Biocontrol: A Success Story!


Mexican Petunia is a Category 1 invasive species in Florida. 

by Megan Weeks, Cuplet Fern Chapter of FNPS

Florida’s biodiversity is made remarkable by the plants and animals that depend on one another for survival. This delicate yet imperative relationship maintains a healthy natural environment, where the population of plants and animals are balanced. When new species are introduced, natives can be outsourced and the natural balance risks being disrupted[1]. Biocontrol is one method to help restore a balanced environment.

Exotic species have been introduced to Florida both accidentally and intentionally. Most threatening to the natural balance are plants from tropical and sub-tropical regions which are suited to Florida climate and often “take root” in this foreign land[1]. These non-native species do not serve as a significant food source for Florida organisms and are able to outcompete native plants for resources[1]. When an exotic species that is not affected by predators or pathogens becomes established, then the population will grow uninhibited and can potentially become invasive. Approximately one-third of vegetation found in Florida’s natural lands is exotic, and roughly 11% of those species are considered invasive[2].

The air potato beetle is released into an area overrun
by the invasive vine .
Biologists have long struggled to prevent the exotic populations from encroaching on endemic habitats. Manual methods, such as applying chemicals, hand pulling and burning, may help tame invasive populations but are often not a reliable long term solution[3]. As an alternative, scientists spend years researching predators (insects, pathogens, and fish) to target specific invasive species in a method called Biocontrol. This method relies on the predator to consume or destroy the exotic species, restoring ecological balance[1].

Air Potato Beetle. Photo by Mary Keim

In 1905 Dioscorea bulbifera, the air potato, was introduced to Florida and with no natural predators the exotic vine quickly became a threat to native plants[2]. The infamy of this invasive species grew almost as rapidly as the plant itself and is a major concern for the Department of Agriculture[2]. A biocontrol program was launched to find a predator that would consume or destroy the air potato. Scientists returned to Asia where D. bulbifera is endemic and found a small beetle that could survive by eating the invasive plant[4]. Extensive research was performed to ensure that the beetle would not further disrupt the ecological balance.

In 2012 the air potato leaf beetle was finally released to feast on the air potato. Scientists note that the beetle mostly consumes the soft tissues found on the leaves and growing tips which creates difficult growing circumstances and can hinder the plant’s biological processes[5]. Every year between May and October, during peak air potato growth, new batches of the beetle are released[1].

Larva of the Air Potato Leaf Beetle eating air potato leaves.
Photo by Donna Bollenbach 
The air potato leaf beetle is very selective in its diet and only consumes D. bulbifera even excluding all other species of Dioscorea[3]. Research done by the University of Florida has found that beetle establishment in release sites has led to “reduced height of vines, decreased bulbil production, and most importantly, an increase in native vegetation”[3].

Seminole county is one of the release sites for this remarkable and successful form of biocontrol. Through this biocontrol program, professionals were able to contribute to the restoration of Florida’s ecological balance. The air potato leaf beetle is an investment for our future and a vital part of the preservation and conservation of our natural lands. To find out more about the amazing air potato leaf beetle check out the USDAs website: bcrcl.ifas. ufl.edu/airpotatofiles/aboutairpotatoprogram.shtml

[1] plants.ifas.ufl.edu/manage/control-methods/biological-control/
[2 www.fleppc.org/Manage_Plans/AirpotatoManagementPlan_Final.pdf 
[3]plants.ifas.ufl.edu/plant-directory/dioscorea-bulbifera/ 
[4] bcrcl.ifas.ufl.edu/airpotatofiles/aboutairpotatoprogram.shtml 
[5] entnemdept.ufl.edu/creatures/BENEFICIAL/BEETLES/air_potato_leaf_beetle.htm

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This blog was reprinted with permission from the Frond Forum, the newsletter of the Cuplet Fern Chapter of the Florida Native Plant Society. If your chapter publishes informative articles that you would like to share, please send them to me for review. I am especially interested in getting plant profiles and "What's in Bloom?" from different areas of the state.

Donna Bollenbach, Social Media Director/FNPS

Comments

Anonymous said…
Releasing another non-native insect into the wild to counter the progress of a non-native plant is highly controversial at the very least. I wonder if decades from now, we will look at this post happily or angrily should the non-native insect evolve over time to become a pest to native plants once it depletes the air potato populations that sustain them. The success of any organism depends on it's evolutionary resourcefulness and flexibility to it's surroundings. For our sake, I hope for the former so we do not lament in hindsight for releasing yet another non-native into the wild.

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