Actually Reese created the Replicators in the milky way. She was an android and considered them as her toys but they start to replicate and got out of control. (see episode "Menace")
Asuran on the other hand were created by the Ancients to fight the Wraiths.
Actually the replicates where created by the ancients but when they left the Pegasus galaxy to come to earth one of the ancients built Reese which made the bug like replicators in the milky way. You where close but all in all the replicators where built by the ancients.
