So long as they are appropriately dehydrated, there will be no mold growth on dried slices. Mold only appears if the drying process is timely and needs to be done for an adequate time. Even if the slices feel tacky just after being taken out of the oven, their contact with the atmosphere as decorations will guarantee further protection against mold. Unless you live in a highly moist climate, mold should not be a worry after drying. When dried, they will not attract bugs either.