Regulation of metamorphosis in neopteran insects is conserved in the paleopteran <i>Cloeon dipterum</i> (Ephemeroptera)
Orathai Kamsoi, Alba Ventós-Alfonso, Fernando Casares, Isabel Almudí, Xavier Bellés
Abstract
Significance Mayflies are the only extant insects that molt after having formed wings, in a stage called subimago. Numerous authors have wondered whether this stage is a nymph, an adult, or a kind of intermediate. Another question is why mayflies have a subimago stage, when molting a wing is risky. Working with Cloeon dipterum , we found that metamorphosis is regulated as in neopteran insects and that it is determined prior to the formation of the subimago. Thus, it should be considered an instar of the adult stage. We also found that the forelegs grow dramatically between the last nymphal instar, the subimago, and the adult. That necessary growth may help to explain the functional sense of the subimago.