Food Level in Relation to Rate of Development and Eye Pigmentation in Drosophila Melanogaster

In the development of larvae of Drosophila melanogaster an organizational change takes place at about 70 hours after egg-laying (25° C.). This change is referred to as the "70-hour change." Larvae deprived of all food for periods at any time up to the 70-hour change are retarded in development, the retardation being a function of the length of the starvation period. Larvae deprived of food after the 70-hour change are not retarded, but are probably somewhat accelerated in development. If deprived of food during a portion of the larval developmental period after the 70-hour change, the final size attained by the fly appears to depend largely on the proportion of this period spent on full food. Periods of complete removal of food from vermilion brown larvae are without apparent effect on eye pigment production. This is true whether the starvation period be short or long and whether it comes before or after the 70-hour change. Partial starvation (at intermediate food levels) of larvae, under certain conditions, greatly increases the amount of eye pigment formed by vermilion brown flies. The period of development most sensitive to this "starvation effect" on pigment production by the eye, lies shortly before the 70-hour change. The production of a supposedly specific eye color hormone, v+ hormone, can be influenced greatly by the amount of food given to vermilion brown larvae during a limited period of development, the period of maximum sensitivity referred to above. This increase is not less than a hundredfold.