A new neoclerodane diterpenoid, clerodendrin I, was isolated from leaves of Clerodendron trichotomum as a feeding stimulant of the turnip sawfly, Athalia rosae ruficornis, and characterized as a threo epimer of clerodendrin F in the 2,3-diacetoxy-2-methylbutanoyloxy moiety at the C-3β position.
Several pharmacophagous insects have been shown to sequester specific kairomonal substances or their derivatives in their body tissues. Turnip sawflies,Athalia rosae, visit a plant,Clerodendron trichototmum (Verbenaceae), and feed voraciously on the leaf surface. Clerodendrins were characterized as