Experimental studies on the duration of life. XIII. The influence of different feeding on the duration of life of the imago of Drosophila melanogaster
American Naturalist 64(690): 37-55
Summarizing, it has been shown in this paper that : (1) The relation between the duration of life and different factors is expressed by quite different types of curves. Temperature and duration of life are connected by a simple exponential curve, while starvation (data from KopeC) and duration of life at different grades of intermittent starvation can be represented by the upper part of a logistic curve. (2) Drosophila females emerged from larvae taken from the food before the end of the normal larval feed-ing do not differ in their duration of life from the controls. The males show even a longer (although statistically not very significant) duration of life as compared with the controls. This shows that a reduction in body size does not lead inevitably to a reduction of the duration of life, as has been the case with "room" and "cold" temperature flies which differed in size of the body and of the duration of life. (3) Keeping flies on synthetic food with yeast and without it indicates that absence of yeast reduces greatly the duration of life of males and females. Very likely the carbohydrates available in the synthetic food are not sufficient for nutrition of adult Drosophila, and additional substances included in living yeast cells are required. (4) Changing synthetic food with yeast every day and every second day indicates that the female duration of life is not affected by this procedure, while males in this experiment show a much shorter duration of life when transferred to new bottles every day. This difference may perhaps be attributed to sex differences in metabolism, or food requirements of male and female organism. Every day food changing can possibly be considered as a partial starvation, because yeast shows growth only after twenty-four hours, and changing food every day does not permit the flies to have yeast growth in such abundance as in the case when the bottles are changed every second day. It is also possible that the results for the males in this particular experiment are not typical.