The present invention provides antifungal and antibacterial peptides, especially antifungal peptides obtained from insect species, particularly lepidopterans. The present invention also provides methods of using these antifungal peptides to treat or prevent fungal growth for a variety of purposes such as; protecting plants from fungal infections, treating fungal infections of animals, especially humans, and prevention of food spoilage. In particular, the invention provides transgenic plants that produce an antifungal peptide, said plants having increased resistance to fungal infections/growth.