SONG PATTERN-RECOGNITION AND AN AUDITORY TIME WINDOW IN THE FEMALE BUSH-CRICKET ANCISTRURA-NIGROVITTATA (ORTHOPTERA, PHANEROPTERIDAE)

Mate finding in the phaneropterid bushcricket Ancistrura nigrovittata is achieved by a duet, where the female replies with a short sound to the male song. In experiments with artificial song models we analysed the parameters necessary for eliciting a female response. A verse of t he male song consists of a group of 5-9 syllables which after an inter val of about 400 ms is followed by a final syllable. The female respon se was shown to depend on two processes: (i) recognition of the syllab le group as belonging to a conspecific male and (ii) perception of the final syllable as a trigger. Critical parameters for the recognition process are the duration of syllables and syllable pauses, as well as the number of syllables in a group. However, even with an optimal syll able group, the response probability still depends on the interval bet ween the syllable group and the final syllable. The female only respon ds when the final syllable of the male song occurs within a 250 ms lon g time window beginning approximately 250 ms after the end of the male 's syllable group. Her reply consists of a single tick, which follows the male's final syllable with a latency of only 25 ms.