Oral uptake of microsporidia carried by the invasive ladybird Harmonia axyridis can kill the native ladybird Adalia bipunctata. Genes encoding antimicrobial peptides are expanded in H. axyridis relative to Adalia bipunctata and Coccinella septempuncata. Inducible levels of some antimicrobial peptides were higher in H. axyridis compared to A. bipunctata and C. septempuncata.