Uric acid metabolism modulates diet-dependent responses to intraspecific competition in Drosophila larvae

Intraspecific competition drives ecological specialization, and niche expansion. In holometabolous insects, larval intraspecific competition (“crowding”) has lasting fitness consequences for individuals and shapes adaptive responses. However, our understanding of the molecular profile of larval crowding responses remains allusive. Here, I used a genetic construct in Drosophila melanogaster with disrupted uric acid metabolism (uro(−)) to demonstrate the role of the uric acid metabolism—and its interactive effects with larval crowding, diet, and urea concentration—on female oviposition and larval development. Uro(−) larvae developed faster in sugar-rich diets. However, uro(−) larvae pupated at lower heights in protein- and sugar-rich diets in crowded larval conditions and showed slower development in protein-rich mixed-genotype environments. uro(−) did not affect female oviposition nor larval pupation success. Overall, this study provides the first step toward an integrated understanding of the molecular pathways underpinning the responses to intraspecific competition in holometabolous insects.