Biological control

Biological control is the deliberate introduction of an organism whose feeding preferences or pathology suppress a target invasive. Major agents in US aquatic vegetation: triploid (sterile) grass carp for hydrilla and pondweeds; hyacinth weevils (Neochetina eichhorniae and N. bruchi) for water hyacinth; the alligator weed flea beetle (Agasicles hygrophila) for alligator weed; and salvinia weevils (Cyrtobagous salviniae) for giant salvinia. Highly species-specific and self-sustaining once established, but slow — full effect takes 1–3 seasons. Permit required in nearly all states.