Larval stop,delayed development and survival in overcrowded cultures of Drosophila melanogaster: Effect of urea and uric acid

Uric acid and urea added to non-crowded cultures of D. Melanogaster are able to reproduce the larval stop (cessation in development) detected in highly competitive situations. The quantitative analysis of media as well as of larvae and pupae reveals the presence of both compounds as natural waste products of nitrogen metabolism in Drosophila. The nature of their effect is discussed in terms of larval intoxication as a mechanism which may account for the effects usually observed in crowded cultures: development delay, lower survival and also larval stop (which can only be detected by interrupting the competitive process by an overfeeding technique).