The roots of the invasive plant Centaurea diffusa release 8-hydroxyquinoline, which has a negative effect on plants that have not co-evolved with it.
Thirteen biological pest control agents have been used against this plant and its cogener, diffuse knapweed, including the moths Agapeta zoegana and Metzneria paucipunctella, the weevils Bangasternus fausti, Larinus obtusus, and Larinus minutus and Cyphocleonus achates, and the fruit flies Chaetorellia acrolophi, Urophora affinis and Urophora quadrifasciata.