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Spectral tuning of bioluminescence emission and visual sensitivity among beetles Abner B. Lall*1; TW Cronin2; AA Carvalho3; EJH Bechara4; JM deSouza3 (1) Dept. of Biology, Howard University, Washington, DC 20059, USA; (2) Department of Biological Science,, University of Maryland Baltimore County, Baltimore, MD 21250, USA; (3) Instituto de Psicologia, Departamento de Psicologia Experimental, Universidade de Sao Paulo, Sao Paulo, SP Brasil; (4) Instituto de Quimica, Departamento de Bioquimica, Universidade de Sao Paulo, Sao Paulo, SP Brasil      *(alall@fac.howard.edu) Optimization of optical signal detection would require that the peaks of species bioluminescence (BL) emission match its visual spectral sensitivity (VSS). Such matching between the BL peaks and the species VSS was observed among ten lampyrids, four elaterids and one phengodid. In situ microspectrophotometric measurements show that vision is mediated by photopigments (P540 to P560) in conjunction with screening pigments whose lambda max varies from 460 to 517 nm. These beetles possess superposition compound eyes adapted for night vision. The presence of unique species-specific screening pigments not only shifts the VSS of the visual receptors into long wavelengths [lambda max 560 (lime-green) to 580 nm (yellow-orange)] but also narrows the ERG VSS among twilight-active firefly species such that the shapes of species VSS and BL match. The species-specific screening pigments act as noise filters to maximize signal-to-noise ratios by absorbing green foliage-reflected sunlight at dusk among twilight-active fireflies and short wavelength space-light at night among night-active beetles which possess broad green ERG VSS. Mutual tuning between BL emission and VSS has been selected for among these beetles. NSF grant # IBN-9724028.  [Talk: lall.abnerb.23131]

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