Light from a firefly at temperatures considerably higher and lower than normal.

Bioluminescence emissions from a few species of fireflies have been studied at different temperatures. Variations in the flash-duration have been observed and interesting conclusions drawn in those studies. Here we investigate steady-state and pulsed emissions from male specimens of the Indian species Sclerotia substriata at temperatures considerably higher and lower than the ones at which they normally flash. When the temperature is raised to 34 °C, the peak wavelength gets red-shifted and the emitted pulses become the narrowest which broaden considerably thereafter for small increases in temperature; this probably indicates denaturation of the enzyme luciferase catalyzing the light-producing reaction. When the temperature is decreased to the region of 10.5-9 °C, the peak gets blue-shifted and the flash-duration increased abnormally with large fluctuation; this possibly implies cold denaturation of the luciferase. We conclude that the first or hot effect is very likely to be the reason of the species being dark-active on hot days, and the second or cold one is the probable reason for its disappearance at the onset of the winter. Our study makes the inference that these two happenings determine the temperature-tolerance, which plays a major role in the selection of the habitat for the firefly.

Bioluminescence emissions from the Indian winter species of firefly Diaphanes sp.

Numerous studies have been carried out on different aspects of the light from summer-active fireflies. Characteristics of this light have led to very interesting conclusions on the chemiluminescence reaction as well as on the nature of the light from live fireflies. Here we present a first report on bioluminescence emissions from a newly found winter-active Indian species of firefly Diaphanes sp. The steady-state emission spectrum from this species comes out to be apparently similar to those from the other two Indian summer species, Luciola praeusta and Asymmetricata circumdata: asymmetric in nature with a little bit of change in the position of the peak wavelength and in the width of the full width at half maximum. An increase in temperature to approximately 28°C causes a red-shift in the peak wavelength, which probably indicates denaturation of the enzyme luciferase in the live, flashing condition. Emissions in the time domain reveal that the light is never completely off - it decreases in intensity to a low value, sometimes very close to zero, and then increases - a characteristic unheard-of till date. Flash durations are considerably longer than those from the two Indian summer species; those become shorter at about 28°C and increase to noticeably larger values at higher temperatures.

Bioluminescence emissions of female fireflies of the species Luciola praeusta.

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.

In vivo bioluminescence emissions of the firefly Luciola praeusta at low temperatures.

Dependences of light emission from fireflies on external factors like temperature and magnetic field have been studied in recent times. Interesting conclusions have been drawn and hypotheses put forward in those studies. Here we report steady-state and time-resolved emissions of the Indian species of the firefly Luciola praeusta Kiesenwetter 1874 (Coleoptera: Lampyridae: Luciolinae) at temperatures below 20°C. Intensity profiles of emission spectra remain the same as those recorded at normal or high temperatures. Two-flash combinations are frequently formed, giving the appearance of the resolution of a simple flash into two. Simple flashes also become abnormally broad with no uniformity in the increase of their durations. The flashes obtained from fireflies at low temperatures are compared and contrasted with the ones under a strong static magnetic field.