A variety
of approaches exist to deal with invasive species, and one of the most
prominent methods has been to introduce biological controls, or biocontrol.
Essentially, this method fights fire with fire by introducing another foreign
species to take care of the foreign species that has invaded the local
environment. Typically, for example, insects are introduced to control invasive
plants. One of the major benefits of biocontrols is that, if effective, it can
reduce or eliminate the need for chemical controls like pesticides or
herbicides. Quarantine studies are conducted to see whether a potential
biocontrol is suitable for the affected habitat, and to determine host
specificity – that is, whether the biocontrol will affect only the invasive
species and not become invasive itself. Host specificity can be one of the big
benefits of biocontrol, in that organisms with specific diets can target
invasive species more precisely than chemicals, which often affect an array of
plants, animals and qualities within in an ecosystem. One of the major
drawbacks to biocontrol, however, is that it is not very reversible. Whereas
chemical applications can cease when environmental damage is detected, it’s
difficult if not impossible to eradicate a biocontrol species once it has
established itself as an invader. Furthermore, host specificity is not an
absolute requirement of biocontrol species introduction, and many biocontrol
proponents urge the introduction of non-host-specific agents. Serious problems
may then arise when species switch hosts, start attacking native plants, or
other biocontrol agents.
Biocontrol is widely used, but has
had a mixed track record, in some instances proving safe and hugely effective,
and in others becoming major boondoggles. An example of a great biocontrol
success can be found in the handling of alligatorweed, which by the 1950s had
become a huge problem here in Jacksonville, infesting local waterways and
wetlands. After various studies, alligatatorweed flea beetles and two other
insects were released into affected areas and it worked so well that within
three years, the U.S. Army Corps of Engineers completely stopped herbicide
application to control the weed.
Sometimes biocontrol agents turn
out to be thoroughly mediocre. For instance, the aquatic plant hydrilla remains
problematic throughout Florida and no biocontrol efforts have yet proven very effective.
Several host-specific insects were identified and introduced to control
hydrilla, but each has its drawbacks and have not been up to the task of taking
down the weed, which in ideal conditions can grow up to ten inches each day! Some
places have been introducing grass carp fish to control hydrilla populations. The
grass carp eat even faster than hydrilla can spread, so it has no problem
eliminating outbreaks – however, these fish do not feed only on the weed and
thus they are prime candidates for becoming invasive, nuisance species
themselves! As such, grass carp stocking requires a permit in Florida and
generally is only done in smaller lakes and ponds.
On the other side of the coin, the Bufo toad (or Cane toad) is a very good
example - or rather, very bad - of biocontrol gone wrong in Florida. Native to
Central America, this toad was intentionally introduced to Hawaii, Florida, Australia,
and other tropical locations in order to control sugar cane beetles and other
pesky insects interfering with sugar production. In Australia, the introduction
was a major mistake as it was completely ineffective in combating their beetle
problem, and merely became a problem itself. The Bufo has also become a major
pest in South Florida, where it has become extremely well-established, since it
breeds year-round, will eat almost anything, and thrives in the moist
landscape. Unfortunately, the Bufo’s skin secretes a highly toxic fluid that
has killed many native animals and domestic pets that attempt to eat the toad,
and can also cause skin and eye irritation in humans. Today, the Bufo is
well-known and thoroughly hated by South Floridians, and can serve as a hard
lesson of the importance of caution in introducing biocontrol agents.
-Amanda Hudson, Legal Intern
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