In a new study in PNAS, researchers from the Max Planck Institute for Chemical Ecology and the University of Mainz, together with an international team, showed that the genome of symbiotic bacteria of beewolves is in the process of being reduced to their important protective function: the production of antibiotics. The genome of these bacteria is of great interest for understanding the process of genome erosion and elucidating how the cooperation and the mutual benefit between bacteria and their host insects have evolved over long periods of time.