EFFECTS OF NEURAL ACTIVITY ON THE FIREFLY PSEUDOFLASH

¹ Division of Biology, State University of New York Long Island Center, Oyster Bay, New York

1. Hypoxic glows and pseudoflashes were studied in adults of the lampyrid fireflies, Photinus pyralis Linn. and Photuris sp.

2. In spontaneously flashing Photinus adults a large number of successive pseudoflashes of high intensity can be induced. Induction of pseudoflashes in quiescent animals results in decline of successive pseudoflash and hypoxic glow intensities, and increase in the time required not only for hypoxic glow onset but also for development of maximal hypoxic glow intensity.

3. Electrical stimulation during hypoxia increases the rate of hypoxic glow rise, commonly by recruiting new luminescing areas within the lantern, and can maintain the hypoxic glow beyond the normal period. Electrical stimulation when continued during readmission of air superimposes flashes on the pseudoflash decay phase only.

4. Perfusion of the body cavity with 10^-4 M eserine enhances the ability to induce high intensity pseudoflashes and hypoxic glows.

5. Transection of the nerves supplying the seventh abdominal segment reduces the ability of that segment to produce pseudoflashes, while pseudoflashes can be obtained from that portion of the lantern occupying the sixth segment. Electrical stimulation of the seventh segment after nerve transection can partially restore its pseudoflash capability.

6. No nerve impulses were observed during the hypoxic interval immediately prior to and during induction of the pseudoflash although neural bursts and their associated flashes were noted before and after hypoxia and during its early period.

7. The observations implicate the innervation in the pseudoflash. A possibility suggested is that previous neural activity serves as a priming mechanism by mediating the removal of a chemical inhibitor.

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