Megginson was once seen as a future star, but has been overtaken in the Pittodrie pecking order by younger forwards Ryan Fraser, Josh Magennis, Cammy Smith and Declan McManus - who scored twice for the Aberdeen U20s in Dingwall yesterday.
Dons boss Craig Brown insisists the 20-year-old is an important part of his plans.
Alloa are managed by former Dons captain Paul Hartley.