1. Neuroethology: Sound in insects http://biolpc22.york.ac.uk/404/

2. References nYoung, D (1989) Nerve cells and animal behaviour CUP [1st edition, chapter 7] nAlso, chapters in: u Carew Behavioral neurobiology u Zupanc Behavioral neurobiology npapers are on the web http://biolpc22.york.ac.uk/404/cjhe/ cricket_singing/insect.htm

3. What is neuroethology? napproach to analyse neural function in terms of evolutionary advantage

4. Main points of lecture nSound transmission is inefficient nInsects use sound in a major way nOvercoming physical obstacles nModifying u wings for sound production u the environment for sound production u cuticle to hear nPrivate communication

5. About sound nsound is a wave of particle compression and rarefaction    nenergy (or power) is transferred from sender to hearer nsound gets quieter further away nsound has to be discriminated according to species, context and from random noise

6. Sound properties nspeed c (330 m s -1 ) wavelength  (m) nfrequency f (Hz, cycles/s) nfor 330Hz, wavelength 1m nfor 3.3kHz, wavelength 0.1m nfor 33kHz, wavelength 0.01m = 10mm

7. Power transfer - i nFirst problem for an insect - nfor air/water interface about 0.02%

8. Power transfer - ii nUsually other insect far away - nWith distance, power decreases nmore bad news for insects!

9. Power transfer - iii nUsually insects small - nsound emitted is dependent on ratio of insect size / wavelength of sound

10. Power transfer - iv if you are smaller than 0.2 * more bad news!

11. Insects use sound in a major way nMantids* nGrasshoppers/crickets* nbugs* nbeetles* ndiptera (true flies)* nlacewings nmoths How do they manage this if physics is so unfavourable?

12. Overcoming physical obstacles nResonance nBaffle nHorn nSound production nSound reception

13. Resonance nMass and a spring; resonant frequency ns is stiffness, m mass nbelow f o in phase; at f o 90o; above f o out of phase

14. Gryllus nField cricket nnice loud song, carries a long way nattracts females & males nterritorial

15. Gryllus EMGs sound oscillogram sonogram

16. Females…

17. … walk to the loudest sound

18. n Sound made by wing plectrum

19. add wax to harp nfrequency reduced nresonator affected

20. remove teeth

21. Gryllus campestris sound output 60  W nmuscle work 2 mW nefficiency 3% Can they do any better?

22. Bush crickets nHigher frequency ndamped oscillation

23. Baffle nBush cricket u Oecanthus u power * 12

24. Gryllotalpa nmole cricket

25. Horn shaped burrow

26. Gryllotalpa nsound output 1 mW nmuscle work 5 mW nefficiency 20%

27. Summary so far nModified wings for sound production nModifying the environment for sound production Well done the male crickets! Now onto: what about hearing?

28. Hearing nlocust = grasshopper ears

29. Tympanum structure

30. nMuller’s organ has sensory endings in it nTympanum (ear drum) taut membrane side view top view

31. Movement it’s the relative movement which will stretch the axons

32. Movement npeaks at 3 & 6kHz indicate resonance nresonance also shown by phase plot nfolded body not in phase with membrane u even when at 4kHz amplitude is same nrelative movement needed to stretch axons of Muller’s organ

33. Cricket hearing nacoustic trachea nacts like horn for 5kHz sound

34. Summary so far: Resonance!! nModified wings for sound production nModifying the environment for sound production nModified cuticle to hear Now onto: shh, let’ keep this to ourselves?

35. Drosophila courtship nMale has black tip nOlfaction nSinging

36. Detecting vibration nnear field sound u movement detector u aristae - bristles on antennae

37. Private communication nSound movement in dB nsince sound is measured on a log scale, 80 << 95

38. Summary nThe neuroethological approach relates the function of the nervous system to its evolutionary advantage nMany insects use sound nproduce it quite efficiently nhear it effectively