Spectral tuning of bioluminescence and visual sensitivity in males of Brazilian firefly species inhabiting dim light environments (Coleoptera: Elateroidea: Lampyridae)

Abstract

Bioluminescence in fireflies is essential for sexual communication, and each species has evolved a specific bioluminescence emission capable of being detected by its visual system. This spectral "tuning" between visual sensitivity and bioluminescent emission has been established in 14 species of North American fireflies inhabiting diverse photoecological niches. Here we extend that research to three Brazilian species. Macrolampis omissa inhabits the Cerrado (savannas), while Photinus sp1 and Pyrogaster moestus are often sympatric species inhabiting borders of mesophyll rain forests and secondary growth. P. moestus particularly favors humid areas of the forest. M. omissa and Photinus sp1 are twilight-active fireflies emitting yellow bioluminescence. P. moestus is a "twi-night" species emitting green bioluminescence.It initiates flashing at the end of twilight and continues activity into the night. The visual spectral sensitivity of dark-adapted compound eyes in these three species is similar, showing a maximum in the yellow-green wavelengths and a secondary peak in the near-UV, suggesting the presence of two receptors. The bioluminescence emission spectrum in each species is tuned to its yellow-green visual sensitivity peak.Green chromatic adaptation experiments on Photinus sp1 and P. moestus suggest the presence of a blue receptor. The presence of near-UV, blue, and long-wavelength receptors in the compound eyes would enable a trichromatic color vision in Brazilian firefly species active in dim illumination.

Inventory and ecological aspects of bioluminescent beetles in the Cerrado ecosystem and its decline around Emas National Park (Brazil)

“…Observations made during 2 November evenings, showed that the adult males of Euryopa clarindae and E. laurae begin to be attracted to light traps around 6:00 PM, when the downwelling sky light is around 5 Lux, the west coming light (sunset) is around 6 Lux and the upwelling grass reflected light is between 0.35 and 0.8 Lux. The orange bioluminescence color and the time of onset of activity of this species is apparently in agreement with the optimization of visual detection of bioluminescence color hypothesis (Lall et al 2009), which predicts that yellow/orange colors contrast better with the green photic background effect of the grass at the twilight. Somehow, orange bioluminescence may have been especially advantageous in the open Cerrado ecosystem.…”

Opsin diversity and evolution in the Elateroidea superfamily: Insights from transcriptome data

“…However, the correlation between the bioluminescence phenomenon, observed among these species, and the sexual mate (colour emission, period activity, and flash pattern) has attracted the attention of the research community (e.g., Buck, 1937; Lall et al, 1982, 2000, 2010; Lloyd, 1979; Martin et al, 2015; Sander & Hall, 2015; Seliger et al, 1964). Physiological studies in Lampyridae and Elateridae in the last decades revealed the presence of absorption wavelength peaks in the UV and green‐yellow spectra, indicating the presence of two photoreceptors (Lall et al, 1988, 2000, 2010, 2023; Seliger et al, 1964). Meanwhile, a few studies at the molecular level explored the opsin diversity in Lampyrdae, suggesting a simple visual system, with a unique copy of LW‐ and UV‐opsin in the species of this family (Martin et al, 2015; Sander & Hall, 2015).…”