Intraspecies variation of Metarhizium brunneum against the green peach aphid, Myzus persicae, provides insight into the complexity of disease progression.

The observed intraspecies variation suggests that altered conidial adhesion to the nymph cuticle is a major factor affecting virulence. We prove the role of nymph ecdysis as a defense mechanism disrupting fungal infection. Because significant differences were observed between closely related isolates, this study emphasizes the importance of appropriate isolate selection for biological control. © 2021 Society of Chemical Industry.