The widely accepted paradigm that epoxidized methyl farnesoates (“juvenile hormones,”
JHs) are the principal sesquiterpenoid hormones regulating insect metamorphosis was
assessed in Drosophila melanogaster. GC–MS analysis of circulating methyl farnesoids
during the mid to late 3rd instar showed that methyl farnesoate is predominant over methyl
epoxyfarnesoate (= JH III). The circulating concentration of methyl farnesoate (reaching
nearly 500nM), was easily high enough on a kinetic basis to load the Drosophila ortholog of …