Graphical Abstract (IMAGE) Max Planck Institute for Chemical Ecology Caption Enterococcus mundtii gut bacteria (yellow) form a biofilm on the mucus layer of the African cotton leafworm Spodoptera littoralis. The symbiotic bacteria produce a channel-forming peptide called mundticin: In the gut of the leafworm, the substance permeates the cell membrane of pathobiont cells (blue and pink), eventually causing cell death. Symbiont cells (green), such as Clostridia and other E. mundtii bacteria are insensitive to mundticin. Credit Yongqi Shao, Zhejiang University, Hangzhou, China Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.