Extraction and partial characterization of pupal-cuticle-melanizing hormone (PCMH) in the swallowtail butterfly, Papilio xuthus L. (Lepidoptera, Papilionidae)

The pupae of Papilio xuthus show green, brown, and orange color polymorphis m. The color of the pupal body is determined by a hormone that produces bro wn coloration, a hormone called pupal-cuticle-melanizing hormone (PCMH) whi ch is secreted from brain-suboesophageal ganglion and prothoracic ganglion (Br-SG-PG) complexes during the pharate pupal stage. PCMH was extracted wit h 2% NaCl from Br-SG-PG complexes of P. xuthus green pupae. When pharate pu pae producing brown pupae (brown-pupa-producers) were ligatured between the thorax and abdomen with cotton thread, the head-thorax complex developed i nto the brown type and the abdomens into the green type. Ligatured abdomens treated with crude PCMH produced intermediates of green- and brown-pupae ( melanization degree of grades 0-3), which was used to assay PCMH-activity. Extracts of Br-SG complexes from Bombyx mori adults also shifted the color of the pupal cuticle toward the brown type in ligatured P. xuthus abdomens of brown-pupa-producers. The molecular weight of the B. mori factor showing PCMH activity (PCMH-active factor) was estimated to be 3,000-4,000 Da by g el filtration. The PCMH-active factor is a hydrophobic peptide(s) that bind s to a cation exchange resin at pH 6.9.