....“We have been studying Leptophyes punctatissima for many years, mostly the acoustic biology.
The animal communicates using ultrasound at 40 OOO Hz* and so is inaudible to humans. Communication between males and females in one of the fastest interchanges in the insect world, being complete in as little as 25 thousandths of a second.
Such short ultrasonic signals are likely to be scattered substantially by vegetation in the environment and we have been looking at the types of habitat occupied by these animals. In doing so we discovered that the animals have food preferences – the young stages at the Warren in Folkestone feed on sage, which is not present at the site in Germany. Leptophyes is flightless, so the UK population is derived from those individuals who followed the retreat of the ice northwards at the start of the present inter-glacial period and arrived before the English Channel formed.”.........
Dr David J Robinson FRES – Dept of Biological sciences, Open University
Dr Patricia J Ash – Oxford Regional Centre, Open University
Dr Marion, J Hall – HSW, Open University
Prof Jurgen Rheinlaender – Nordkirchen, Germany
http://www.northmoortrust.co.uk/home/research/speckledbushcricket
"The ability of the bushcricket Leptophyes punctatissima to orient to elevated sound sources was investigated. Males were placed on a walking compensator and oriented in response to a synthetic female reply, which was broadcast via one of five loudspeakers placed at elevations of 0°, 30°, 60°, 75° and 90°. Forward and backward movements were compensated, so that males remained at the same distance and elevation to the sound source. With increasing loudspeaker elevation, the males meandered more, and the ratio of the ideal path length to the actual path length decreased. The same was true for the correlation between stimulus angle and turn angle, and there were more turns to the wrong side with increasing loudspeaker elevation. Most males performed phonotaxis with a high acuity up to an elevation of 60°. Individuals varied strongly in their performance especially at a source elevation of 75°, where some were still very accurate in their approach, whereas the acuity of others decreased rapidly. We also describe a behaviour where males tilt their body axis to more anterior and sideward positions, both during walking and while calling on the spot. This behaviour is interpreted as a kind of directional scanning in order to actively induce changes in binaural cues."
http://www.springerlink.com/content/j653xk723uwg5327/
*L'oreille humaine commence à percevoir les sons à partir de 20 hertz (c'est-à-dire 20 cycles par seconde). En dessous, il s'agit d'infra-sons, inaudibles,
L'oreille entend les sons jusqu'à 20 000 hertz mais pas au-dessus alors que les animaux les perçoivent.
