Fig. 1.

The iridoid pathways in plants, aphids, and beetles evolved independently from each other. While the plant and aphid pathways both lead to nepetalactol, the beetle Phaedon cochleariae produces a chrysomelidial. Enzymes, identified and characterized (5), are shown in bold. IDS, isoprenyl diphosphate synthase; TPS, terpene synthase; CYP, cytochrome P450 monooxygenase; SDR, short-chain dehydrogenase/reductase; and GMC, glucose–methanol–choline oxidoreductase. From ref. 5 and SI Appendix, Fig. S15.