*Cactoblastis cactorum* as an Invasive Species in the United States\
By: Dillon McGinnis

*Cactoblastis cactorum,* also known as the South American Cactus Moth,
has become a serious threat to Opuntia (prickly pear cactus) species in
the southern United States. The cactus moth was found in the United
States in 1989, in Florida, and has since then expanded its range north
and west on both Atlantic and Gulf coasts. The moth was once considered
"the undisputed poster child for biological control for weeds because of
its dramatic role in reducing expansive populations of invasive prickly
pear cacti in Australia, South Africa, Mauritius and the Hawaiian
Islands" (Bloem, 2005); however, in the United States we must control
the spread of the cactus moth in order to protect Opuntia species, not
eliminate them. Opuntia species in the United States are not invasive
species and spreading of the cactus moth will eventually lead to severe
effects on western United States and Mexico desert ecosystems. We must
act now in order to prevent further spread of the cactus moth because
"\[n\]o satisfactory method of chemical control of C. Cactorum is known.
The widespread use of pesticides is not recommended because of the
occurrence of rare and endangered fauna..." (Habeck & Bennett).

Because no method of chemical control is available we must regulate and
prevent the further spread of the moth since "80+ Native Opuntia species
could be affected, threatening important sources of food, medicine, and
emergency fodder" (NISC, 2005). These Opuntia keep not only desert
ecosystems in equilibrium but also provide essential products to many
cultures and societies. Many cultures have relied on the fruit from the
cactus as a way of surviving whether it is that they trade it or eat it.
The spread is happening not only through natural dispersal but by human
aided transportation of infected cactus plants in nurseries and gardens.
APHIS was first to bring attention of the potential impact of the cactus
moth, and under the United States Department of Agriculture (USDA), has
proposed a rule (7 CFR part 301 subpart 301.55 to 301.55-9) to regulate
and restrict interstate movement of the South American Cactus moth host
material from infested areas of the United States to help prevent the
artificial spread of the South American cactus moth (73 Fed. Reg).
Clearly, this rule must be amended in order to stop the social,
economic, and environmental impacts of *Cactoblastis cactorum.*

First, why is the *Cactoblastis cactorum* an invasive insect?
Invasiveness of the cactus moth is due to its quick generation time and
large egg yield by the female, resulting in a feeding frenzy on the
cacti. The cactus moth, already in Florida, feeds on the pads of all six
Opuntia species including the rare and endangered (Simonson, et al.,
2005). The moth's eggs are stacked on top of each other to look like
spines making it hard to tell the eggs are not part of the Cactus. When
the eggs are hatched the caterpillars start to cause physical damage by
hollowing out and destroying the young parts of the cactus that are not
yet strong. (Zimmerman & Bloem, 2004). The feeding caterpillars cause
rotting in the cactus and allow microbial pathogens which are simply
microbes that carry and cause disease to enter the cactus which also
contributes to the cactus's death. In fact, once these eggs are hatched
"\[t\]he caterpillars of this moth are capable of complete destruction
of entire plants and stands of cacti" (Mississippi State University
GeoResources Institute, 2007).

Another invasive factor of the moth is that since 2001 the moth has been
spreading at a pace of about 160km per year and once the moth reaches
the southwest desert there will be 31 species of prickly pear cacti that
are at risk 9 of these cacti are endemic (Bloem,2005). These moths are
completely suitable for the southern United States because of the ideal
weather which enables them to have an easy dispersion throughout the
south. Methods like the sterile insect technique (SIT) are being used to
"overwhelm the expanding population with sterile individuals, which
drastically reduces the probability of wild females mating with fertile,
wild males" (Durham, 2006). Unfortunately, this is still not enough to
control all aspects of the spread. The moths also disperses through
human error in the inspection of infected cactus parts which are later
shipped to other locations that could be suitable for the moth to live
and continue to reproduce. James Carpenter, a researcher with the USDA,
stated that if it gets too far, obviously the chance of controlling it
or stopping it would increase exponentially (Morgan, 2002).

In Mexico, the cactus moth is already rated high risk because there are
no climate restrictions for it. This means that the moth will reproduce
rapidly if it continues to spread, eventually making it much easier to
find its way into the continental United States. Already the moth is
known to occur in three hardiness zones in the United States and can be
expected to survive as far north as Charleston, SC and west to
California. It is predicted that by 2007 the cactus moth could spread to
the Louisiana-Texas border. (Simonson, et al., 2005). The cactuses that
reside in these areas are in need of extreme aid because the main food
the moth feeds on is Opuntia species and there are more than 30
documented different species of Opuntia that are suitable for host
plants. The Platyopuntia species is the most susceptible to damage
because of their flat prickly pear pads that are great for food. Because
of the easy potential dispersal it is absolutely essential to regulate
and restrict the interstate movement of the cactus moth through trains,
cars, other vehicles, or infested plants being shipped from factories
and nurseries to decrease the economic impact the moth will create.

If the continuing spread of the cactus moth does not stop the USA and
Mexico will have a huge economic loss. The United States and Mexico will
directly be affected because of the profitable import and export of
these cactuses. Economic impacts would consist of a lower crop yield and
lower value of the commodity. The spread of the moth would directly
affect market and non market values of Opuntia species because according
to Simonson (2005) prickly pear cactus fruits and vegetables are a huge
industry in Mexico and areas of the United States. This fruit is eaten
in both fresh and processed forms. Many Mexican-Americans enjoy this
fruit as a delicacy and the 21 million frozen fruits could result in
sales of \$356 million a year nationwide (Simonson, et al., 2005).

Mexico exports a significant amount of these edible cactuses to the
United States and around the world because of their ability to be
preserved, staying good for a long time, or shipped fresh to be eaten.
Total Opuntia production in Mexico is estimated at over 250,000 hectares
while 3,000,000 hectares of Opuntia-dominated areas are used for the
harvesting and collection of wild cactus (Simonson, et al., 2005).(1
hectare is 2.47 acres). It is obvious when looking at the dispersal
potential of the moth that this huge amount of land that is used for the
production of Opuntia products could quickly be swarmed with infesting
cactus moths if litigation doesn't limit transports of infected
material.

Increasing consumer demand in Opuntia can be seen through recent years.
The 2002 U.S. Census reported trade levels of these fresh vegetable and
fruits at over 75,000 metric tons which is valued at over \$27million
(Simonson, et al., 2005). 27 million dollars is sure a lot of trade that
would be lost between mainly the United States and Mexico if precautions
are not taken against the predator. In the United States imports of
nopals which are the vegetable part of the cactus were estimated to
range from 11,485 to 23,139 metric tons per year and imports of the tuna
which are the fruit part of the cactus ranged from 5,657 to 9,399 metric
tons per year (Simonson, et al., 2005). We can easily foreshadow that
this increase in demand will not decrease unless these valued cactuses
are wiped out and then consumer price will drastically soar.

With the increase in importance of exports, imports, and food the spread
of the cactus moth will also directly lead to the stunting of employment
in nurseries and landscaping in the south where this cactus is grown or
imported for its variety of uses. Producers, owners, and workers will
become unemployed because they will not be able to harvest the plant in
the wild anymore. Many of these growers will have to bye replacement
foods that they might not be able to afford. Most of the workers have
been doing this their whole life and now will have to try to find
another job, with little experience in other fields, to support their
family. According to Simonson and Stohlgren "The cultivation of prickly
pear in Mexico involves 20,300 fruit producers and 8,095 producers of
nopalitos, generating 1.5% of total agricultural production and
represents 2.5% of the value of agricultural production" (Simonson, et
al., 2005). This crop makes it possible for some families to remain on
their land by growing these cactuses to make a steady income for
survival. Clearly, the decrease in production of the cactuses will lead
to severe economic loss and hunger.

In the United States and Mexico prickly-pear cactus are commonly used
for medicinal uses such as in lowering cholesterol, dietary supplement,
and in some cases used to treat diabetes. According to Altshul (2005)
"desert dwellers of North and Central America have used prickly pear to
treat skin diseases, burns, and joint and muscle pain." Different
cultures use these cactuses in different medicinal ways according to
their beliefs. In both the Mexican and American Society these cactuses
provide organic relief of many ailments and are commonly used by some
over pharmaceutical drugs. New research on the cactuses extract also
confirms when taken several hours before drinking alcohol, prickly pear
extract can prevent severe hangover symptoms, such as nausea, aversion
to food, and dry mouth (Altshul, 2005). With movement and contamination
of this moth these cactuses will not be able to be researched for their
full medical uses. It is clear that the cactus provides a wide range of
uses in foods, juices, liquors, medicinal and cosmetic purposes.

A more indirect effect on the economic severity of this moth is that it
is forecasted to move as far west as Texas where the cactuses serve as
fodder for cattle in times of drought and dry season. Since these
cactuses are among the only thing that can survive in these degraded
deserts it is important to maintain these cactuses because of their high
palatability, digestibility, and moisture content for animals. These
cactuses provide protein and food for cattle and other farm animals.
Without them more money will be spent to protect and feed them. The
reported value of prickly pear cactus to a small breeding herd of 50
cattle during the summer months when forage is limited could replace hay
forage valued at up to \$700 meaning the potential value in the 14
county Opuntia rich habitat of West Texas would be \$4 million during a
summer drought season (Simonson, et al., 2005). The majority of these
farmers do not have the money to spend on extra food for these cattle.
Unquestionably it's necessary to control the moth to protect the
landscape of these regions for not only economic safety but also for
environmental protection.

Without control and regulation of the cactus moth the environmental
impact will be very high disrupting ecosystems and biodiversity. Theses
plants posses the characteristics to maintain a stable ecosystem in the
dry arid regions in which they exist. Since deserts possess little
vegetation, the cactuses along with a few other plants prevent things
such as wind and rain erosion through their root systems. The Opuntia
species are probably the best plants for reforestation in these arid and
dry regions because of their high sustainability. Since it is a cactus
they don't need much water to survive and are able to grow in the
degraded soil of the deserts which make them special to desert habitats.
The loss of this cactus would directly affect other plants in the
ecosystem because the soil would not receive nutrients from the cactuses
which would affect the microbial world in the soil. Since microbes can
provide nutrients to other plants this will directly effect the little
other vegetation that is able to grow.

Wild life will also be affected with the loss of Opuntia in arid
regions. The moth will eventually lead to extensive destruction of
natural Opuntia populations that serve as food for wildlife such as
deer, javelin, rodents and coyotes (NISC, 2005). Not only do these
cactuses serve as food but Opuntia gives many animals shade and
protection from the hot summer sun and many species of birds nest in, or
otherwise rely on the opuntia species (Simonson, et al., 2005). In the
arid areas of the United States prickly pear cactus fruit are consumed
by a lot of herbivores because the fruits posses high water content.
Since water his harder to come by in these arid regions these cactuses
are extremely essential to many animals. Insects such as bees also use
the plant for its pollen and nectar in the flowers. Florida is at the
most risk because the cactus moth attacks all six native species and one
the them is the rarest Opuntia found (Simonson, et al., 2005). This will
lead to extinction if the moth is not controlled in specific areas
causing other animals to find other sources of food and protection.
Endangered species like the Texas tortoise will not be able to exist
without the cactus because they use them as protection and food
(Simonson, et al., 2005). It is critical to keep this plant intact
because of the huge environmental impact that would domino if this plant
were to be more endangered.

Consequently it is crucial to enact this proposed law as soon as
possible. It is critical to control the human dispersal of the cactus
moth through transportation even though there is an increasing trade in
the Opuntia species. The USDA and APHIS report that the expanding flow
of cacti material is far outpacing the inspection capabilities
(Zimmerman, 2004). Laws and early detection methods are needed to limit
the seriousness of the threat before it is too late. Because of the
cactus moths easiness of movement, high reproductive potential, and
dispersal ability, the cactus moth serves as a sever threat to Opuntia
species. Ultimately, the spread of the moth and its annihilation of
Opuntia species, if not controlled, will cause negative impacts on
social, economic, and environmental aspects of both Mexico and the
United States society.

Works Cited

Altshul, S. (Jan 2005). Head Off a Hangover: Prickly pear prevents
morning-after

> angst. *Prevention*, 57, 1. p.90. Retrieved March 17,
> 2008, from Student Resource Center - Bronze via Gale:
> http://find.galenet.com/ips/start.do?prodId=IPS

Bloem, Ken (2005, Jan. 3). *The Cactus Moth: Friend Turned Foe*. CPHST
News.

> Retrieved March 2, 2008 from cphst.aphis.usda.gov/newsletter
>
> /jan05newsletter.pdf

Durham, Sharon. (2006, September). *Sticking It to the South American
Cactus Moth*.

Agricultural Research, 1-10.

Habeck D.H., & Bennett F.D. (1998). *Cactoblastis cactorum Berg
(Lepidoptera:*

> *Pyralidae), a Phycitine New to Florida.* Florida Department of
> Agriculture and Consumer Services Division of Plant Industry. (333
> ed.) \[Circular\] Gainesville, FL.

Mississippi State University GeoResources Institute. (2007). *Cactus
Moth: An Invading*

*Pest*. \[Brochure\]. Mississippi.

Morgan, C. (Oct 9, 2002). Migration of moths presenting a prickly
situation. *Knight*

> *Ridder/Tribune News Service*, p.K0617. Retrieved March 15,
> 2008, from Student Resource Center - Bronze via Gale
> http://find.galenet.com/ips/start.do?prodId=IPS

NISC. (2005). *NISC Agencies Team Up to Control the Spread of Cactus
Moth.* Retrieved

> March 7, 2008, from
> http://www.aphis.usda.gov/plant_health/plant_pest_info\
> /cactoblastis/downloads/cactusmothstakeholder.pdf.

Simonson, S. E., Stohlgren, T. J., Tyler, L., Gregg, W., Muir, R., &
Garrett, L. (2005).

> *Preliminary assessment of the potential impacts and risks of the
> invasive cactus moth Cactoblastis cactorum Berg, in the U.S. and
> Mexico*. Austria: IAEA.

South American Cactus Moth; Quarantine and Regulations, 73 Fed. Reg.
7679 (2008) (to

be codified at 7 C.F.R. § 301)

Zimmerman H., & Bloem. S. (2004). *Biology, History, Threat,
Surveillance and Control*

*of the Cactus Moth, Cactoblastis cactorum.* Austria: IAEA*.*