1979 Volume 54 Issue 5 Pages 345-357
Adult flies of a bw; st ss strain exhibited an anomalous response (jumping behaviour) to light at the moment the light was intercepted by a hand or the light being turned off. We named the response pyokori (a Japanese word for a jumping in surprise). On the other hand, a Hikone-H wild strain did not show such a response. The pyokori behaviour is determined by a recessive gene(s) located on the second and the third chromosomes. It is necessary that, in order to show the pyokori response, flies must be homozygous for a gene(s) located on the second chromosome and minor gene(s) on the third. The degree of pyokori response was markedly influenced by the intensity of illumination, the wavelength of light, and the age of flies used. After emergence, the flies kept in dark (0 lux) or under high intensity illumination (3000 lux) showed almost no pyokori response. On the other hand, newly emerged flies kept under a low light (50 lux or 100 lux) increased the pyokori response to an upper limit of 3 days. Under 200 lux, 1000 lux, 1500 lux of illumination, the pyokori response increased gradually for the first 16, 10, or 6 hours after emergence, respectively, then it decreased rapidly until the response disappeared almost completely by 24, 16, or 12 hours after emergence, respectively. When the flies were kept under an intensive light for a few days, not only the pyokori response but phototaxis disappeared nearly completely in the bw; st ss strain. In such flies, almost no ERG was observed. Normal ERG pattern was observed in the flies kept under the red light or in the dark and 50 lux or 100 lux white light condition for a long time. The Hikone-H wild flies showed normal ERG in any light condition. From these results it may be supposed that the pyokori behaviour in bw; st ss strain has an important relationship with the existence of photoreceptor or photopigment in ommatidia of compound eye.