Flash Communication in Fireflies

The firefly flash is a signal in a courtship system based upon timing patterns controlled by the brain. Courtship flash codes supply both species and sex identification and rely on precise timing and stereotypy of one or a few temporal parameters to preserve information. The flash control system is physiologically complex. It involves random physiological fluctuations that tend to introduce variability into communication and thus to degrade information transfer. To understand the physiological basis of flash communication it is therefore essential to establish the limits of fluctuation within which the entire system must operate. The physiological processes that are so variable involve sensory reception, central integration, and the output of an unusual neuroeffector (the firefly lantern). For example, the pattern generators of fireflies must be primed to operate with sufficient precision. Insufficiently primed animals produce flashes of abnormal kinetics and timing. Flashing behavior of fireflies is greatly affected by the animal's state of arousal; quiescent fireflies are induced to flash with difficulty, whereas excited animals produce rapid and varied luminescent emissions. Also, the firefly's visual apparatus is highly specialized for the reception of fast transient flashes, and its ability to process other types of photic information remains unknown. Finally, and perhaps most significantly, the flash pattern generators of fireflies can be entrained by incoming flashes to produce, in females, responses of appropiate delay; and in males, flash synchrony. Lloyd (1981b) has proposed that aggressive mimicry by Photuris femmes fatales has had a great evolutionary impact on the flash codes of prey firefly species. This mimicry may represent a simple entrainment of Photurius females to a wide array of flash patterns. The precision of flash behavior should be measured in females of known physiological state and previous flash history in order to asses the effect of mimicry on firefly courtship behavior.