M-O. LC-ESI-MS/MS chromatograms of ALA in midguts of 14-day flies(M), 26-day flies (N), and 40-day flies (O). Arrows indicate the peak of ALA. The area of ALA peak indicates the content of ALA. cps: counts per second. MRM: Multiple Reaction Ronitoring. When the estimated peak of ALA is undetected in the chromatogram, the content of ALA is considered as 0. 