A look into the invisible ultraviolet - B sensitivity in an insect [Caliothrips phaseoli] revealed through a behavioural action spectrum

Caliothrips phaseoli, a phytophagous insect, detects and responds to solar ultraviolet-B radiation [UV-B; lambda less than or equal to 315 nm] under field conditions. A highly specific mechanism must be present in the thrips visual system in order to detect this narrow band of solar radiation, which is at least 30 times less abundant than the UV-A [315-400 nm], to which many insects are sensitive. We constructed an action spectrum of thrips responses to light by studying their behavioural reactions to monochromatic irradiation under confinement conditions. Thrips were maximally sensitive to wavelengths between 290 and 330 nm; human-visible wavelengths [lambda greater than or equal to 400 nm] failed to elicit any response. All but six ommatidia of the thrips compound eye were highly fluorescent when exposed to UV-A of wavelengths longer than 330 nm. We hypothesized that the fluorescent compound acts as an internal filter, preventing radiation with lambda is greater than 330 nm from reaching the photoreceptor cells. Calculations based on the putative filter transmittance and a visual pigment template of lambdamax =360 nm produced a sensitivity spectrum that was strikingly similar to the action spectrum of UV-induced behavioural response. These results suggest that specific UV-B vision in thrips is achieved by a standard UV-A photoreceptor and a sharp cut-off internal filter that blocks longer UV wavelengths in the majority of the ommatidia.

Bibliographic Details

Main Authors:	., Mazza, Carlos, Izaguirre, Miriam Mercedes, Curiale, Javier, Ballaré, Carlos Luis
Format:	Texto biblioteca
Language:	eng
Subjects:	INSECT BEHAVIOUR, INSECT VISION, UV-B, BEHAVIORAL RESPONSE, HYPOTHESIS TESTING, PHOTORECEPTION, PHYSIOLOGY, PIGMENT, SOLAR RADIATION, THRIPS, ULTRAVIOLET B RADIATION, VISION, WAVELENGTH, ANIMAL BEHAVIOR, RADIATION DOSE, RADIATION EXPOSURE, RADIATION RESPONSE, SUNLIGHT, ULTRAVIOLET RADIATION, ANIMALS, BEHAVIOR, ANIMAL, DOSE-RESPONSE RELATIONSHIP, RADIATION, HUMANS, INSECTS, RADIATION DOSAGE, VISION, OCULAR, CALIOTHRIPS PHASEOLI, HEXAPODA,
Online Access:	http://ceiba.agro.uba.ar/cgi-bin/koha/opac-detail.pl?biblionumber=46558
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