Characterization of Molting Process during the Different Developmental Stages of the Diamondback Moth Plutella xylostella

SIMPLE SUMMARY: The diamondback moth, Plutella xylostella (L.) is the most important pests of cruciferous crops worldwide. Although there are numerous studies on the general life cycle of P. xylostella, the detailed descriptions of the morphological transformation and behavioral sequence during molting are rarely provided and visualized. In this paper, we provided the duration and photographic details of staging criteria of each stage of egg hatching, larval–larval ecdysis, larval–pupal metamorphosis and adult eclosion, and post-eclosion behavior of P. xylostella. Several new characters in the molting process that were previously not described in other lepidopteran insects were found, i.e., the larvae contracted anterior-posteriorly then dorsal-ventrally during pre-ecdysis, and the antennae waved backward then forward in the post-eclosion behavior. Our findings add an important piece of knowledge about the molting biology of lepidopteran insects. ABSTRACT: The molting process of the lepidopteran insects is observed for many species. However, the detailed description of the morphological transformation and behavioral sequence during molting are rarely provided and visualized. Here, we described the molting process of the diamondback moth Plutella xylostella by providing the duration and photographic details of staging criteria of each stage using stereo microscopy and a digital video camera. We divided the morphological transformation of egg development and hatching into five stages, the larval–larval ecdysis and the larval–pupal metamorphosis into five stages, the pupal development and eclosion into three stages, and the post-eclosion behavior into four stages. Several new characters in the molting process that were not previously described in other lepidopteran insects were found, i.e., the larvae contracted anterior-posteriorly then dorsal-ventrally during pre-ecdysis, and the antennae waved backward then forward in the post-eclosion behavior. Our findings will deepen the knowledge of the molting biology of lepidopteran insects and facilitate the study of the underlying mechanisms.