Keep 'Em Outta Here!: An Introduction to Invasive Species

My room. My book. My house. Do any of these sound familiar to you? 

We all have things that we claim as our own, and when something or someone violates our sacred space, we get the feeling we have been violated or disrespected. We have been invaded.

This term - invasion - is a term that can also be applied to the natural world. Invasive species (of plants or animals) are prevalent throughout the world. According to the National Invasive Species Information Center (NISIC) an invasive species is: 

1. non-native (or alien) to the ecosystem under consideration, and
2. whose introduction causes or is likely to cause economic or environmental harm or harm to human health.

A wide variety of examples of invasive species can be found of in North America: 

• killer algae (Caulerpa taxifolia)
• black nightshade (Solanum dulcamara)
• Oriental fruit fly (Bactrocera dorsallis)
• European paper wasp (Polistes dominula) 

to name a few (click here to see a longer list of North American invasive species). According to a Washington Post article published in 2015, three out of the twelve "most destructive animals in the United States" are insects (emerald ash borer, brown marmorated stink bug, and the Asian citrus psyllid). 

[Follow this link if you are interested in reading the rest of the Washington Post article].

The emerald ash borer (Agrilus planipennis) was native to Russia, China, and Japan and was first identified in the United States in SE Michigan in 2002. Despite its tantalizingly attractive color, emerald ash borers have spread wildly and are continually desiccating ash trees in its wake.

Emeral Ash Borer https://static1.squarespace.com/static/53c0098ee4b06bdffe7d0f18/t/ 53f25c2ce4b01b6ee524fdc1/1408392262977/ The brown marmorated stink bug (Halyomorpha halys) first appeared in Allentown, PA in 1996 but has since spread to 42 other states in the U.S. It was introduced to American soil by cargo ships coming from China, where these bugs originate. In China, marmorated stink bugs are kept in check by a parasitic wasp that oviposits eggs into the adults and whose larvae, when hatched, then eat the stink bug for nutrients. These wasps, however, are not found in the mid-Atlantic regions, so the unchecked stink bugs flourished on American soil. Stink bugs cause problems for a variety of reasons - one obviously given away by their name: they stink. Not only do they give off bad odors (not to mention, they aren't that attractive) but they are devastating to fruit and vegetable crops, which in turn affects economic growth and values of produce for consumers.

Brown Marmorated Stink Bug

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/extra_large/public/_images/photogalleries/2013-01-11/

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In that same vein, the Asian citrus psyllid (Diaphorina citri) carries a bacteria that infects citrus trees (most notably, oranges and lemons). This pest was first noted in North America along the coast of Florida in 1998 but is now found all across the continent, into California, and even Hawaii. The bacterial disease that citrus psyllids carry is referred to by many different names, but most commonly known as Huanglongbing disease (HLB). This disease has been called by farmers as a citrus cancer because of the way that the tree dies after being infected, and the spread of this disease has infected more than half of Florida's citrus trees, and many more all across the U.S.

Asian Citrus Psyllid

http://www.cugarbio.com/wp-content/uploads/2016/09/images.jpg

These three insects are indeed very destructive to both the natural and economic arena in North America, and while there are an astronomical number of non-native invasive species in our backyards, have you ever thought about the destruction of invasive species that we are responsible for throughout the world?

Admittedly, when I hear talk of invasive species I tend to only think of those that are harming my environment - but what of the species that we have taken abroad? When I began searching for a list of destructive invasive species originating in the U.S. I was taken aback by what I found. 

One of the most notable, and extremely destructive, invasive insects that originated in North America is the Colorado potato beetle.

 

https://www.rodalesorganiclife.com/sites/rodalesorganiclife.com/files/articles/2015/07/potatobeetle-juergen-christine-sohns.jpg

This little beetle was originally thought to have been transported into Europe with potato exports coming from the U.S., and after hearing about this insect, European countries banned the importation of potatoes from North America (in 1875). A few years later, however, the Colorado potato beetle was still found in Europe. Over the next 30 years, it spread throughout the entire continent. While farmers struggled to keep this beetle off of their crops with chemicals, the potato beetle kept coming back more abundant than before. This was eventually contributed to the potato beetle's uncanny ability to develop chemical resistance, and is now resistant to "52 different compounds belonging to all major insecticide classes" (Alyokhin, 2008). The potato beetle also overwinters in diapause in the soil during winter months and has very high reproductive potential. The potato beetle's destruction of potatoes has widespread consequences, and it is so destructive because unlike most other insects, both the larvae and the adults feed on the same plants - the potato plants.

[To read more about the research done on the insecticide resistance follow this link]

The Colorado potato beetle is just one of many examples of North American invasive species that have caused widespread harm to their non-native environment - others include the American lobster, the rosy wolfsnail, and the American mink (for a few other examples click here). 

Sources:

Alyokhin, A., Baker, M., Mota-Sanchez, D. et al. Am. J. Pot Res (2008) 85: 395. doi:10.1007/s12230-008-9052-0

Brettingen, Paige. "Worst Presents Ever—8 Invasive Species the U.S. Gave the World." Takepart. Participant Media, 29 Jan. 2013. Web. 25 May 2017. <http://www.takepart.com/photos/most-invasive-species-us-has-exported/colorado-potato-beetle>.

Center, National Invasive Species Information. "About NISIC - What Is an Invasive Species?" National Invasive Species Information Center. USDA: United States Department of Agriculture, 24 May 2016. Web. 25 May 2017. <https://www.invasivespeciesinfo.gov/whatis.shtml>.

Fears, Darryl. "The Dirty Dozen: 12 of the Most Destructive Invasive Animals in the United States." The Washington Post. WP Company, 23 Feb. 2015. Web. 26 May 2017. <https://www.washingtonpost.com/news/energy-environment/wp/2015/02/23/like-most-invasive-species-pythons-are-in-the-u-s-to-stay/?utm_term=.3d0ff38f0aa9>.

MARSHALL, JORDAN M., et al. “Estimates of Agrilus Planipennis Infestation Rates and Potential Survival of Ash.” American Midland Naturalist, vol. 169, no. 1, 2013, pp. 179–193. JSTOR, www.jstor.org/stable/23525602

Mead, Frank. W, and Fasulo, T.R. "Featured Creatures: Asian citrus psyllid." University of Florida: Entemology and Nematology. FDACS/DPI Entemology Circular No. 180. Jun. 1998. Web. 26 May 2017. <http://entnemdept.ufl.edu/creatures/citrus/acpsyllid.htm>

Piiroinen, Saija, Leena Lindström, Anne Lyytinen, Johanna Mappes, Yolanda H. Chen, Victor Izzo, and Alessandro Grapputo. "Pre-invasion history and demography shape the genetic variation in the insecticide resistance-related acetylcholinesterase 2 gene in the invasive Colorado potato beetle." BMC Evolutionary Biology 13.1 (2013): 13. BioMed Central. Web. 25 May 2017. <https://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-13-13>.

Wikipedia Contributors. "List of Invasive Species in North America." Wikipedia. Wikipedia, The Free Encyclopedia, 08 May 2017. Web. 25 May 2017. <https://en.wikipedia.org/wiki/List_of_invasive_species_in_North_America>.