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
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