Euborellia annulipes (Dermaptera: Anisolabididae), the ring-legged earwig, a model for oogenesis and development studies in insects

The knowledge about many aspects of insect biology and development comes mainly from a unique model, the vinegar fly, Drosophila melanogaster. Consequently, we have probably overlooked ancestral features of the class Insecta as well as unique traits of specific orders, hindering a more complete understanding of the evolutionary history of this important group of organisms. In the last years, the advances in molecular tools and imaging techniques have allowed the emergence of new insect models, thus beginning to decipher the morphogenetic bases behind the formation and evolution of the vast diversity of shapes, sizes, and patterns that characterize them. Earwigs are cosmopolitan hemimetabolous insects with a flattened body, characteristic abdominal pincers, and maternal care behavior. Due to their basally branching phylogenetic position, they are ideal to address questions regarding ancestral traits of insects. However, their reproduction and embryonic development have been poorly studied in laboratory conditions. Here we described the ring-legged earwig Euborellia annulipes life cycle from embryogenesis through nymphal to adult stages, its reproduction, and essential morphological and behavioral characters. Additionally, using confocal and transmission electron microscopy we also analyzed in detail the morphogenesis of its primitive meroistic polytrophic ovary. Our aim is to provide an emerging model system with a strategic phylogenetic position to perform comparative studies on insect oogenesis, development, and morphological evolution.