Researchers from Freie Universität Berlin, Princeton University, and Leibniz Institute of Freshwater Ecology and Inland Fisheries investigated whether insects with a pupal stage grow faster than insects that do not go through this process. The former group of holometabolic insects includes beetles, butterflies, hymenoptera, and flies, while the latter group of hemimetabolous insects includes aphids, crickets, and grasshoppers, which do not have a pupal stage. The larvae of holometabolic insects do indeed grow much faster than other insect types.

In order to demonstrate that rapid growth by means of a pupal stage is evolutionarily advantageous a mathematical model was created in cooperation with Professor Jessica Metcalf from Princeton. “The findings produced by combining data from different insect species with and without pupal stages and using a mathematical model strongly indicate that the complete evolution of insects came about as this is the only way of ensuring rapid growth, which is also ecologically beneficial,” says first author of the study Dr. Christin Manthey, an evolutionary biologist who now works at the Max Planck Institute for Chemical Ecology in Jena, Germany.

“There are also other hypotheses out there that try to explain why insects undergo metamorphosis, but these have yet to be investigated,” says principal investigator Professor Jens Rolff, a biologist at Freie Universität Berlin. “In light of the important role that insects play in our ecosystems as well as in our food production, as both pollinators and herbivores, this fundamental aspect of their biology is vital to better understanding these insects.”