The dynamics of light adaptation in Ascalaphus (Libelloides macaronius; Neuroptera)


  • Andrej Meglič
  • Aleš Škorjanc
  • Gregor Zupančič



Ascalaphus, Libelloides macaronius, owl-fly, light adaptation, pigment migration, eye glow, light intensity dependence, temperature dependence


The owl-fl y or Ascalaphus (Libelloides macaronius; Neuroptera) is an insect with a UV-sensitive superposition eye. Although optical superposition is mainly a feature of dusk/dark active animals, this is a predator living and hunting in bright sunlight. In such conditions the process of light adaptation is believed to be very important, yet it has so far only been partially explored in the owl-fly. Here we present physiological evidence for the migration of the screening pigment, which functions as a light control mechanism. The process of light adaptation was studied optically by dynamic imaging and optical refl ection spectroscopy of the eye-glow. We
established that the eye-glow is reduced uniformly upon illumination and that its diameter doesn’t get smaller, which is indicative of pigment migration in the primary pigment cells. The change in spectral absorbance of the dorso-frontal eye is very similar to the absorbance spectrum of the primary pigment cell screening pigment. We found that the change in the light screening due to
adaptation is rather small – no more than 10 fold for a 10000 fold change in light intensity. We also found that the rate of adaptation is light-sensitive. We propose that a signifi cant part of this light sensitivity is due to indirect heating of the eye and to the very steep temperature dependency of the rate of adaptation between 30 and 35°C.


BENTROP J., SCHILLO M., GERDON G., DRAŠLAR K. & R. PAULSEN 2001: UV-light-dependent binding of a visual arrestin 1 isoform to photoreceptor membranes in a neuropteran (Ascalaphus) compound eye. Febs. Lett. 493: 112–116. DOI:

DRAŠLAR K (1997: Screening pigment distribution in outer segment of Ascalaphus macaronius, eye and its function in dark-light adaptation. – In: REČNIK A., ČEH M. & G. DRAŽIĆ (eds.): 3rd Multinational Congress on Electron Microscopy. »Jožef Stefan« Institute, Ceramics Department,

Portorož, Slovenia, pp. 127–128.

DRAŠLAR K. & U. WOLFRUM 2005a: Structure supporting the light adaptation mechanisms in the dorsal and the ventral eye of Ascalaphus macaronius. – In: ČEH M., DRAŽIĆ G. & S. FIDLER (eds.) 7th Multinational Congress on Microscopy, June 26–30, 2005, Proceedings. Slovene Society for Microscopy: Department for Nanostructured Materials, »Jožef Stefan« Institute, Portorož, Slovenia.

DRAŠLAR K. & U. WOLFRUM 2005b: Structures and mechanisms of light adaptation in the dorsal and the ventral eye of Ascalaphus macaronius. – In: ZIMMERMANN H & K. KRIEGELSTEIN (eds.): 30th Göttingen Neurobiology conference and 6th Meeting of the German Neurobiology Conference. Spektrum Verlag, Göttingen, pp. 146A. GOGALA M., HAMDORF K. & J. SCHWEMER 1970: UV-visual pigment in insects. Z. Vergl. Physiol. 70: 410–413. DOI:

GRIBAKIN F., ALEKSEYEV E., SHUKOLYUKOV S. & M. GOGALA 1995: Unconventional ultraviolet sensitivity spectra of Ascalaphus (Insecta, Neuroptera). J. Comp. Physiol. A. 177: 201–206. DOI:

HAMDORF K. & M. GOGALA 1973: Photoregeneration and sensitivity control in UV Photoreceptors. J. Comp. Physiol. 86: 231–245. DOI:

HAMDORF K., SCHWEMER J. & M. GOGALA 1971: Insect visual pigment sensitive to ultraviolet light. Nature 231: 458–459. DOI:

JENKO K. 2007: Age dependent changes of respiratory chain response dynamics induced by physiological loads to the eye of a blowfly (Calliphora vicina); graduation thesis. Biotechnical Faculty,

Department of Biology, University of Ljubljana, Ljubljana. pp. 1–71.

NILSSON D.E., HAMDORF K. & G. HOGLUND 1992: Localization of the pupil trigger in insect superposition eyes. J. Comp. Physiol. A. 170: 217–226. DOI:

SCHNEIDER L., GOGALA M., DRAŠLAR K., LANGER H. & P. SCHLECHT 1978: Structure of ommatidia and properties of screening Pigments in compound eyes of Ascalaphus (Insecta, Neuroptera). Cytobiologie 16: 274–307.

SCHWEMER J., GOGALA M. & K. HAMDORF 1971: Ultraviolet Visual Pigment – Photochemistry in-Vitro and in-Vivo. Z. Vergl. Physiol. 75: 174–188. DOI:

STAVENGA D.G. 1995: Insect retinal pigments: Spectral characteristics and physiological functions. Prog. Retin. Eye. Res. 15: 231–259. DOI:

STUŠEK P., BELUŠIČ G., ZUPANČIČ G. & K. DRAŠLAR 2005: The dynamical and spectral characteristics of pupillary response in the owlfly Ascalaphus macaronius. – In: ZIMMERMANN H & K. KRIEGELSTEIN (eds.): 30th Göttingen Neurobiology conference and 6th Meeting of the German Neurobiology Conference. Spektrum Verlag, Göttingen, pp. 147A.

STUŠEK P. & K. HAMDORF 1999: Properties of pupil mechanisms in owlfly Ascalaphus macaronius (Neuroptera). J. Comp. Physiol. A. 184: 99–106. DOI:

WARRANT E.J. & P.D. MCINTYRE 1996: The visual ecology of pupillary action in superposition eyes. J. Comp. Physiol. A. 178: 75–90. DOI:

WOLFRUM U., BELUŠIČ G. & K. DRAŠLAR 2003: Structures supporting light – dark adaptation in the compound eye of Ascalaphus (Libelloides macaronius). – In: ELSNER N. & H. ZIMMERMANN ( eds.): 29th Göttingen Neurobiology Conference and the 5th Meeting of the German Neuroscience Society. Georg Thieme Verlag, Göttingen, pp. 541.

ZUPANČIČ G. 2003: A method for dynamic spectrophotometric measurements in vivo using principal component analysis-based spectral deconvolution. Pfl üg. Arch. Eur. J. Phy. 447: 109–119. DOI:

ZUPANČIČ G. & D. PEROVŠEK 2007: Metabolic stress is not likely to be a signifi cant contributor to physiological TRP channel activation in blowfly photoreceptors. – In: Life Sciences 2007: a joint meeting of the Biochemical society, the British pharmacological society and the Physiological society, 9–12 July 2007. Biochemical society, British pharmacological society, Physiological society, Glasgow, pp. 137P–138P.






Original Research Paper

How to Cite

Meglič, A., Škorjanc, A., & Zupančič, G. (2007). The dynamics of light adaptation in Ascalaphus (Libelloides macaronius; Neuroptera). Acta Biologica Slovenica, 50(2), 71-84.

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