Action spectra for the initiation of bioluminescent flashing activity in males of twilight-active firefly Photinus scintillans (Coleoptera: Lampyridae)

Abstract

The action spectra [ S(λ)-functions] for the initiation of bioluminescent flashing were determined in males of twilight-active firefly Photinus scintillans, using horizontal and vertical beams of spectral lights to simulate closed and open space in nature, respectively. The peak of the S(λ)-function in the horizontal beams was in the long (yellow, Fig. 3) and that for the vertical in the short (near-u.v. and blue, Fig. 5) wavelength region. It is concluded that both short and long wavelength visual receptors mediate the initiation of flashing behavior in males of those fireflies which restrict their flashing to twilight-hours. Furthermore under dim illumination conditions as in a closed space, the long wavelength receptor dominate the behavioral response, while in an open space with bright illumination conditions, the short wavelength receptors dominate.