Transformation Of Internal Structures During The Metamorphosis Of Chrysopa Pallens (Rambur,1838) (Neuroptera:Chrysopidae) Based On 3D Reconstruction

Chrysopa pallens (Rambur, 1838) belongs to Chrysopidae. The green lacewing is one of the most common encountered families of insect in the order Neurptera. They distributed in all major biogeographic regions of the world. Also they play a very important role in biological control of pests.Their economic value has been paid much attention for a long time. Thus, the external morphology and biological characteristics have been well studied. However, the detailed information of the internal structures such as the musculature remained scarce and virtually no information was available on the anatomy of pupae and on the changes undergone by internal structures during metamorphosis.Studies on the internal morphology take an important part in the insect taxonomy and morphology.The detailed information of internal system in different developmental stages is crucial to better understanding complete metamorphosis and their ecological adaptability from the basic morphological view. Additionally, it can help us better understanding the phylogenetic relationship among endopterygote groups and among the families of a certain order.The ?-CT and the conspicuous lack of informationon metamorphosis in lacewings induced us to execute this study of the skeleto-muscular system of the head and thorax, as well as the cephalic system,the digestive system, and the tracheal system. It covers all the crucial stages of the life cycle of Chrysopa pallens (Rambur, 1838): the final larval instar, the pupal stage (from Day 1 to Day 12), and the adults ((?)). The transformations of these systems during pupal stage are studied for the first time.The homologization of the morphological differences and the functional adaptation between the stages were assessed. They were examined by a combination of ?-computed tomography and computer-based 3D reconstruction.The results show that the muscles are distinctly slender in larvae than in adults with a significantly larger quantity. The tracheal system is thinner in larvae than in adults. The midgut is a large sac with a blind end in larval stage with storage excretion, which indicates the food is always stored in midgut during larval and pupal stages. Most of these transformations are related to tasks they play in the developmental stages. A larger brain with improved sensory perception is suggested to be essential for dispersal, mating and flying for adults. For the pupae, the results show that the histolysis of the muscles happens in first third of the pupal period and their reconstruction happens in the following days. The brain and tracheal system exist all along. For the digestive system, the midgut and hindgut are connected after the emergence. We suggest the transformations of the skeleton and the digestive system occur earlier than the nervous system and the musculature.Comparative morphological studies for cephalic and thoracic musculature are based on the the published mophological data in other groups, such as Coleoptera, Diptera, Mecoptera and Hemiptera.The comparitions for internal features of the thorax between alate and wingless morphs are discussed.