CHOLINERGIC ACTIVATION OF STRIDULATORY BEHAVIOR IN THE GRASSHOPPER OMOCESTUS-VIRIDULUS (L)

When acetylcholine (ACh) and its agonists are injected into neuropile regions of the protocerebrum and the suboesophageal ganglion of male a nd female grasshoppers of the species Omocestus viridulus (L.), they e licit stridulation in a pattern no different from that of natural song . Stridulation can even be evoked in mated females which normally do n ot sing. By choosing suitable ACh agonists, nicotinic and muscarinic A Ch receptors can be activated selectively. Activation of nicotinic ACh receptors produces individual song sequences with rapid onset; the st ridulation induced by activation of the muscarinic ACh receptors begin s after a longer latency, increases slowly in intensity and is maintai ned for many minutes. The sites within the cephalic ganglia where song can be initiated pharmacologically coincide with regions in which des cending stridulatory command neurones arborize.