A case for multiple oscillators controlling different circadian rhythms inDrosophila melanogaster

A population of the fruit fly Drosophila melanogaster was raised in periodi c light/dark (LD) cycles of 12:12 h for about 35 generations. Eclosion, loc omotor activity, and oviposition were found to be rhythmic in these flies, when assayed in constant laboratory conditions where the light intensity, t emperature, humidity and other factors which could possibly act as time cue for these flies, were kept constant. These rhythms also entrained to a LD cycle of 12:12 h in the laboratory with each of them adopting a different t emporal niche. The free-running periods (tau) of the eclosion, locomotor ac tivity and oviposition rhythms were significantly different from each other . The peak of eclosion and the onset of locomotor activity occurred during the light phase of the LID cycle. whereas the peak of oviposition was found to occur during the dark phase of the LID cycle. Based on these results, w e conclude that different circadian oscillators control the eclosion, locom otor activity and oviposition rhythms in the fruit fly D. melanogaster. (C) 2001 Published by Elsevier Science Ltd.