In this master thesis we compared the response of filiform sensilla of the firebug Pyrrhocoris apterus to airflow with different temporal and spatial properties. We measured the amplitude, speed and phase shift of the sensory hair deflection and physiological response (the firing of action potentials) of T1 and T2 sensilla at different amplitudes, frequencies and directions of sinusoidal airflow. We also measured their response to airflow produced by flapping wings of flies, which are potential heteropteran parasites. The T1 sensillum is significantly more sensitive to the sinusoidal air current than the T2 sensillum. Different sensitivity enables a wider dynamic range of the entire system. Changes in the direction of the airflow had an effect on the phase shift of the sensory hair and the phase and amplitude of the physiological response. Significant differences were observed between the sensilla on the source-side of airflow and the contralateral sensilla, minor differences were observed between the ipsilateral sensilla. The directional dependence of the response, despite the small number of sensilla, enables rough coding of stimulus direction. Both types of sensilla respond to the fly at a distance of more than 10 cm. They respond to the low-frequency currents and the oscillations of the air particles with wing beat frequency. The contralateral T1 sensilla respond to wing beat frequency with synchronous firing of action potentials. The firebug can therefore detect potential predators/parasites such as fly, and perhaps based on synchronous firing of action potentials even recognize them.
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