Center For Aquatic And Invasive Plants

Biological Control

Florida’s native plant populations are regulated by environmental factors and natural enemies. These natural enemies, such as insects, fish, and pathogens, play an important role in keeping the native plant population in check. When a non-native plant is introduced into a Florida habitat, it may out-compete native plant populations because its natural enemies are not present.

Biological control is a management strategy that aims to reunite these natural enemies with the established, invasive plant species.

Biological control agents are used to decrease the invasive plants' competitive advantages over native plants, and to weaken the invading population by increasing leaf mortality, decreasing plant size, reducing flower and seed production, and/or limiting population expansion.

It should be noted that years of research are required by law to ensure the introduced natural enemies are “target specific.” It must be proven that they only attack the specific plant in need of control.

Section Topics

The process of developing a successful biological control agent:

1. Discovery and identification of the target plant’s natural enemies

2. Approval for importation and study in the U.S.

3. Quarantine laboratory studies to ensure that the organism will affect only the target plant species and will not impact native or crop species

4. Initial field release and establishment of natural enemy populations

5. Monitoring for success and additional releases

Biological Control Approaches

Classical Biological Control: A biological control agent is imported into the U.S. after extensive study and allowed to establish a reproducing population. This is the most commonly used biological control method

Non-classical Biological Control: Mass rearing and periodic release of resident biological control agents (native or introduced) to increase their effectiveness

Adventive Biological Control: Regulation of a pest population by a natural enemy that has arrived from elsewhere without deliberate introduction

Biological Control Considerations

It may not always be possible to find a biocontrol agent that effectively controls and attacks the selected non-native plant. When potential biocontrol agents are identified, their establishment and suppression of the target plant species in the introduced area are not guaranteed.

Even if biocontrol agents do successfully establish in their introduced areas, control is not immediate, and agents may require many years to have a major impact on target weeds. Finally, once a biocontrol agent is established, it cannot be recalled if desirable nontarget species are affected by the agent.

All of these considerations are taken into account when determining whether to include biological control as a strategy for managing invasive plants in Florida.

Adapted from:
Biology and Control of Aquatic Plants — A Best Management Practices Handbook, Chapter 8: Introduction to Biological Control of Aquatic Weeds; pp 47-53; by James P Cuda, University of Florida; published by the Aquatic Ecosystem Restoration Foundation