Its a nice topic.......which is very interesting to know the life of insect under dark

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2. LOW LIGHT, BAD FLIGHT
VISION AND VISUAL NAVIGATION IN
NOCTURNAL INSECTS
Prashant
PAL 0013
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3. Compound eyes:
Insects recognize and react to conspecifics
 Distinguish and avoid predators
 Locate food sources and intercept prey
 Navigate
 Walk, swim or fly
Nocturnal insects:
Introduction
Light levels can be up to 11 orders of magnitude lower
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4.  Behavioral modifications
 Visual system itself
How?
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5.  Apposition compound eyes
Example: Nocturnal bees and
wasps
Nocturnal compound eyes
 High optical sensitivity- Superposition
compound eyes
Example: Nocturnal moths and beetles
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6. Ommatidia
Hexagonal Circular Dome
Three basic models of the compound eye
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7. Difference

8. Visual processing in nocturnal
insects
Vision
Eyes with an enhanced optical sensitivity to light
Visual neurons that sacrifice spatial and temporal resolution
to improve visual reliability for the slower and coarser
features of the world
EYES AND VISION IN NOCTURNAL INSECTS
Optics
Retina of the compound eye
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9. A superposition eye can have
optical sensitivity 100–1000 times
higher than that of an apposition
compound eye
The Optical Designs of Nocturnal Compound Eyes
A
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10. The ratio of the number of photons absorbed by a photoreceptor
to the number emitted per steradian of solid angle from a unit
area of an extended source
Where,
A-Diameter of eye operture
l - length of the rhabdom
K -peak absorption coefficient
of the visual pigment
 f -focal length of the
ommatidium
 d -diameter of the rhabdom.
Optical sensitivity
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11. Good sensitivity to a spatially extended scene results from
a pupil of large area (π A2/4)
Photoreceptors that each view a large solid angle of visual
space (πd2/4 f 2 steradians)
Absorb a substantial fraction of the incident light (kl/2.3+kl).
This equation predicts
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12. M. genalisA. mellifera
2 μm 8 μmRhabdum width
Facet size 36 μm20 μm
M. genalis an optical sensitivity that is roughly 27 times
greater than that of A. mellifera
Warrant et al., 2004
How nocturnal life has affected the optical structure
and sensitivity?
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13. Warrant et al., 2006
Ocellar optics in nocturnal and diurnal bees and wasps
Nocturnal sweat bee, Megalopta genalis,
Nocturnal paper wasp, Apoica pallens
Diurnal paper wasp, Polistes occidentalis
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14. Megalopta genalis Augochloropsis fuscognatha 14

15. Apoica pallens Polistes occidentalis15

16. Longitudinal light microscope sections of median ocelli
Apoica pallens (A), Megalopta genalis (B),
Polistes occidentalis(C)
l=lens
r=retina
p=screening
pigment
granules
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17. Polistes occidentalis (C).
Megalopta genalis (A)
Apoica pallens (B)
The optical properties of median ocelli
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18. General property of photoreceptors- Bumps
At higher intensities: the bump responses fuse to create a
graded response whose duration and amplitude are
proportional to the duration and amplitude of the light
stimulus
Photoreception and the Reliability of
Vision in Dim Light
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19. At very low light levels: a light stimulus of constant intensity is
coded as a train of bumps
At somewhat higher light levels: the constant intensity is coded
by a graded potential of particular amplitude 19

20.  The major limitation for nocturnal vision in insects
 Arises from the stochastic nature of photon arrival and
absorption
Sources of Visual noise
 Photon shot noise
 Dark noise
 Transducer noise
Visual noise
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21. • Photoreceptor absorbing a number of N photons
experiences an uncertainty (or photon shot noise) of √N
photons
(Land, 1981; Warrant and McIntyre, 1993)
• Decreasing photon catch in dim light results in an
increasing noise level
• As two visual channels need to detect sufficient photons in
order to reduce this noise level
PHOTON SHOT NOISE
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22.  Consists of spontaneous thermal responses in the
absence of photons, which are indistinguishable from
membrane potentials (quantum bumps) produced by photons
(Barlow, 1956)
 These fluctuations are more frequent at higher
temperatures and introduce uncertainty at low light
intensities.
Even though dark noise is much lower in invertebrates than
in vertebrates
Dark noise
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23. Photoreceptors are incapable of producing identical bumps
of fixed amplitude, latency and duration to each (identical)
photon of absorbed light.
This source of noise, originating in the biochemical
processes leading to signal amplification
To maximise the photon catch or signal-to-noise ratio to
enhance sensitivity
Transducer noise
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24.  Photoreceptor responses to single photons (i.e bumps)
are much larger in nocturnal insects
Retinal adaptations for nocturnal
vision
Large bumps have been demonstrated
Nocturnal crane flies
Cockroaches
Bees
Spiders
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25. Quantum bumps of nocturnal M. genalis and diurnal L.
leucozonium 25

26. Contrast gain of the bees M. genalis and L. leucozonium
Fredriksen et al., 200826

27.  A large number of animals are known to use colour to
detect, discriminate and recognise objects
 Food sources
 Mating partners
 Landmarks or their homes
Nocturnal Color Vision
An animal needs to possess and use at least two types of photoreceptors,
with different spectral sensitivities, to look at an object
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28. Simple 4-stage model of colour discrimination with two
spectral types of receptors.
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29. Natural light levels and limits of colour vision 29

30.  UV
 Violet
 Green
Kelber, 2003
Deilephila elpenorMacroglossum stellatarum
Colour Vision in Diurnal and
Nocturnal Hawkmoths
Three different spectral classes of photoreceptors
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31. Schematic drawings of the structure of the rhabdom of
Deilephila elpenor
Schlecht et al., 1978
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32. Color vision in D. elpenor is color-constant
 This moth can not only be trained to associate a sugar
reward with a blue disc at starlight
 Discriminate this blue disk from other discs in various
shades of gray with a choice frequency of at least 80%.
Kelber, 2003
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33. Colour vision in Deilephila elpenor
Kelber et al., 2002
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34. Colour constancy 34

35.  Many nocturnal insects have evolved sufficiently
sensitive visual systems
Celestial cues
Terrestrial visual Cues
Nocturnal Navigation and
Orientation
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36. At night, the brightest and most easily discernable cue in
the sky is undoubtedly the moon
Navigation and orientation using
celestial cues
Its bright disk is used for orientation and navigation in a number of
different nocturnal insects
Ants Earwigs
Moths
Beetles
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37.  A much dimmer and more subtle cue associated with the
moon is its pattern of polarized light.
 This circular pattern, centered around the moon, arises
because of the atmospheric scattering of moonlight as it
travels toward Earth
 Light is most polarized around a circular celestial locus
90◦ from the moon, and the circular pattern of polarized
light moves with the moon
Cont….
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38.  On full moon nights
 On four nights before and after this event
Dacke et al., 2003
Lunar orientation in a beetle
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39. The path taken by a ball-rolling Scarabaeus zambesianus
0 to 90 90 or 180
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40. Circular diagrams of turns made by Scarabaeus zambesianus
rolling under the night sky.
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41.  Visual detection of optic flow is also clearly necessary for
controlling nocturnal flight
Navigation and orientation using
terrestrial cues
 Dim light gypsy moths
 Mosquitoes
 Locust
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42. Landmark orientation in sweat bee
Warrant et al., 2004 42

43.  X. leucothorax is diurnal
 X. tenuiscapa is largely diurnal and
occasionally crepuscular
 X. tranquebarica is truly nocturnal
Somanathan et al., 2008
Flight activity in three species of carpenter bees
in relation to light intensities
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44. Somanathan et al., 2008
Flight activity in all three species as a function of light
intensity
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45. Two-dimensional reconstruction of flight paths of X. tranquebarica
at a nest site 45

46. X. leucothorax X. tenuiscapa
X. tranquebarica
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Scanning electron micrograph of heads

47. Canopy or Individual trees
As the animal moves under the tree canopy, the brighter
sky in the gaps of the canopy, together with the darker
area under the canopy
Ex: Nocturnal shield bug, Parastrachia japonensis
Insects living in forests
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48. Schematic drawing of the displacement test
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49. A nocturnal provisioning path and the distribution of foraging
and homing directions 49

50. Homing path and distribution of homing directions in a
nocturnal displacement test 50

51. Nocturnal homing using canopy cues in the shield bug
Parastrachia japonensis
Hironaka et al., 2008
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52. Reid et al., 2011
Myrmecia pyriformis Smith
Landmark panorama provide night-active bull
ants with compass information during route
following
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53. Landmark-blocking experiment
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54. A) initial orientation of individual ants at the nest the
B) time taken to exit the 30cm circle and
C) the proportion that crossed the 1.2m reference line 54

55. Displacement experiment. 55

56. Neural adaptations
 An increase in the response gain of the
photoreceptors with decreasing light intensity can
further enhance sensitivity but does not improve
photon capture itself
(Laughlin, 1981)
 The ultimate solution to optimise sensitivity at
low light intensities is to process the incoming
visual signal using a strategy of neural summation
in space and time
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57. Temporal Summation
 Visual systems can also improve image reliability
at night by slowing vision down
 Lengthening the eye’s visual integration time at
night
 Signal-to-noise ratio of lower temporal
frequencies is improved
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58.  Temporal summation results in a slower but more reliable
visual world
 Extremely long photoreceptor integration times
 Sit-and-wait predators and slowly moving animals,
temporal summation is certainly a good strategy
Cont…
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59. Theory of spatial summation
Spatial Summation
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60.  Photons are integrated over wider visual fields,
which is similar to a widening of the angular
sensitivity function
 Only when neural summation is matched to the
extent of the visual overlap present in the eye
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61. Warrant, 2004
A Possible Mechanism for Spatial Summation in Megalopta’s Eye
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62. Greiner et al., 2004 and Ribi, 1975
Comparison of the First-Order Interneurons, L-fiber types L3
and L4, of the M. genalis female (left) and the worker
honeybee A. mellifera (right)
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63.  Nocturnal insects have excellent night vision
 With the capacity to discriminate colors
 Orient themselves using faint celestial cues fly unimpeded
through a complicated habitat
 Navigate to and from a nest using learned visual
landmarks
Conclusion
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64.  The photoreceptors of nocturnal insects respond more
slowly and have a higher contrast gain
 A neural strategy of spatial and temporal summation at a
higher level in the visual system is hypothesized as the
necessary bridge between retinal signaling and
visual behavior.
Cont…
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