"In the tanks that only held one kind of wasp, the second went extinct within a few generations"
That makes no sense at all.
I follow the thrust of the argument: that if one predator goes extinct, its prey thrives, outcompetes another prey species, second prey species either goes extinct or is at least severely reduced in numbers, predator that preys on now extinct prey species goes extinct.
But I don't think the predator that wasn't in the tank in the first place would take "a few generations" to disappear.