Figure 2. Enrichment of mosquito and midge larvae collected from Sarracenia purpurea pitchers.

The arrows connect points showing enrichment after 3 and 72 hours of plants at Tom Swamp in Massachusetts that were fed ¹⁵N as ammonium nitrate (¹⁵NH₄ ¹⁵NO₃), uniformly-labeled (U-) ¹³C-¹⁵N-glycine or U-¹³C-¹⁵N-phenylalanine alone (IN, U-Gly, and U-Phe, respectively) or in combination (IN+, Gly+, and Phe+, respectively). Larvae in pitchers fed Phe or Phe+ had the highest ¹³C and ¹⁵N enrichment after 72 hours.