Melanization and Reddishi Coloration Hormone (MRCH)Activity in Developing Embryos of the Saturniid Silkmoth, Samia cynthia ricini DONOVAN (Lepidoptera : Saturniidae)

Abstract

Melanization and reddish coloration hormone (MRCH) activity was observed in developing embryos of the saturniid silkmoth Samia cynthia ricini (DONOVAN). The embryonic MRCH elicited larval coloration of isolated abdomens of penultimate instar larvae in the armyworm, Pseudaletia separata (WALKER). The embryonic MRCH of Samia also caused melanization in the common cutworm Spodoptera litura (FABRICIUS). The MRCH activity was detected in a whole developmental stage of Samia embryos, and the maximal MRCH activity was found in embryos at 8 days after oviposition, just prior to hatching. These results suggest that an increased activity in developing embryos corresponds to the differentiation status of their neuroendcrine systems.