Bioluminescence emissions of female fireflies of the species Luciola praeusta

Abstract

Numerous investigations have been carried out on bioluminescence emissions from male fireflies. However, very few observations have been made on the emitted light from female specimens. Even in those, apart from observing responses from females to courtship flashes from conspecific males, detailed studies have not been performed. Here we present a first report on the light of female fireflies of the Indian species Luciola praeusta Kiesenwetter 1874 (Coleoptera:Lampyridae:Luciolinae). In the steady-state emission spectrum over the temperature range of 20–40°C, the peak wavelength is the same as, while the full width at half maximum is larger than, that of a male specimen of this species. Increase in temperature up to 45°C brings out a change in both the peak and FWHM values, shifting towards red. In the time-resolved measurement, duration of a flash, which is noticeably larger than that of a male, is found to decrease exponentially with temperature at 20–40°C. Further increase in the temperature produces a minimum flash duration at 41.5°C, and beyond this causes a considerable increase in duration for small increase in temperature. Additionally, lowering the temperature below 20°C makes a single flash appear as a combination of two or three flashes.