Oviposition pattern of several Drosophila species under various light environments

The oviposition pattern over two continuous days under constant light (LL) and light-and-dark (LD) conditions was studied by means of a special apparatus; four Drosophila species (D. lutescens, D. melanogaster, D. hydei, and D. virilis) were used. The results showed that: (1) Under the LL condition, the oviposition pattern was characteristic for each species. The number of eggs laid by D. lutescens was smaller than that laid by the other species, and the oviposition pattern of this species was rhythmical. Females of D. melanogaster laid eggs continuously, but at a low rate. In contrast, D. hydei and D. virilis laid eggs in clusters, the total numbers of eggs being larger than those of D. lutescens and D. melanogaster. (2) Females of three species (D. lutescens, D. melanogaster, and D. virilis) laid more eggs in the light phase than in the dark phase under the LD condition. However, no consistent trend was obtained with D. hydei, suggesting that the oviposition pattern of this species is indifferent to the light condition (i.e., it is independent of it). (3) No effects of pre-experimental light condition on the oviposition were found for any of the species. The light-dependency of the oviposition pattern is discussed from the viewpoint of adaptation.