Transcript sound07
Neuroethology:
Sound in insects
http://biolpc22.york.ac.uk/404/
References
Young, D (1989) Nerve cells and animal
behaviour CUP [1st edition, chapter 7]
Also, chapters in:
Carew
Behavioral neurobiology
Zupanc Behavioral neurobiology
papers are on the web
http://biolpc22.york.ac.uk/404/cjhe/
cricket_singing/insect.htm
What is neuroethology?
approach to analyse neural function in terms
of evolutionary advantage
Main points of lecture
Sound transmission is inefficient
Insects use sound in a major way
Overcoming physical obstacles
Modifying
wings
for sound production
the environment for sound production
cuticle to hear
Private communication
About sound
sound is a wave of particle compression and
rarefaction
energy (or power) is transferred from sender
to hearer
sound gets quieter further away
sound has to be discriminated according to
species, context and from random noise
Sound properties
c f l
speed c (330 m s-1)
wavelength l (m)
frequency f (Hz, cycles/s)
for 330Hz, wavelength 1m
for 3.3kHz, wavelength 0.1m
for 33kHz, wavelength 0.01m = 10mm
Power transfer - i
First problem for an insect for air/water interface about 0.02%
Power transfer - ii
Usually other insect far away With distance, power decreases
more bad news for insects!
1
2
d
Power transfer - iii
Usually insects small sound emitted is dependent on
ratio of insect size / wavelength
of sound
Power transfer - iv
if you are smaller than 0.2 * l more bad news!
Insects use sound in a
major way
Mantids*
Grasshoppers/crickets*
bugs*
beetles*
diptera (true flies)*
lacewings
moths
Overcoming physical
obstacles
Resonance
Baffle
Horn
Sound production
Sound reception
Resonance
Mass and a spring; resonant frequency
1
fo
2
s
m
s is stiffness, m mass
below fo in phase; at fo 90o; above fo out of
phase
Gryllus
Field cricket
nice loud song,
carries a long
way
attracts females
& males
territorial
Gryllus
EMGs
sound
sonogram
oscillogram
Females…
… walk to the loudest sound
Sound made by
wing
plectrum
add wax to harp
frequency reduced
resonator affected
remove teeth
Gryllus campestris
sound output 60 mW
muscle work 2 mW
efficiency 3%
Bush crickets
Higher frequency
damped oscillation
Baffle
Bush cricket
Oecanthus
power
* 12
Gryllotalpa
mole cricket
Horn shaped burrow
Gryllotalpa
sound output 1 mW
muscle work 5 mW
efficiency 20%
Summary so far
Modified wings for sound production
Modifying the environment for sound
production
Hearing
locust = grasshopper ears
Tympanum structure
Tympanum structure
side view
Muller’s organ
has sensory
endings in it
Tympanum (ear
drum) taut
membrane
top view
Movement
it’s the relative movement which will stretch the axons
Movement
peaks at 3 & 6kHz indicate resonance
resonance also shown by phase plot
folded body not in phase with membrane
even
when at 4kHz amplitude is same
relative movement needed to stretch axons of
Muller’s organ
Cricket hearing
acoustic trachea
acts like horn for 5kHz sound
Summary so far
Modified wings for sound production
Modifying the environment for sound
production
Modified cuticle to hear
Drosophila courtship
Male has black tip
Olfaction
Singing
Detecting vibration
near field sound
movement detector
aristae - bristles on
antennae
Private communication
Sound movement in
dB
since sound is
measured on a log
scale, 80 << 95
Summary
The neuroethological approach relates the
function of the nervous system to its
evolutionary advantage
Many insects use sound
produce it quite efficiently
hear it effectively