Author Contributions
This study was designed by SN, NJ, CWW and MC. Wild butterflies were collected by SN, NJ. Larval rearing, switch experiment and gut sampling was performed by MC. RNA-extractions were done by MC (Switch A) and KS (Switch B). Data were analysed by KS, RAS, DM and SN. The manuscript was written by KS with the help of all the authors.