CONTROL OF FLASHING IN FIREFLIES. I. THE LANTERN AS A NEUROEFFECTOR ORGAN

Abstract

Oscilloscope records are presented of normal spontaneous flashes and of flashes induced by a variety of electrical stimuli at a variety of anatomical sites in several species of lampyrid firefly. Flashes of adults have long response latencies (25 to 250 msec. at 25[degree]C in different species) and durations (100 to 1000 msec.) and can be repeated many hundred times with only slight fatigue. The response shows strength-duration relations, long-lasting facilitation, and frequency responses (summation, treppe, tetany) which are strikingly similar to those of more conventional neuroeffector systems. Latency lengthens with falling temperature, Q10 values for the 10[degree]-30[degree] range varying from about 2.4 to 1.4. Extreme temperatures slow the decay phase of luminescence preferentially, as does hypoxia. The flashes of most species differ characteristically in time course, response latency and other electrophysiological properties. The responses of Photuris larva are roughly similar to those of the adult, but 10 times slower. The time course of light intensity change during flashes induced under various conditions, and long-lasting glows, are discussed in possible relation to underlying excitation and effector mechanisms.