title: Four photoreceptor classes in the open rhabdom eye of the red palm weevil, Rynchophorus ferrugineus Olivier.
abstract: The red palm weevil (RPW) is a severe palm pest with high dispersal capability. Its visual sense allows it to navigate long distances and to discriminate among differently colored traps. We investigated the RPW compound eyes with anatomical and electrophysiological methods. The ommatidia are composed of eight photoreceptor cells in an open rhabdom arrangement with six peripheral and two central photoreceptors. The photoreceptor signals are relatively slow and noisy. The majority of recorded photoreceptors have broad spectral sensitivity with a peak in the green, at 536 nm. Three minor classes of photoreceptors have narrower spectral sensitivities with maxima in the UV (366 nm), green (520 nm) and yellow (564 nm). Sensitivity below 350 nm is very low due to filtering by the UV-absorbing cornea. The set of photoreceptors represents the retinal substrate for putative trichromatic color vision.
authors.affiliation: Department of Biology, Biotechnical faculty, University of Ljubljana, Večna pot 111, 1000, Ljubljana, Slovenia.
authors.forename: Marko
authors.initials: M
authors.lastname: Ilić
authors.affiliation: Laboratory of Neuroethology, Department of Evolutionary Studies of Biosystems, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa, 240-0115, Japan.
authors.forename: Primož
authors.initials: P
authors.lastname: Pirih
authors.affiliation: Department of Biology, Biotechnical faculty, University of Ljubljana, Večna pot 111, 1000, Ljubljana, Slovenia. gregor.belusic@bf.uni-lj.si.
authors.forename: Gregor
authors.initials: G
authors.lastname: Belušič
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D055253:Color Vision / Q000502:physiology*; D054910:Compound Eye, Arthropod / Q000033:anatomy & histology*; D015350:Contrast Sensitivity / Q000502:physiology*; D004596:Electroretinography; D008027:Light; D046529:Microscopy, Electron, Transmission; D017956:Photoreceptor Cells, Invertebrate / Q000145:classification* / Q000502:physiology* / Q000648:ultrastructure; D012160:Retina / Q000166:cytology*; D013053:Spectrophotometry; D048889:Weevils / Q000033:anatomy & histology / Q000502:physiology
keywords: Color vision; Compound eye; Photoreceptors; Spectral sensitivity