nosema bombycis nosema bombycis nosema bombycis is a species of microsporidia of the genus nosema infecting silkworms, responsible for pébrine. this species was the first microsporidium described, when pebrine decimated silkworms in farms in the mid-19th century. this description was made by carl nägeli. louis pasteur, taking up an idea of osimo which had not been successful, showed breeders a practical way to select uninfected individuals to recreate new healthy farms. nosema bombycis scientific classification phylum: microsporidia family: nosematidae genus: nosema species: n. bombycis binomial name nosema bombycisnägeli, 1857