
Warrant and Dacke, 2011

23. Nocturnal dung beetles detect dim polarized moonlight, to use it as a compass
cue for orientation.
Straight-line navigation in dung beetles
Nocturnal dung beetle, Scarabaeus satyrus Warrant and Dacke, 2016
The electric field (E-vector) component of
a propagating wave of light
celestial polarization patterns at decreasing sun or moon elevations

24. a. Nocturnal homing using path integration
• It is performed with only a tiny fraction of the night sky (and its celestial cues)
visible through the gaps of the forest canopy above.
b. Nocturnal homing using landmarks
• Landmarks specifying a locality, foraging route or the location of the nest.
• Distant and local landmarks- orientation and navigation of nocturnal insects.
2. Terrestrial Landmarks
Warrant and Dacke, 2016

25. A–C: nocturnal homing using canopy cues in the shield bug Parastrachia japonensis
(Hironaka et. al., 2007)

26. Landmark learning in the
nocturnal halictid bee
Megalopta genalis
(Warrant et.al., 2004)

27. Bull ant workers
(Myrmecia pyriformis)
use local visual
landmarks
(Reid et al., 2011)

28. Visual communication in Firefly
Vision, Behaviour and Bioluminescence –
Ø Fireflies produce a chemical reaction inside their bodies that
allows them to light up- called bioluminescence.
Ø The light emitted by the Photinus greeni light organ is
2.5 x 1010 photons /s /cm2 (calculated from Case and Buck
1973)
Ø The intensity of a Photuris flash at a distance of 1m away
from the source is about 3-20 x 10 6 photons /s /cm2
Alber et al., 1982

29. Firefly (Photinus pyralis)
Mechanism of light production in Firefly

30. Ø The presence of three (near-uv, violet and green) receptor types in the compound
eye of the firefly.
Ø Visual sensitivity depends primarily upon the absorption characteristics of the
photopigments present.
Ø The near-UV visual system in the firefly could facilitate orientation of the insect
with respect to open space. (Mazokhin-Porshnyakov 1969; Gogala 1967)
Alber et al., 1982

31. Conclusion
With their highly sensitive visual systems, nocturnal insects have evolved a remarkable capacity to
discriminate colors, orient themselves using faint celestial cues, fly unimpeded through a complicated
habitat, and navigate to and from a nest using learned visual landmarks. Even though the compound
eyes of nocturnal insects are significantly more sensitive to light than those of their closely related
diurnal relatives, their photoreceptors absorb photons at very low rates in dim light, even during
demanding nocturnal visual tasks. To explain this apparent paradox, it is hypothesized that the
necessary bridge between retinal signaling and visual behavior is a neural strategy of spatial and
temporal summation at a higher level in the visual system. Exactly where in the visual system this
summation takes place, and the nature of the neural circuitry that is involved, is currently unknown
but providesa promisingavenue for future research.