Functional properties of trichobothria in the bugPyrrhocoris apterus (L.)

Abstract

1. The trichobothria on the abdomen of the bugPyrrhocoris apterus differ in the length of their sensory hairs and in their functional properties. Three types may be distinguished. On segment four they have the following properties: 2. The sensory hair of type 1 is about 380 μm long. The receptor cell is spontaneously active. The spike frequency increases by deflection in caudal direction and decreases by deflection in the cranial direction. The adaptation is of the phasictonic type, and there is no significant change in sensitivity with prolonged stimulation. This receptor can follow sine stimuli synchronously up to about 160 Hz. 3. Type 2 (sensory hair about 180 μm) has no spontaneous activity. The spike frequency is increased by deflections in cranial and caudal direction. The response is of the phasic-tonic type and phase-locked to the sine wave up to 80 Hz. 4. The response of type 3 (sensory hair about 80 μm) is of the phasic type, and the adaptation is prompt. Like type 2 receptor is excited by deflections in either direction, and it follows sine waves synchronously up to 80 Hz.