Even fewer of those released successfully establish and control the weed. Biological control is most effective when used together with other compatible pest control practices in an integrated pest management program. Mechanical control or herbicide control programs for aquatic weed can be combined with biological control to provide such a program. When combining techniques it is a good practice to maintain an otherwise uncontrolled area of plants for the insects to use as a nursery to establish and build up. Mechanical control includes mowing, hoeing, cultivation, and hand pulling.
Chemical control is the use of herbicides.
You can also use a combination of these three methods in an integrated weed management approach which some authorities would consider as the fourth method. The main concern is a host shift of a biological control agent that results in the agent feeding on a desirable plant. Biological control agents are not available for all target pests. Some of the target weeds are closely related to plants that are desirable so the risk of introducing an agent is too great. Research time and money is needed to locate biological agents and screen them for host range before the agents are released.