Taz and Ant; One Endangered, One Invasive

Taylor Drake

Biology 106A, Fall 2012

In a world dominated by humans there are many things that also inhabit Earth, one of those being animals. Sometimes these animals can thrive in certain or multiple geographical areas while others, due to humans, may fail to adapt and survive. An invasive species is one that has a native geographical range but then somehow gets transferred to a new geographical range where it possibly can thrive and cause problems such as the Red Imported Fire Ant. On the other hand, there are some species of animals that are endangered and on the brink of extinction like the Tasmanian devil. With the encroachment of humans on the animal’s environment, they have hindered their ability to thrive forcing them to become endangered. Humans influence on the ecosystem, animals have to adapt like the Red Fire Ant or be forced to near or possible extinction like the Tasmanian devil.
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The Tasmanian devil (Figure 1), Sarcophilus harrisii, is the largest carnivorous marsupial of the family Dasyuridae found on the Australian island of Tasmania (Figure 2) (Tasmanian devil). The devil is normally black with a white patch around its neck and generally about the size of a small dog weighing between fifteen and twenty Figure 1. The Tasmanian devil, Sarcophilus harrisii pounds (Tasmanian Devil). On Tasmania, it lives in coastal scrubs and eucalypt forests but is also found near places of human inhabitance because S. harrisii is a scavenger. Its days are spent sleeping in borrows of old wombat dens, constructed from hollow logs, or caves. Being nocturnal, the nights are when the devil is active. The Tasmanian devil primarily eats Figure 2. The current range of the Tasmanian devil, Sarcophilus harrisii. dead carcasses, also referred to as carrion, but will also attack living things generally smaller than themselves such as snakes, birds, lizards, rodents, and small lambs (Tasmanian Devil). The Tasmanian devil is known for having an extremely strong bite causing them to have the ability to eat the entire remnants of an animal.
Figure 3. Gondwana
The Tasmanian devil normally lives about six years and has the ability to reproduce after the second year. Mating season starts in March and continues through April. After about a month of pregnancy, around fifty or so offspring are born. The female devil only has four teats so that means that the first four offspring to attach themselves to the teat survive (Road 2012).
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Figure 4. The Original Range of the Tasmanian devil, Sarcophilus harrisii
There is a theory that ancient marsupials, similar to S. harrisii, migrated from what is now South America to Australia tens of millions of years ago during the time of Gondwana (Figure 3), and evolved as Australia became more arid (Tasmanian devil). Shown in Figure 4, the Tasmanian devil used to roam Australia’s entire mainland but due to competition with Dingoes and Aboriginals, it has not been seen there for over four hundred and sixty years (Sarcophilus harrisii).

According to the IUCN Red List, the Tasmanian devil is considered endangered due to the fact that in the last ten years, the global population of S. harrisii has decreased by sixty percent, which is mostly due to the fatal disease called Devil Facial Tumor Disease (Sarcophilus harrisii). Devil Facial Tumor Disease, or DFTD, “is an aggressive non-viral transmissible parasitic cancer,”(Devil facial tumor disease). It is spread when devils bite each other’s heads when fighting over food. First lesions and lumps form around the mouth but soon these develop into cancerous tumors and spread to the face and potentially the entire body (Figure 5). These tumors can interfere with feeding causing many of the devils to die from starvation (Devil facial tumor disease). Other threats to the Tasmanian devil are being road kill, hunted by humans, and the recent introduction of the Red Fox into Tasmania (Sarcophilus harrisii). From data collected in 2006 by Australia's Figure 5. Devil Facial Tumor Disease.
Department of Primary Industries, there are about twenty to fifty thousand mature devils left (Tasmanian devil - Frequently Asked Questions 2008).
There are things being done to help save the Tasmanian devil. First and foremost is there has been a major effort to breed insurance populations of Tasmanian devils that are free of the deadly disease. The next step in helping the Tasmanian devil is to learn more about DFTD. Scientists are trying to figure out how to stop the spread of DFTD and create a vaccine to help cure the two thirds of the current population that is infected with it.
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Figure 7. A Fire Ant’s mound.
Figure 6. The Red Imported Fire Ant, Solenopsis invicta
The Red Imported Fire Ant, Solenopsis invicta, is a small reddish brown ant (Figure 6). It is one of over two hundred and eighty different species of Solenopsis (Red Imported Fire Ant). The Red Fire Ant is an omnivore consuming mostly plant and animal material but its foods of choice is the insect (Red Imported Fire Ant). Around its food source is where the ant builds its home, which is a mound (Figure 7). Inside each mound there is around one hundred to five hundred thousand ants including a queen of the colony and worker ants. The queen has the ability to lie upwards of five thousand eggs a day (Red Imported Fire Ant (Solenopsis invicta)). Worker ants protect the queen and her eggs, build the mound, defend it, and locate and collect food. Solenopsis invicta can be a very aggressive animal. When provoked a Fire Ant will crawl up the arms and legs of the interloper and proceed to bite. Once it has bitten the victim the ant then will sting and inject necrotizing, alkaloid venom that causes a burning sensation and the skin to blister (Red Imported Fire Ant (Solenopsis invicta)).
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Figure 9. Current Range of the Fire Ant shown in red.
Figure 8. The original range of the Fire Ant in South America. Solenopsis invicta is originally from South America but around 1918, the Red Fire Ant was accidently transported from South America to the port of Mobile, Alabama via soil used on the ship as ballast (Figure 8) (Lockley 2009). Since being introduced in Alabama, it has spread throughout most of the southern states including Texas, Louisiana, and Mississippi where it has caused a lot of economical damage (Figure 9)(Lockley 2009). According to the FDA, roughly five billion dollars are spent each year combating medical treatment, damage caused, and control in infested areas In addition to that, seven hundred and fifty million dollars are spent each year in efforts to repair damage to agricultural assets, such as livestock and crop loss (Red Imported Fire Ant). Not only has the Red Fire Ant caused economic damage but also it has caused ecological problems. Research has been done with regards to the Red Fire Ant and the Eastern Bluebird and it was concluded that the Red Fire Ant altered both the reproductive success and strategies used by the bluebird (Ligon et al. 2011). The Red Fire Ant also has caused havoc to local ecological communities especially ground nesting animals. It has been known to completely eliminate species from the infiltrated environments and even has had an influence on insect’s ability to pollinate flowers (Lockley 2009). To stop the damage and spread of the Red Fire Ant, there are many things being done. One problem though that is of concern is that S. invicta does not have a natural biological control agent so the bulk of research is centered around introducing one of these from the Red Fire Ant’s native range (Red Imported Fire Ant). The main method that has been successful in exterminating the ant has been to destroy the mound. This method consist of pouring boiling water into the mound, injecting liquid nitrogen into the mound, and even pouring gasoline on the mound and lighting it on fire (Red Imported Fire Ant). The problem with this method is that even though the entire nest and almost all worker ants are burned instantaneously, the queen lives several feet below the surface so the flame sometimes does not reach her. Another method for killing an ant colony has to do with food baiting. Worker ants take a pesticide, corn grit covered in soybean oil for example, back to the colony where it is shared with the queen. The pesticide then will make the queen infertile or lead to her death (Texas Imported Fire Ant Research and Management Project).
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The Red Imported Fire Ant is a successful invasive species because it has a high reproductive capacity, large colony size, and wide food range. The Tasmanian devil has become endangered due to an unlucky disease, a new predator, and human causes such as hunting and accidents. The future and fate of the Tasmanian devil, if serious progress is not made to help prevent the spread of DFTD, is very bleak. As suggested in the Austrian Geographic, if a solution is not found soon then the wild population of Tasmanian devil could be gone within the next twenty five years (Hanson 2012). The disease will continue to spread and kill the entire population left in the wild, but on the other hand, many insurance populations are being made that are free of DFTD, so when DFTD is figured out they can introduce these insurance populations into the wild and begin the recovery process. The Red Fire Ant is not done spreading yet. There is research that has discovered that the Red Fire Ant from southern America, not the original species from South America, has spread to other parts of the world. So far there is still no major method that will terminate large quantities of these ants. Therefore as the Fire Ant evolves, it may gain the ability to survive in cold climates and if this happens then there is no reason why it will not continue to spread and eventually be found around the whole United State and possibly the World.

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References Cited
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Devil facial tumour disease. Available: http://en.wikipedia.org/wiki/Devil_facial_tumour_disease. Last accessed 29th Oct 2012.

Hanson, Jenna. (2012). Tasmanian devil genome offers cancer clues. Available: http://www.australiangeographic.com.au/journal/tasmanian-devil-genome-offers-cancer-clues.htm. Last accessed 29th Oct 2012.

Ligon, R. Siefferman,L. and Hill, G. (2011). Invasive Fire Ants Reduce Reproductive Success and Alter the Reproductive Strategies of a Native Vertebrate Insectivore. Available: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0022578. Last accessed 29th Oct 2012.

Lockley, T. (2009). Imported Fire Ants. Available: http://ipmworld.umn.edu/chapters/lockley.htm. Last accessed 29th Oct 2012.

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Red Imported Fire Ant (Solenopsis invicta). Available: http://www.desertmuseum.org/invaders/invaders_fireant.php. Last accessed 29th Oct 2012.

Road, J. (2012). Tasmanian devil. Available: http://www.koala.net/devil.html. Last accessed 29th Oct 2012.

Sarcophilus harrisii. Available: http://www.iucnredlist.org/details/40540/0. Last accessed 29th Oct 2012.

Tasmanian Devil. Available: http://australian-animals.net/devil.htm. Last accessed 29th Oct 2012.

Tasmanian devil. Available: http://en.wikipedia.org/wiki/Tasmanian_devil. Last accessed 29th Oct 2012.

Texas Imported Fire Ant Research and Management Project. Available: http://fireant.tamu.edu/. Last accessed 29th Oct 2012.
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