The Abstract of my PhD-Thesis, Goettingen 1999:

Males of the gomphocerine grasshopper species Stenobothrus rubicundus (GERMAR 1817) produce calling and courtship songs by rubbing their hindlegs against the folded forewings, like other related species. Additionally, they show brief sequences of short sound pulses in these songs. These pulses are made by a step-wise downstroke of the hindlegs, but can equally be obtained by wing movements with the same frequency, while thickened veins of the hindwings touch each other at the upper reversal point. This is called "wing stridulation". This raises the question whether these movements are produced by the stridulation or flight pattern generator. To answer this, intracellular recordings have been made from interneurons of both pattern generators.
The interneurons that are active throughout stridulation belong to 8 known types of neurons already identified in other grasshopper species as being core or premotor parts of the stridulation pattern generator. One new stridulation interneuron (T3-LC-7) could be described. Five of the stridulation interneuron types are rhythmically active during the step-wise downstroke, the other types could not be tested.
All tested interneurons of the flight pattern generator are neither active nor inhibited during normal stridulation but unfortunately could not be examined in the step-wise downstroke. Only one of the tested stridulation interneurons showed EPSPs on wind stimuli or flight activity, all others received tonic inhibition. This neuron showed positive immunoreactivity to GABA.
Most likely the stridulation pattern generator is as a whole tonically inhibited during flight. Destruction of all four tegulae did significantly alter the flight frequency, but had no effect on the production of the step-wise downstroke.
The most likely conclusion of these findings is that the steps are produced by the stridulation pattern generator which alters its normal activity and muscular timing to produce this particular pattern.
(This work has been published at the Cuvillier-Verlag, Goettingen, ISBN  3-89712-547-1, for other publications go to my publications page)



 Back to my Homepage