Spectral sensitivity in the compound eye of Rhodnius prolixus (Hemiptera: Triatominae): Electrophysiological responses
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1
Universidad de los Andes, Biological Sciences Department, Colombia
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2
Universidad de los Andes, Physics Department, Colombia
Rhodnius prolixus (Rp) is an important vector of Trypanosoma cruzi, the etiological agent of Chagas disease in Latin America. Rp compounds eyes and ocelli are involved in behaviours such as negative phototaxis and flight dispersion from sylvatic environments to human dwellings. Even though, it is well known that artificial lights are a source of attraction in Rhodnius, it is still not clear if the compound eyes are using a chromatic or achromatic mechanism during active dispersion. In order to bring new information of the mechanism during this behaviour we applied electroretinograms (ERG) to determine the spectral sensitivity of its compound eyes.
Experiments were carried out with 57 adults (males and females) from laboratory rearing and sylvatic foci. Spectral sensitivity was evaluated under three different adaptation conditions: dark, blue and yellow lights. Monochromatic flashes of 300 ms were used as stimuli. 36 wavelenghts in 10 nm steps ranging from 350 to 700 nm at a constant intensity of 3,4 microwatts per square centimeter were tested in all adaptation conditions. Controls blocking light beams or allowance of a shutter opening without light stimulus were also carried out before all experiments.
Results showed maximal responses in the ERG after 70 min of dark adaptation. Insects adapted to yellow lights showed one peak of spectral sensitivity at 470-490 nm, while insects adapted to dark and blue lights showed one further peak at 520-550 nm. The two maximum sensitivity peaks were found in sylvatic and laboratory rearing insects and in males and females as well.
Electrophysiological evidence obtained with the ERG showed the presence of only two peaks of spectral sensitivity in the compound eyes of Rp. The presence and interaction of these two photoreceptors in the eyes can be related to a chromatic mechanism suggesting color vision to detect artificial light sources with a wide range of spectral components.
Acknowledgements
Financial support: Colciencias Project 1204-459-21479.
Keywords:
Aposition compound eye,
Electroretinogram,
Triatominae
Conference:
Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012.
Presentation Type:
Poster (but consider for participant symposium and student poster award)
Topic:
Sensory: Vision
Citation:
Hincapie Peñaloza
EA,
Guzmán
DA and
Molina
J
(2012). Spectral sensitivity in the compound eye of Rhodnius prolixus (Hemiptera: Triatominae): Electrophysiological responses.
Conference Abstract:
Tenth International Congress of Neuroethology.
doi: 10.3389/conf.fnbeh.2012.27.00437
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Received:
10 May 2012;
Published Online:
07 Jul 2012.
*
Correspondence:
Mr. Eduwin A Hincapie Peñaloza, Universidad de los Andes, Biological Sciences Department, Bogotá, Colombia, ea.hincapie34@uniandes.edu.co