Theoretically, no you won't need a PPL for UPT, but your odds without one are slim to none unless an in-unit star enlisted troop. In 18 years and 20+ UPT students, not one didn't have at least a PPL. The guy I mentioned had only a PPL and less than 100 hours. At the other extreme, a B747 pilot got the nod. Story is too specific for the telling here.
GF