FLASH CONTROL AND FEMALE DIALOG REPERTORY IN THE FIREFLYPHOTINUS GREENI

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Abstract
In the Photinus greeni courtship dialog the male emits flashes in pairs (S1S2) about 1250 ms apart at 25.degree., the pairs recurring every 5 to 7 s. The female answers with one flash, usually about 750 ms after the male''s S2 signal (S2R response). S2R latency includes 400 + ms of central nervous delay. Using paired signals of electric light, female responsivity to stimulation at different frequencies was established and excitatory state modified so that S1Rs (responses to the first flash of signal pairs) and spontaneous flashing, became more frequent. S1Rs have a long latency than S2Rs. Flash timing was examined for presumed neural noise, statistical and individual variations, persistence, response cycling, hyperexcitation, fatigue, and habituation. A model central neural flash-control mechanism, based on an excitability transient rising from a resting level to a flash-triggering level, distinguishes S1R from S2R and accounts for much behavioral timing. The female clearly has an input-timing element, used normally for identifying the male''s signal pair. Since females sometimes emit pairs of spontaneous flashes at about the same average interflash interval as the male''s, it is suggested that her timer may, under stress, assume the output-timing role normal in the (genetically nearly identical) male.