Detection of juvenile hormone I, II and III in adult monarch butterflies (Danaus plexippus)

Abstract Hemolymph of Danaus plexippus (monarch butterfly) was analyzed for juvenile hormone titer by gas liquid chromatography-mass spectrometry (GC-MS) in the selected ion monitoring mode. Laboratory reared, reproductively active, adult males and females contained JH I, II and III. JH II predominated with titers ranging from 2.3 to 11 ng/ml hemolymph. Titers of JH I and JH III were approx. 1 order of magnitude lower than those of JH II. JH I, II and III acids were also detected, but at levels generally lower than the corresponding JHs. JH titers in field collected reproductively inactive, gregarious adult monarchs, were 1–2 orders of magnitude lower than those of laboratory reared reproductively active monarchs. JH II was again the predominant JH in these animals.