Biological stoichiometry of growth in Drosophila melanogaster.

We examined the relationship between growth rate, C:N:P stoichiometry, and nucleic acid content in Drosophila melanogaster. The "Growth Rate Hypothesis" predicts that N and P contents per unit body mass will be high during ontogenetic stages characterized by rapid growth, reflecting the large requirement for P-rich ribosomal RNA during these periods. The ratio of RNA:DNA also is predicted to change with changes in growth rate. Growth is rapid in early D. melanogaster larvae, slowing considerably just prior to pupation. As predicted, a positive relationship was found between growth rate and N and P content, but not C. Thus, body C:P and N:P ratios declined with increasing growth rate. The relationship between RNA content and growth rate also was positive. Additionally, the fraction of total body P contributed by ribosomal RNA increased with increasing growth rate.